This PDF file contains the front matter associated with SPIE Proceedings Volume 12157, including the Title Page, Copyright information, and Table of Contents.

The processes involved in picosecond infrared pulsed laser annealing of multylayer structures consisting of alternating thin films of amorphous silicon and germanium were investigated. The films were fabricated by plasma-chemical deposition on Si(001) and glass substrates. An analysis of structural transformation of Ge/Si multi-nanolayers was performed using Raman spectroscopy. Regimes of annealing were found when the Ge layers are partially crystallized while the Si layers remain amorphous without noticeable intermixing of Ge and Si. The developed approach can be used for creation of GeSi solid alloys (which can be used in memristors on not refractive substrates) and also for creation of Si based p-i-n structures on non-refractory substrates with Ge nanoclusters in i-layer, that can enhance the efficiency of thin film solar cells.

The results of a study of the real structure, electrical and photovoltaic characteristics of a monolithic solar module of 15 cells, made based on an array of p-n junctions in a Si (111) silicon wafer, are presented. The p-n junctions were formed by the boundaries of through vertical Al-doped (C= (0.95-1.05)×10¹⁹ cm^-3) Si channels 100 μm wide at a distance of 3 mm. The perfection of the crystal lattice in the channel and near its boundaries has been investigated by X-ray methods: projection topography and high-resolution diffractometry in the transmission and reflection geometry. It is shown that the channel-matrix interface is coherent and there are no misfit dislocations on it. Typical defects in the p-channel are dislocation half-loops, which are located parallel to the surface of the wafer in its near-surface layer. The investigated solar 15-cells module demonstrates an efficiency of 13% at output 7.5 V and 30 mA. These photovoltaic parameters are comparable with the main electrical parameters of the planar analogues, despite the design features of the Si(Al) channels and the presence of structural distortions near the boundaries of the substrate matrix.

This article discusses the prospects for the use of composite materials for the equipment of space systems for remote sensing of the Earth. One of the development problems in the design of special-purpose equipment is disclosed. This problem is observed when using traditional materials in the design of special-purpose equipment. Its solution is the use of new composite materials that can provide the required characteristics with a margin of safety ^[1]. The most widely considered composite material is "SKELETON". Its strength and thermal characteristics were given ^[4]. On the example of an optoelectronic converter, a simulation of tests using this material was carried out. Based on the results of 3D modeling of strength tests and heat sink, a conclusion was made about the possible use of this material. Other composite materials were also given as an alternative.

The development of A^IIIB^V photodetectors with subpicosecond response time seems to be one of core problems in modern optoelectronics. Its solution is required, in particular, for the implementation of high-speed and high-level optical interconnections in ultra-large-scale integrated circuits. Previously, we proposed the concept of a photodetector with controlled relocation of carrier density peaks whose structure allows for mobility and lifetime modulation and, as a result, reduction of back-edge photocurrent lag in photosensitive p-i-n heterojunction. In this paper, we perform the analysis of electron and hole transport in the aforementioned sensor using a time-domain drift-diffusion semiclassical model. Numerical solution of the system that contains the two-dimensional continuity and Poisson equations allows us to evaluate key characteristics of the photodetector with controlled relocation and to modify its structure and photoreceiver circuit reasonably.

The transmission and reflection spectra of arrays of heterogeneous nanowires made of Ni/Co, FeNi/Co, and Ni/Fe, formed in track polymer membranes by the galvanic method, have been studied in the frequency range from 16 to 250 THz. Many peaks in the 16-20 THz range were found in the transmission spectra, while they are not observed in the spectrum of a track membrane without nanowires. The absorption spectra of an array of nanowires in a track membrane and a membrane without wires are calculated from the obtained spectra. It was found that the fraction of the THz radiation power absorbed by nanowires and its spectrum depend on the materials of the nanowires. The features of the observed spectra can be explained by two mechanisms. The first is the inverse laser effect in magnetic nanocontacts. And the second is the change in electrical resistance due to spin-flip transitions between the spin subbands in the case of a non-coplanar distribution of the magnetization of the magnetic layers. This class of quasi-one-dimensional structures looks promising for creating THz radiation detectors in a wide spectral range and at room temperature.

The study of GaAs/AlAs terahertz resonant tunneling diodes demonstrates the competition of self-excitation and amplification processes incorporating the terahertz-range polaritons. The effects of the magnitude of the resonant peak current and low current in the valley of the current-voltage characteristic are demonstrated taking into account the general laws of detection in the mode of internal amplification in the region of negative differential conductivity.

Emerging spin transfer torque magnetoresistive random access memories (STT MRAM) are nonvolatile and offer high speed and endurance. They are promising for stand-alone and embedded applications in the automotive industry, microcontrollers, Internet of Things, frame buffer memory, and slow SRAM. The MRAM cell usually includes a CoFeB fixed reference layer and a free magnetic layer (FL), separated by a tunnel barrier. To design ultra-scaled MRAM cells it is necessary to accurately model the torques acting on the magnetization in composite magnetic layers with one or several nonmagnetic inclusions between the ferromagnetic parts. The magnetization dynamics is governed by the Landau-Lifshitz- Gilbert (LLG) equation supplemented with the corresponding torques. The torques depend on nonequilibrium spin accumulation generated by an electric current. The electric current and the spin accumulation also depend on the magnetization. Therefore, the LLG and the spin-charge transport equations are coupled and must be solved simultaneously.

We apply the finite element method (FEM) to numerically solve this coupled system of partial differential equations. To develop an open source solver, we use well-developed C++ FEM libraries. The computationally most expensive part is the demagnetizing field calculation. It is performed by a hybrid finite element-boundary element method. This confines the simulation domain for the field evaluation to the ferromagnets only. Advanced compression algorithms for large, dense matrices are used to optimize the performance of the demagnetizing field calculation in complex structures. To evaluate the torques acting on the magnetization, a coupled spin and charge transport approach is implemented. For the computation of the torques acting in a magnetic tunnel junction (MTJ), a magnetization-dependent resistivity of the tunnel barrier is introduced. A fully three-dimensional solution of the equations is performed to accurately model the torques acting on the magnetization. The use of a unique set of equations for the whole memory cell including the FL, fixed layer, contacts, and nonmagnetic spacers is one of the advantages of our approach. To incorporate the temperature increase due to the electric current, we solve the heat transport equation coupled to the electron, spin, and magnetization dynamics, and we demonstrate that the FL temperature is highly inhomogeneous due to a non-uniform magnetization of the FL during switching.

Spin-orbit torque (SOT) MRAM is fast-switching and thus well suitable for caches. By means of micromagnetic simulations, we demonstrate the purely electrical switching of a perpendicular FL by the SOTs due to two orthogonal short current pulses. To further optimize the pulse sequence, a machine learning approach based on reinforcement learning is employed. Importantly, a neural network trained on a fixed material parameter set achieves switching for a wide range of material parameter variations.

The modeling of conventional (deterministic) electronic circuits – ones consisting of transistors, resistors, capacitors, inductors, and other traditional electronic components – is a well established subject. The cycle-to-cycle variability of emerging electronic devices, in particular, certain ReRAM cells, has lead to the concept of stochastic circuits. Unfortunately, even in relatively simple cases, the direct transient analysis of stochastic circuits is computationally demanding and potentially impractical, if possible at all. An important development in this area has been the application of a master equation that is easily implemented in SPICE. In this conference paper, we briefly review the master equation approach and present an improved implementation of this approach in SPICE. Moreover, we find an attractor state in a periodically driven memristive circuit – a stochastic counterpart of deterministic memristor attractors.

For the development of information technology, more and more memory arrays are needed. Recently, memristors have been the most promising candidates for the creation of modern universal memory. The possibility of light stimulated resistive switching (RS) is promising for creating optical computers, technical vision and neuron networks. The studied Si_xGe_yO_z solid alloys films (~50-65 nm) were obtained by simultaneous evaporation of GeO₂ and SiO₂ (or SiO) powders in high vacuum (10^-8 Torr) and deposition onto n+-type, p+-type Si(001), and on Al/SiO₂/Si(001) heated up to 100°C. The transparent indium tin oxide (ITO) contacts were used as top electrode. It was found, that as-deposited GeO_x[SiO]_(1-x) films contain amorphous Ge (a-Ge) nanoclusters. The furnace annealing at temperature 500 °C lead to further forming of a-Ge clusters in both types of the films. Reversible (up to several thousand cycles) RS from high resistance state (HRS) to low resistance state (LRS) (memristor effect) were observed for the semiconductor-dielectric-metal structures, namely p+-Si (or n+-Si)/ GeO[SiO₂] (or GeO[SiO]) /ITO structures (MIS structures) in air atmosphere. Both negative and positive photoconductivity was observed in the annealed MIS structure when both negative/positive voltage biases were applied to the top ITO electrode. This is possibly due to light-stimulated recharging of holes from a-Ge nanoclusters, which act as deep traps. The effects of light-induced RS was observed for annealed MIS structures based on GeO[SiO] films with a-Ge nanoclusters. These results are promising for creation of photomemristors and optoelectronic devices combining the properties of a memristor.

Neuromorphic computing has been raised as an excellent alternative to conventional digital computing due to scaling limits and heat removal difficulties. At the same time, neuromorphic computing makes special memory requirements, such as high-speed, durability, compatibility with CMOS technology. ReRAM meets these requirements perfectly. Therefore, the goal of this work is to better understand the physics of growth and rupture of metal-like filament in ReRAM.

In this work we have studied functioning of memristors based on TiN-TiO₂-SiO₂-W open edge sandwich structures on Si substrates in inert gas medium. A custom-made experimental setup that allowed controlled gas atmosphere within the pressure range of 0.0001-750 Torr was used. The electroforming was performed by a procedure of applying a quasistatic electric pulse of 10-20 V. The resistive switching was performed by pulses of 5 V, 30 ms for the “ON” switching and 5-8 V, 100 ns for the “OFF” switching. We carried out investigations for nitrogen and argon inert gases. As a result, first, we have established that the resistive switching in inert gases (both nitrogen and argon) of the memory elements electroformed in vacuum, reliably takes place in the entire inert gas pressure range including the maximum experimental value of 1 atm. Second, we showed that the electroforming takes place at the maximum inert gas pressure of 100 Torr.

The study of electroforming processes in various open sandwich metal-SiO₂-metal structures (with different materials of electrodes) and I–V-curves at both voltage polarities allowed to find the main factor responsible for the presence of stable electroforming and the absence of breakdowns after electroforming (N-shape I-V-curve can be drawn repeatedly). This factor is making of structure anode of tungsten at any (top or bottom) position of this electrode. The use of molybdenum instead of tungsten in such structures essentially allows to decrease the electroforming voltage (from 10-11 to 4-5 V), which makes the process more reliable.

In this study we investigated the influence of kind of metal on memristor effect in metal-insulator-semiconductor (MIS) structure. First, different metals have different work functions. This parameter can affect the flow of current through the MIS structure. Secondly, different metals have different binding energies of atoms. In this case, the bond energy consists of the energy of the metallic bond and the energy of the covalent bond. If we consider the model of the conductivity switching effect, in which a metal filament appears, this can affect the probability of its appearance. Thirdly, different metals and different methods of their deposition have different technological compatibility and ease of use. Two types of dielectrics were used for the experiments - silicon oxide and silicon nitride. Thin dielectric films were deposited on ptype monocrystalline silicon wafers. It was found that the best results among the tested metals were obtained using nickel deposited by electron beam evaporation. Copper proved to be poorly compatible with silicon oxide, since it easily diffuses into it and silicon. The other metals demonstrated the possibility of the appearance of the memristor effect. However, the yield was generally less than when nickel was used.

In this work it is established that for regularities of the magneto-optical response from curved magnetic nanosructures, a crossover occurs at certain scales. At scales less than characteristic length the normalized value of magneto-optical hysteresis loop for transverse magneto-optical Kerr effect does not depend on incident angle of electromagnetic radiation. For curved nanostructures at scales of the order or large than characteristic length and at certain incident angles, hysteresis loops were observed that are inherent in magnetic vortex structures. For systems based on nanometers thick cobalt films deposited on various nanostructured substrates the characteristic length is of about of 100 nm. On the basis of the experimental data the energy consumption for the formation of vortex structures is estimated.

This paper describes the design of the developed sensing element (SE) of a micromechanical accelerometer (MMA). Devices using SE data are used to measure acceleration (apparent). SE MMA is manufactured using a technology based on operations that make up the technology of semiconductors, mainly silicon, devices, and integrated circuits. But it has a number of significant features and problems that have to be taken into account when using typical technological processes for specific micromechanical structures and systems.

The paper considers the process of anisotropic etching of silicon, which makes it possible to form a three-dimensional SE structure. A numerical estimate of the errors arising during the formation of protrusions that form the gap is given. And even the influence of these errors on the output parameters of the MMA.

Reducing the complexity of the architecture of radio-frequency systems and subsystems of 5G mobile networks and Internet of Things currently requires the presence of passive RF components with very high performance. Considering these requirements, the technology of radio-frequency microelectromechanical systems for the development of passive RF devices allows us to solve the corresponding tasks related to the requirements of 5G and Internet of Things, concerning passive components and building blocks. Packaging of radio-frequency microelectromechanical systems and other passive components is a delicate issue, especially in line with future application contexts such as 5G and the Internet of Things, in which operating frequencies are approaching millimeter waves. In fact, when working with radio-frequency signals, the package, in addition to protecting encapsulated devices, should also have as limited an impact on their electromagnetic characteristics and performance as possible. Therefore, the packaging design stage must be carried out with extreme care. In this study, the verification of the methodology for electromagnetic modeling of a packaging solution at the wafer-level using through silicon vias for redistributing an electrical signal from passive radio-frequency microelectromechanical devices in package to other radio-frequency devices is discussed using the example of the developed capacitive radio-frequency microelectromechanical switch with double-clamp.

Microelectromechanical systems (MEMS) switches are attractive for radio frequency and microwave systems due to outstanding performance, but low reliability limits application of these devices. To date, a number of reliability problems are overcome, but some of them get little attention. This work describes the first experimental results on a novel failure mechanism of the MEMS switch with electrostatic actuation. The device is fabricated on a thermally oxidized silicon wafer with chromium adhesive layer. After several thousand working cycles, nanostructures containing adhesive material emerge at the gate. They coalesce into micron-sized defects that touch the beam during actuation and disturb normal operation. The material transfer also takes place at the substrate around the gate. This phenomenon was not reported in the literature, although Cr is widely used for microfabrication. The reasons for material transfer must be revealed in order to exclude this failure mechanism for MEMS devices.

Microfluidic systems such as labs-on-a-chip or drug delivery devices require a built-in actuator to drive pumps and valves. The electrochemical actuator is a promising option due to its compact size, low power consumption and high integration capability, but long time of gas termination makes this device rather slow. Recently, the actuator of a new type was demonstrated, which is based on the electrolysis of water performed by microsecond voltage pulses of alternating polarity (AP). It operates several orders of magnitude faster than the conventional DC actuator, but extreme operation conditions lead to the electrode degradation and rapid decrease of the performance. In this work, we demonstrate the long-term operation of the actuator without significant loss of the stroke. This result is achieved due to a new working regime, in which the time interval between series of AP pulses is filled with single polarity (SP) pulses, in contrast with the normal regime, where the SP pulses are not used. The new regime is realized by a specially developed pulse generator that tracks the current flowing through the electrodes and adjusts the amplitude of SP pulses to stabilize the current at a given level. We verify the current stabilization regime at the actuator with the oxidized Ti electrodes and compare it to the normal operation.

In this paper, we consider a method for constructing MEMS structures using a self-assembly operation based on controlled self-organization of mechanically stressed semiconductor layers. This work describes the design of highly sensitive tunneling linear acceleration sensors, as well as a nanoelectromechanical switch with two tunnel contacts. Accelerometers of this type have important advantages: hypersensitivity due to the tunnel effect, small dimensions compared to capacitive accelerometers, design flexibility due to wide construction variations depending on requirements, potential possibility of manufacturing structures with three axes of sensitivity in a single technological production cycle, high manufacturability. Tunneling nanoelectromechanical switches also have several advantages: such as low leakage current, energy efficiency, stability, good dynamic characteristics, and can be used in ultra-low-power electronics.

This paper presents the results of gas-phase deposition of silicon epitaxial layers studies obtained under real production conditions. The research is based on innovative techniques that have expanded the physical understanding of the process, which has improved the adequacy of the final results. Based on the developed physical modeling methodology, a study of the silicon epitaxial layers deposition process was carried out. The results were processed in a generalized form and could be represented by simple criterion relations. Based on the studies the area of the technological process with maximum possible homogeneity of silicon epitaxial layers deposition parameters was determined. It was shown that the silicon epitaxial layers deposition rate is determined by the interaction between the outgoing flow (from the nozzle) and reverse flow (at the moment when the wafer is between the nozzles). The use of the technique based on the autodopping effect showed that the distribution of the dopant impurity (from the local source) in the deposition zone is inhomogeneous and a significant part of the impurity is transferred in the direction of the jet flow. The plasma chemical deposition process of SiH_xN_y has been studied. As a defining parameter of the plasma chemical deposition process, the number Re_L characterizing the gas dynamics of the process is chosen. Studies were performed at pressures in the reaction chamber of 100, 50, and 10 Pa, which corresponds to values Re_L =1.2, 0.8, and 0.4. It is shown that greater uniformity of the deposited layer occurs at higher pressures.

In this paper, a systematic method for designing a basic thermal MEMS design is discussed using the example of a thermal micromechanical mirror developed by MIET. The mirror is made with microelectronic technology and consists of two movable bimorph structures made of aluminum and silicon dioxide. A reflective element with an aluminumcoated surface is attached to the movable beams. The movable beams are fixed to a silicon substrate and are controlled by applying а voltage to electrical heating elements formed inside the movable beams. Heating causes uneven expansion of the materials that make up the beams, which in turn causes the structure to move. The proposed design process involves algorithmic design using three developed models to determine the initial parameters of the thermal actuator, its static and dynamic characteristics, and the response to the control action. The use of such an algorithm in the design flow allows for a quick selection of the basic geometric and physical parameters that should ensure that the actuator has the required performance and characteristics. This significantly reduces the time taken during the initial design phase of the device.

A device for harvesting the energy of mechanical vibrations and converting it to electricity by the piezoelectric effect is simulated. The main part of the harvester is a multilayer cantilever with a piezoelectric layer sandwiched between two metallic electrodes. The cantilever typically has a rectangular design, which is characterized by insignificant deformation of the free end. As a result, this region undergoes low mechanical stress and produces small amount of electric charge. A tapered shape of the cantilever increases the stress at the tip and, therefore, enhances the performance. In this work, we investigate the stress distribution and output characteristics of the energy harvester with the tapered cantilever. Reducing the width of the free end increases the stress in this area for 4.5 times compared to the conventional design, which raises the average stress by more than 60%. The tapered design increases the output power and voltage by more than 20%.

In this work, we consider the formation of a sensor layer 100 nm thick based on platinum-doped tin oxide. We investigated the method of forming an oxide film using magnetron sputtering Sn and Pt in Ar+O₂ plasma. Using X-ray diffraction, it was found that the film consists of nanoscale particles with a metal core. The average size of the nanoparticles forming the film was from 47 to 74 nm The characteristics of the film were measured during additional oxidation in the temperature range from 300 to 700 °C. Thanks to annealing, the resistance of the sensor layer can be varied from 10 kΩ to 100 MΩ at a detection temperature of 300 °C The optimized film has been tested to detect ethanol, acetone, and ammonia at streams of 50, 100, 150 ppm.

One of the ways to create highly sensitive gas sensors based on graphene is to modify graphene by forming nanometer-sized channels in it. In this work, ion beam etching was used for these purposes. The necessary doses of Ga⁺ focused ion beam (FIB) were found to etch graphene. Several different structures based on modified graphene have been manufactured and investigated. A method for manufacturing graphene structures with a width of less than 10 nm by Ga⁺ FIB has been found. Also, high conductivity for structures of nanogap with polyaniline (PANi) was found, which can be used as selective gas sensing structures. The paper presents the responses of structures with nano-channel of PANi between modified graphene electrodes to different concentrations of ammonia and water.

Two-dimensional transition metal dichalcogenides (TMDC) and MoS₂ in particular are promising materials as sensitive layers for gas sensing due to room operation temperature, high sensitivity, low dimensions, vast methods of selectivity alteration, etc. MoS₂ response to toxic gases exposure depends on applied electric field that expands capabilities of resistive detection techniques, therefore, requires in-depth study. We fabricated a back-gated MoS₂ based field-effect transistor (MoS₂-FET) with standard photolithography technique on Si/SiO₂ substrate. AFM microscopy confirmed the single layer nature of MoS₂ flakes by cross-section featuring a thickness of 0.7 nm. Raman spectroscopy revealed A_1g and E¹ _2g modes position at 403.5 cm^-1 and 382 cm^-1 respectively. The mobility in the absence of passivation was about 10^-1 cm² V⁻¹s⁻¹. MoS₂-FET exhibits room-temperature NH₃ sensing with resistive response to 200 ppm exposure of about ~60%, signal-to-noise ratio about 8, and response/recovery time about 100 s.

The article presents the results of designing, manufacturing, and studying the resonant properties of a square silicon membrane for use in a fiber-optic acoustic receiver. The dependences of resonant frequency on edge length (6-9 mm) and thickness of the membrane (30-50 μm) are obtained. The geometrical parameters of the membrane satisfying the values of resonant frequency (2-60 kHz), pressure (0.1-14 Pa), and deviation (10 nm) are determined: edge length is 8 mm and thickness is 40-50 μm (9.2-42.3 kHz). A series of square silicon membranes was fabricated by anisotropic wet etching. The amplitude-frequency characteristics of the membranes were experimentally measured using an adaptive holographic interferometer. For a square membrane of 8×8×0.044 m³, the experimentally measured resonant frequency was 10.1 kHz, which is consistent with the results of numerical simulation.

Substantial progress in superconductor analog to digital converters (ADCs) and digital circuitry makes possible development and implementing broadband receiving systems with direct signal digitizing and by single ADC and following digital extraction of sub-bands with programmable band location and bandwidth. To provide the overall system performance as high as the superconductor ADC allows, one has to develop and implement a completely superconductive receiving antenna unit with using active superconductor antenna The antenna characteristic and design issues are considered and discussed in the paper.

The paper presents the design features of silicon microprobe with a cross-sectional size less than 100 μm, taking into account the number of electrodes, as well as the conditions of anisotropic wet etching. Analytical calculations were carried out for the probe structure, represented by n-regions of various widths, carrying up to 2n-1 electrodes. The dependences of bottom width of the trapezoidal section of the probe and width of related mask on the thickness and top width of the probe are obtained. The permissible dimension ranges for several cases of one- to four-level microprobes have been established. The correction value of the mask size was estimated, reflecting the effect of etching conditions on the geometry of the probe. Modeling was carried out in an anisotropic wet etching simulator taking into account the conditions of KOH etching (in 20-40% solution at 60-80°C). It allowed to refine the results of the analytical calculations, refine dimensions of the silicon microprobe structure, the geometry of related masks, as well as the extent undercutting effect. The obtained results could be used in development of silicon microprobes formed by anisotropic wet etching.

The development of field-effect transistors (FETs), resonant-tunneling diodes (RTDs), vertical heterostructures and other device structures on the basis of 2D materials is one of the important tasks for producing a new element base for micro and nanoelectronics.

The wave function formalism was applied in the development of numerical model of vertical heterostructures based on 2D materials [1, 2]. Combined self-consistent models [3, 4] were adapted for the case of taking into account vertical transport in the conduction band. The influence of various factors on the electric characteristics of the vertical heterostructures based on graphene, h-BN and MoS₂ was investigated with the use of the developed model. The IVcharacteristics of such structures were calculated for different number of layers of 2D materials that forms potential barriers and quantum wells. Comparison of the results of simulation of the investigated structures is carried out.

A numerical combined model based on a self-consistent numerical solution of the Schrödinger and Poisson equations in the active region of the device was used to calculate the IV-characteristics of GaN/AlGaN-based RTDs with vertical transport [5, 6]. The proposed model was used to study the effect of the aluminum concentration in the barriers on the IV-characteristics of the considered RTDs.

Developed quantum drift-diffusion model of FET based on monolayer graphene was described in detail [7, 8]. The model is based on quantum drift-diffusion approximation of carrier transport. Graphene channel is located between topand back-gate dielectrics. With the use of the model simulation of dual-gate FET with channel width 18 μm was considered. A good agreement with experimental data was obtained for number of applied voltages. Adequacy of the model is confirmed by these calculations.

The programs realizing the proposed models were included in the nanoelectronic devices simulation system developed at the BSUIR since 1995 [9, 10].

We use a linear approximation for the threshold voltage dependence on the body bias to derive the equation for the equivalent output resistance of the “extrinsic” MOSFET in the saturation regime. Previously we derived an equation for the equivalent output resistance of the “extrinsic” MOSFET in the saturation regime, that is based on the “intrinsic” transistor finite output resistance in the saturation regime. But we did not account for the body effect, i.e., the threshold voltage dependence on the body bias applied between the source and the fourth (body) MOSFET terminal. For the earlier generations of MOSFETs, the theory predicts that threshold voltage is a sublinear function of the body bias. However, modern transistors with steep retrograde body doping profiles exhibit an approximately linear relationship between a threshold voltage and a body bias, which allowed us to include the body effect into the compact model of an “extrinsic MOSFET. In addition, we discuss the application of our results to the theory of a common-source amplifier with an NMOS transistor with source degeneration.

A theoretical model of the high-frequency electrical conductivity of a semiconductor nanolayer is constructed within the framework of the quantum theory of transport phenomena. The layer thickness can be comparable to and less than the de Broglie wavelength of charge carriers. The isoenergy surface has the shape of an ellipsoid of revolution, the main axis of which is parallel to the layer plane. Analytical expressions are derived for the conductivity tensor components as a function of dimensionless thickness, electric field frequency, chemical potential, ellipticity parameter, and surface roughness parameters. The dependences of the longitudinal and transverse conductivity tensor components on the above parameters are analyzed. The results are compared for the cases of a degenerate and non-degenerate electron gas. A comparative analysis of theoretical calculations with known experimental data for a silicon film is performed.

At present, a great deal of interest is observed in devices based on two-dimentional (2D) materials, especially graphene, in the field of micro- and nanoelectronics. Graphene has robust hoheycomb lattice structure and unique properties such as ambipolarity, high carrier mobility, high conductivity. Nevertheless the properties of mono- and bilayer graphene are different. A significant difference in electrical characteristics of field-effect transistors (FETs) based on mono- and bilayer graphene was shown in few experimental works [1-3]. Note, that FET on bilayer graphene has demonstrated improved characteristics in comparison to FET on monolayer graphene [1,4,5]. Therefore a necessity to create models specifically for FETs on bilayer graphene appears. A tunable band gap is observed in the FET, when a perpendicular electrical field is applied to the bilayer graphene channel [6]. In the paper a quantum drift-diffusion model of FETs based on bilayer graphene is proposed. The model is a combination of electrical and physical models [7]. The mechanism of carrier transport along the bilayer graphene channel is considered. The electrostatic potential of the transistor channel is defined according to the band gap. Simulation of graphene dual-gate FET with channel length 4 µm is performed using the proposed model. Calculation of electrostatic potential of the investigated device structure was carried out. A good agreement with experimental data has been obtained for output characteristics of FETs based on monolayer graphene [8] using the developed model for this case. Different design parameters of FETs such as channel length, channel width, thickness of top- and back-gate dielectrics are used in the models. The proposed models of different FETs were included in the nanoelectronic devices simulation system NANODEV [9] developed at the BSUIR since 1995.

Drain current photoresponse of deep submicron SOI MOSFET with 50 nm channel length is simulated by ensemble Monte Carlo method. The photoresponse is simulated under the effect of picosecond laser pulses with 532 and 650 nm wavelengths at 5⋅10¹⁰ and 10¹¹ W/m² intensity. The current decay and the dynamics of generated charge carriers in the transistor channel are studied.

We demonstrate in this paper some applications of a general approach for constructing field-effect transistor compact models based on decomposing of FET modeling into two independent parts: device electrostatics and continuity equation. While the latter part has a universal form for any field-effect devices, the electrostatics is specific for different types of transistors which is expressed in different dependencies of the channel charge density upon gate voltage. We discuss here two applications of this approach using the examples of Schottky barrier MESFETs and organic field-effect transistors.

The dosimeters based on RADFETs are high actual for utilizing in space where the low dose rates irradiation prevails. The paper presents new experimental data on low-intensity irradiation of p-MNOS based RADFET. The obtained results were compared with the results of irradiation at high dose rates. The effect of ELDRS and the simultaneous annealing effect on different types of samples were discussed. The sensitivity of both types changed similarly at the range 1-100 rad(Si)/s. However, for dose rates less than 1 rad(Si)/s, the effect of the simultaneous annealing on change in the threshold voltage shift in time was clearly noticed only for samples with 500 nm oxide and absented for samples with 150 nm oxide.

The paper discusses methods for increasing the resistance of silicon semiconductor devices to ionizing radiation. A key feature of the presented methods is that there is no need to modify the topology, i.e. the described technological methods make it possible to increase the stability of integrated circuits by adding some technological operations to the standard process flow (not radiation hardy).

This paper shows the result of working out the operations of temporary bonding of Si-Si wafers and Si-glass wafers. The influence of materials and parameters of technological operations on the warpage of the resulting structures was investigated in order to reduce the bending of the device wafer when performing the processes of temporary bonding and thinning.

Cryogenic etching of silicon in SF₆/O₂ plasma is the process of choice for fabrication of deep high aspect ratio structures with strict requirements for sidewall angle, surface roughness and contamination, including MEMS, X-ray optics, and supercapacitors. The manufacturing of such structures, containing features of various size and shape, poses new challenges for the etching process optimization, since the key parameters of the resulting structures depend on the local aspect ratio and the shape of the mask aperture. As an aid in process optimization, we propose a three-dimensional Monte-Carlo simulator for the cryogenic etching of complex structures. It employs a surface kinetics model tuned to SF₆/O₂ process in 2 1⁄2D geometry and cubic voxel representations of simulation domain. Systematic study on cryogenic etching of test structures of different mask shape and aspect ratio is performed and principal mechanisms affecting etching results are identified.

In recent years, aluminum oxide films have found application in surface acoustic wave sensors. The paper presents the mechanical and physical properties of aluminum oxide (Al₂O₃) films obtained by the sol-gel method and subsequent sintering by high-temperature annealing. The synthesis of an aluminum oxide film from inorganic sols using the sol-gel technology was carried out. The effect of high-temperature treatment on the geometric dimensions, surface morphology, and hardness of Al₂O₃ films has been investigated. It was found that due to high-temperature sintering, the average values of film thickness and surface roughness are reduced by about 2 times. The effect of sintering temperatures on hardness suggests that with increasing temperature hardness of aluminum oxide film increases, and at sintering temperature of 800°C was 11.7±1.2 GPa.

The work studies the induced bistability phenomenon in a thermal reactor elements involved in radiation heat exchange with the silicon wafer exhibiting bistable behavior. The heat balance equations for a silicon wafer and elements of a thermal reactor: a heater, a quartz window, and an absorber are derived. The control parameters in such a system were the heater temperature and the effective heat transfer coefficients, which characterize the heat removal from the quartz window and the radiation absorber by external agents. The effective heat transfer coefficient, which is responsible for the conductive component of the heat flux from the silicon wafer to the absorber, was also used. Simplified models of the thermal reactor are considered: first, with the quartz window and the absorber with its constant temperature, and second, without the quartz window and with the absorber varying its temperature. It is shown that in the quartz window and absorber there is the effect of induced bistability within the scope of both models. The evolution of a shape of a hysteresis loop is explained at the varying values of the heat exchange coefficients. It is found that temperature jumps of absorber in the instability points of bistable curve for the tungsten heater increases of two orders of value in compared with the heater whose optical properties are that of a blackbody. The explanation of the effect is suggested.

Porous OSG low-k dielectrics deposited by using TEOS and MTEOS mixture with different ratios and Brij® 30 surfactant. The deposited samples contain a different concentration of terminal methyl groups that is proportional to MTEOS concentration. An increase in the methyl groups concentration by changing TEOS/MTEOS ratio decreases the open porosity, k-value, and Young’s modulus and increases the mean pore radius although the template concentration was kept constant. Plasma damage by fluorine radicals depends on the carbon concentration in the films. It can be reduced by 60% when the carbon concentration in the film exceeds 10 atomic percent as measured by XPS (the films deposited with TEOS/MTEOS ratio 40/60).

The study of the selectivity of the plasma etching of functional materials with respect to the mask of a negative electron resist based on hydrogen-silsesquioxane (HSQ) has been carried out. The formation of nanostructures with sub-50 nm critical dimensions by the HSQ mask has been studied for a number of materials: single-crystal silicon, a metallic Ta layer, dielectric layers of SiO₂, Al₂O₃, HfO₂, Si₃N₄, as well as a porous low-k dielectric based on organosilicate glass (OSG) on silicon substrates. It has been found that HSQ resist masks can be used to manufacture prototypes of microand nanoelectronic devices with critical dimensions less than 10 nanometers using a large number of materials, including for creating structures with relatively high aspect ratios with an absolute thickness of layers of functional materials of tens of nanometers.

The modern IC process consists of a 13-layer metallization stack. Critical dimensions are 30-40 nm at the M0- M2 metal layers and due to barrier resistance and electromigration reasons, copper is not the perfect choice nowadays. There are two main alternatives to copper on M0-M2 layers: cobalt and ruthenium. Return to the subtractive scheme could be a powerful solution for future interconnects although the dry etching process of the metal is required for it. In this paper, different approaches to plasma etching of cobalt are studied. CO- and halogen-containing plasmas were considered. It seems that etching in CO-based plasma is inefficient. The rate was only 2 nm/min in a wide temperature range. The low-temperature (60°C) process of the cobalt etching in BCl₃/Ar plasma was developed. The etching rate for the process was 50 nm/min. All of the considered processes are found to be aggressive toward the mask.

It is shown that today one of the priority directions of development of the electronic industry both abroad and in our country is the creation of silicon semiconductor devices and ICs with submicron topological norms, capable of functioning at temperatures of 200 °C and above. It is noted that although in modern ICs aluminum (with additions of silicon and copper) and copper are used as the interconnect material, recently researchers have shown interest in using tungsten as an interconnect material, which is characterized by high electromigration resistance. In the study of the mechanical properties of alloys W with Re, Ti, N films it was found that they are characterized by a reduced level of mechanical stresses compared with the built-in mechanical stresses in the W – Si structure. It was revealed that the alloy films have satisfactory adhesion to silicon and silicon oxide. Tungsten and its alloys films deposited on silicon from the point of view of their use as interconnects in high-temperature silicon ICs, confirmed the prospects for use in VLSI based on a comparative analysis of electrophysical and mechanical characteristics.

The paper presents the results of studying the process of deposition of a Ti-TiN layer coating in a trenches in a silicon substrate. It is shown that one of the promising methods for the deposition of organometallic compounds from the gas phase is MOCVD, characterized by an increased conformity of the film deposition of on a relief surface. The data showing the high-quality filling of trenches in silicon with two-layer Ti-TiN coating are presented.

The paper considers the possibility of the formation of contact plugs filled with copper instead of conventional tungsten (Fig. 1). There are increased requirements for diffusion barrier layers due to the proximity to transistor structures. Several candidate films based on TaN, TiN have been evaluated as diffusion barrier layers in terms of adhesion to copper, electrical properties, and filling contact plug. As a result, device structures with copper contact plugs have been obtained, and corresponding to the specification results have been confirmed.

We discuss the development of a correct theory of Mössbauer spectra of an iron borate single crystal, starting with a simple, but desperately needed technique of correction of any Mössbauer spectrum for the absorber (crystal) thickness, which is followed by the treatment of the Mössbauer spectra in the framework of the Hamiltonian of combined hyperfine magnetic and quadrupole interaction of ⁵⁷Fe nuclei in ground and excited states. The latter results in appearance of two additional spectral lines to a conventional magnetic sextet and describes the specific asymmetry of pairs of lines observed in low-temperature experimental spectra of FeBO₃ crystals. We demonstrate and explain also the characteristic difference in the shape of Mössbauer spectra of the FeBO₃ single crystal and nanoparticles. A drastic difference in the shapes of magnetization curves of the FeBO₃ single crystal and nanoparticles is demonstrated and evaluated in the framework of the generalized Stoner-Wohlfarth model which is extended for antiferromagnetic nanoparticles.

Atomistic simulation with semiempirical Stillinger-Weber potential has been used to study the energetics of strain relaxation in Ge/Si(001) heteroepitaxial system. Several alternative scenarios for misfit strain relief through dislocation nucleation have been investigated. Minimal energy path for each transition trajectory has been found using combination of modified DRAG and Nudged Elastic Band methods. Our results showed that standard 90° Lomer dislocation is the most favorable (global minimum) defect for this heteroepitaxial system. Alternative more complex defects containing two shifted 60° dislocations are indeed also local minima for this system, however corresponding to higher energy states. Their appearance in experiments might be the result of growth kinetics.

Graphoepitaxial CeO₂ and Y:ZrO₂ (YSZ) thin films showed re-orientation towards (012), (013) small-index crystallographic planes (SIPCs) due to surface energy minimization effects, with deviation from the expected tilt angles up to 4.5º. Re-orientation of the CeO₂ films towards the (012) plane was obtained for the intermediate range of deposition rate and oxygen partial pressure, providing high plasticity of the lattice of the film due to formation of oxygen vacancies, and the relatively low bonding strength of the film-substrate interface. The realization of re-orientation of the YSZ graphoepitaxial films demanded intentional suppression of the epitaxial bonding between the film and the substrate. The effect was observed both for (012) and (013) SICPs. The re-orientation is obtained easier when the film experiences additional tilting towards the substrate plane, reaching inclination angles of 2.5-4.5º. The re-orientation from the substrate plane is also possible, but such films are usually re-oriented partially, and the observed inclination angle is limited to ~0.3º. The re-oriented films show a lower spread of orientations of domains, observed as a decrease of the width of the rocking curve. The reason is the co-orienting effect of the substrate surface during growth, opposite to the mis-orienting effect of dislocations generation for ordinary graphoepitaxial films. The lattice constant normal to the epiplane experiences distortion near the surface of the film, contractive for a decrease of the final tilt angle and tensile for re-orientation from the substrate surface.

Molybdenum disulfide (MoS₂) ultrathin films have been deposited onto Si substrates with different deposition parameters by DC-magnetron sputtering (DCMS) using of external magnetic field (MF) to contribute to the improvement of the promising device's characteristics for nano, optoelectronics, plasmonic, and spintronics. The film properties and morphology structure were compared in the case of the MF presence and its absence, varying the pole of the magnet, deposition time, the slope of the substrate holder, and the magnetic induction. The influence of MF on the MoS₂ thin films parameters such as grain size, surface roughness, bandgap energy, was studied by using atomic force microscopy (AFM) and spectrophotometry.

Molybdenum disulfide (MoS₂) thin films with a thickness of about 3.5 nm to 11.5 nm on Si (111) and sapphire (0001) substrates were prepared by the stoichiometric MoS₂ target (99.9% purity) magnetron sputtering. The structure formation features of the thin films were studied by preparing samples under the same deposition conditions and different deposition times 10, 20, and 30 s. Atomic force microscopy (AFM) was used to study the thin film samples' morphological features and revealed various mechanisms of films structure formation on Si and sapphire substrates. For the thin films samples, the reflection spectra obtained and the values of the optical band gap were determined, which ranged from 1.73 to 1.69 eV.

This paper presents results achieved in thin films deposition of hafnium oxide by using the Russian system “Izofaz TM 200-01” developed by the Research Institute of Precision Machine Manufacturing. Tetrakis(ethylmethylamino)hafnium(IV) (TEMAH) and oxygen plasma were used as precursors for atomic layer deposition. Thin films with various thicknesses (100-300 Å) of high uniformity and overall quality were obtained.

In this work, we investigated the influence of the focused ion beams modification modes of the Si substrate local areas on the subsequent growth of GaAs layers by the molecular beam epitaxy. It was found that the crystallization of Ga droplets upon annealing in an arsenic flow does not lead to a significant change in the surface morphology. It was also found the growth of GaAs on substrates with areas modified at an accelerating voltage of 30 kV and subjected to subsequent annealing at a temperature of 800°C results in the formation of nanowires.

The paper shows the experimental results of the substrate temperature effect on the morphological and electro-physical parameters of nanocrystalline BaTiO₃ films fabricated by pulsed laser deposition. It was found increasing in the substrate temperature from 300 °C to 600 °C results in decreasing in surface roughness from (6.1±0.6) nm to (0.8±0.1) nm and increasing in the films grain size from (39.1±3.1) nm to (212.1± 17.2) nm. Increasing in the substrate temperature leads to a change in electro-physical parameters: the concentration of charge carriers increases from (1.85±0.16)×10¹³ cm^-3 to (2.77±0.25)×10¹³ cm^-3, the mobility of charge carriers decreases from (10.1±0.9) cm²/(V·s) to (7.2±0.6) cm²/(V·s), and the resistivity of the films changes insignificantly from (3.4±0.2)×10³ Ω·cm to (3.1±0.2)×10³ Ω·cm under increase in the temperature from 300 °C to 600 °C. The obtained results make it possible to get BaTiO₃ films with target parameters, which can be used to develop promising lead-free energy harvesters for alternative energy devices.

We discuss techniques for analyzing digital elevation models (DEMs) of surface topography of microelectronics objects exemplified by silicon wafers and wafer-based structures, such as SiO₂/Si wafers, silicon–glass assemblies, thin film membranes formed by the Bosch process, and Ni–W films on Bi₂Te₃ substrate. We describe approaches to calculate and analyze wafer curvature using (1) data of curvature of DEM profiles, (2) second partial derivatives computed from DEMs, as well as (3) geomorphometric methods (e.g., analysis of digital models and maps of Gaussian, mean, and principal curvatures as well as other morphometric variables derived from DEMs). We show possibilities of using digital models and maps of catchment area derived from DEMs to analyze location of microcrests of wafer surface. We demonstrate capabilities of these techniques for analyzing volumetric defects. We also present specific recommendations for handling experimental data, such as DEM smoothing by approximation and processing DEMs with voids.

Results of theoretical and experimental surface layers (thickness ranges of 0.1 - 1 angstroms) investigation via X-ray photoelectron spectroscopy (XPS) peak shape analysis are presented. XPS measurements of submonolayer gold coatings on silicon substrate were carried out on two installations: (1) SPECS installation with an energy analyzer capable of recording XPS spectra of photoelectrons emitted in the angular range from 27 to 75 degrees, and (2) KRATOS installation rotating the target to register XPS spectra at angles close to the normal and angles that are about 70 degrees with the normal. Calculations consistently showed a decrease in coating thicknesses with an increase in the viewing angle relative to the normal. The observed effect is described on the basis of a parallelogram island coverage model. This model made it possible to observe the change in the path length distribution function (PLDF) of the emitted photoelectrons depending on the viewing angle. PLDF determines the intensity ratio of the coating and the substrate XPS signals. Results obtained indicate that a series of experiments with angular resolution should be carried out to determine the average effective coating thickness. The value of the critical viewing angle, after which the thickness data are stabilized, is determined by the density distribution of the islands.

This paper suggests a novel method to control quality and reliability of thin dielectric films of the gate dielectric of MIS structures. The proposed method is based on a modification of bounded J-Ramp. This technique, besides the control of charge injected into the gate dielectric until its breakdown, gives a capability to monitor a change of charge state of the gate dielectric during all the test procedure. In order to implement this, after ending of a test (current) step we switch the test current to the measurement current level (Jm) for a short time period and this allows to monitor the voltage change across MIS structure at the constant measurement current density. The current density Jm is chosen to meet the condition that at this level a s significant charge degradation of the dielectric should not be observed. Besides, the switches to measurement level should not greatly influence on bounded J-ramp test procedure. The modified J-ramp method proposes to monitor amount of injected charge, at which irreversible degradation of MIS device characteristics takes place (Qdeg), and evaluate reliability of the dielectric film on the basis of statistical measurements of these quantities.

The necessity of using a vector network analyzer (VNA) for RF/MW device characterization is shown. Field transistor equivalent circuit has been analyzed for dynamic parameters research. Authors have got analytical expressions and provided method for high-frequency field transistors parameters determination based on s-parameters measurements using a VNA. The recommendations for test transistors' optimal parameters are presented. The device under test in this paper is GaAs HEMT double gate transistor with w=150 um. The research of transistors parameters was done in operating point: V_ds=1.4 V, V_gs=-0.6 V. This paper contains method for HEMT transistor capacitance (C_in, C_gd, C_gs) determination using time-domain reflectometry (TDR). Authors have got theoretical and experimental values for f_MAX that show good coincidence.

In this paper we present a new method of calibration of step height standard (SHS) in sub-micrometer range using 3D reconstruction method based on processing of stereo-pair images, acquired by scanning electron microscope (SEM). According to the proposed method, we additionally used a silicon relief structure with approximately the same step height as SHS, and a stylus profiler. The true value of the tilt angle of the SEM specimen stage was measured using an arrangement comprising calibrated prismatic reflective member, mounted on the stage. The analysis of the sources of uncertainty of the step height measurements was carried out.

Mathematical models for three types of beam power calorimeters that do not require calibration are considered. These types are: adiabatic, with a calibrated heat sink, and based on water-flow cooling. For the adiabatic type a transient solution of the corresponding heat transfer equation is presented and its features are considered. Two definitions of the response time are proposed. The question of determining its sensitivity is considered. Based on these definitions, a solution to the problem of the receiving plate material optimal choice in terms of the ratio of sensitivity and response time is proposed. For the type with a calibrated heat sink a simple lumped parameters model is considered. Based of this model estimations of the calorimeter sensitivity and response time were made. For the water-flow type some analytical results following from equations describing its operation within the framework of a quasi-one-dimensional thermal model are presented. A consistent simplification of these equations is considered, which made it possible to obtain simple relationships for assessing the sensitivity, response time, and heating temperature of the receiving plate. A thermal energy balance equation for the stationary mode of operation is obtained. Within the framework of the proposed approach, a rough estimate of the lower boundary of the response time of the water-flow calorimeter was obtained. Wherever possible, comparisons have been made with published experimental and theoretical results. The results obtained can be used for development and design of calorimetric diagnostics systems of fast neutral particle beams.

The boundary value problem for the equation of proton transport in solids is solved on the basis of the invariant imbedding method. The equation obtained for the reflection function (in the small-angle approximation), coincided with the equation that was used for electron scattering and was solved on the basis of the OKG method. The obtained solutions for the reflection functions describe well all the features of the experimental data. Satisfactory agreement of calculations with experimental data is shown.

The relief structure (RS) with vertical sidewalls (SW) is promising as the linewidth measure for low-voltage (LV)SEM due to similarity of its profile to the one of the SCCDRM linewidth standards. So it can be used as the terminal link in the metrological traceability chain beginning from this standard. But there is an obstacle for its calibration: RS image are changing over time during continuous scanning the measure by electron beam that is natural for measure usage. Changes arise from the variation of the emission of slow secondary electrons (SSE) forming the image of the RS surface. This emission variation appears in turn due to the change of induced charge on the RS surface. Changes of the charge disposed near RS edges have critical influence on RS linewidth that leads to its value uncertainty. It is revealed that the degree of the influence depends on the layout of emitting site on RS sidewall (SW). Emission variations from its lower sites have a less induction on the RS image. So if one uses a regime of SSE extraction from these lower SW sites then the linewidth uncertainty is bound to decrease. Internal parts of the vertical SW are preferred not only due to its higher degree of its surface smoothness compared to its upper parts but also due to its SSE emission stability during scanning.

Weintroduce the notion of descriptional complexity of nite-dimensional unitary transformations, which is closely related to the notion of Kolmogorov complexity of a quantum state. In quantum computing, quantum states are associated with quantum data, and unitary transformations of quantum states are associated with quantum computer programs.

Long-distance quantum key distribution (QKD) is a critical component of a quantum network. When network users are within a city, they often use existing telecommunication fiber-optic networks. This method is problematic for QKD on a large scale between cities and countries. Direct connecting of distant consumers with quantum single-photon lines is not possible, because optical fiber involves attenuation. This problem is addressed by constructing a large number of trusted intermediate nodes, but there are concerns with the reliability of each node. To increase the quantum network's dependability, a method of building a satellite quantum network is actively developing. The only one trusted satellite node is required for satellite QKD between any two points on the Earth's surface. Furthermore, a satellite quantum link can also be utilized to add another communication channel in the existing fiber-optic networks that are thousands of kilometers apart. We describe the creation of ground infrastructure elements for receiving single photons in various polarization quantum states from satellites. Ground-based receiving nodes are based on two telescopes with an aperture of 1.2 m and 0.6 m located in remote cities.

Debugging quantum states transformations is an important task of modern quantum computing. The use of quantum tomography for these purposes significantly expands the range of possibilities. However, the presence of preparation and measurement errors complicates the practical use of this procedure. In this work, we investigate the possibility of estimating these errors from experiment. These estimates are subsequently used to build a robust quantum tomography model. The model allows one to accurately reconstruct unitary errors of single-qubit gates. We show that, having such imperfect single-qubit gates with pre-estimated errors, one can obtain transformations close to ideal ones. A similar approach can also significantly mitigate single-qubit gates crosstalk.

The report presents a general approach for estimating quantum information technologies by means of fuzzy quantum measurements. The developed methods are used for precision reconstruction of quantum states under conditions of significant influence of decoherence and quantum noise. Monitoring of the amount of information about quantum states and their parameters, including the loss of information caused by the effect of quantum noise, is considered. Examples of the developed approach as applied to readout errors and phase relaxation are presented.

We propose a composite frequency-scalable quantum memory (QM) scheme based on a system of coupled resonators with single atoms capable of efficient storage of the quantum states of broadband single-photon fields having an arbitrary time form. The analyzed QM consists of 8 high-Q miniresonators coupled to a common resonator that is connected to the external waveguide, where each miniresonator contains a single atom. Based on the methods of optimization of the transfer function, we found the optimal parameters of the QM scheme at which an efficient transfer of a photon wave packet from an external waveguide to the atoms is possible for efficient long-term storage in long-lived atomic states. Various functional modes of using the memory circuit are described and ways to increase efficiency for its use in quantum processing are discussed.

Interaction of quantum system with environment makes the system change its coherent dynamics and it is extremely important to estimate this deviation in correct and clear way. In this paper we consider measure of decoherence based on trace norm. This measure is defined as a maximal norm of the density matrix deviation. We establish the property of additivity at short times: the sum of the individual qubit error measures provides an estimate of the error for a multiqubit system. This property is investigated for 2-qubit systems numerically. Rigorous analytical proof of asymptotic additivity is obtained.

A simple one-qubit algorithm to compute π is considered and compared to another algorithm proposed by Noto with respect to the precision offered and its quantum computation requirements. We find that π = 3:157±0:017 with our algorithm on a real quantum computer and that Noto's algorithm offers accuracy comparable to that, but only on a simulator; heavy use of two-qubit gates would cause Noto's proposed algorithm for calculation of π to perform much worse on quantum computers currently publicly available.

Recently, it was demonstrated¹ that the clustering considered in this articlec, which consists in partitioning a set of data points into subsets depending on the proximity of some properties, can be performed using quantum annealing on a system of two-level quantum elements - qubits. In previous work², we proposed to pass from qubits to qutrits - three-level quantum elements showed the advantages of such a replacement and obtained a time-dependent effective Hamiltonian. In the present paper, we have found a sequence of selective rotation operators that allows one to realize adiabatic evolution with this effective Hamiltonian in the discrete-time approximation. On five qutrits, represented by spins S = 1, we performed a simulation of clustering a set of six points on a plane into three groups by means of quantum annealing.

The spin-1/2 XXZ chain in a uniform magnetic field at thermal equilibrium is considered. For this model, we give phase diagrams for the one-way quantum work deficit (thermal discord). The diagrams can contain regions with both stationary and variable (state-dependent) angles of optimal measurement. We also established a relationship between the behavior of optimal measurement angles near the boundaries separated different regions and Landau’s theory of phase transitions of the second and first kind. Namely, when crossing the boundary from a region with a stationary optimal measurement angle (0 or π/2) to the region with a variable angle of optimal measurement (0 < ϑ < π/2), quantum discord and one-way quantum work deficit experience a sudden change (“catastrophe”) in their behavior. The sudden change is accompanied by a splitting of the minimum characterizing stationary point of quantum correlation into two minima (i.e., bifurcation of the initial single minimum occurs). Such phenomena are analogous to phase transitions described within the Landau theory, or, more generally, by the mathematical formalism of catastrophe theory.

We propose the algorithm for the quantum computer on the IBM Q platform. By this algorithm one can obtain the multiple-quantum NMR dynamics of the dimer with spins 1/2. Our algorithm includes preparation of thermodynamic equilibrium state as initial conditions for dimer and circuit for evolution under the Hamiltonian of multiple-quantum NMR experiment. Multiple-quantum coherences arise in multiple-quantum NMR experiment. Ones are connected with solid body structure and get a lot of research consequently. Intensities of these coherences are measured at end of experiment. In our algorithm the intensities of multiple-quantum coherences are evaluated by tomography of diagonal elements of final density matrix for dimer.

In the paper, we consider using high-dimensional quantum states (so-called qudits) for the implementation of the quantum hashing technique. The importance of qudits for quantum procedures that implement quantum hashing and protocols based on it follows from two considerations. First of all, d-dimensional qudit describes a d-level quantum system, which can be in a superposition of its d basis states without the need of using highly entangled qubit states. The second consideration is that the d-dimensional qudit can be represented by a single particle. These two properties of qudits are considered in this paper to generalize the notion of quantum hashing. The latter is used to present a variant of a quantum protocol for secret key verification.

Recent progress in machine learning has affected almost all areas of the modern economy. The use of quantum protocols to speed up classical machine learning approaches may have further profound effects on society in the future. Here, we developed a hybrid quantum-assisted self-organizing feature map, a type of artificial neural network, and apply it to the data clustering problem in an unsupervised manner. We show that it allows us to reduce the number of calculations in a number of clusters. It is believed that similar types of hybrid quantum classical algorithms can be the main test bed to achieve practical quantum supremacy on Noisy Intermediate Scale Quantum devices.

In this paper, we consider the “Shortest Superstring Problem”(SSP) or the “Shortest Common Superstring Problem”(SCS). The problem is as follows. For a positive integer n, a sequence of n strings S = (s¹, . . . , sⁿ) is given. We should construct the shortest string t (we call it superstring) that contains each string from the given sequence as a substring. The problem is connected with the sequence assembly method for reconstructing a long DNA sequence from small fragments. We present a quantum algorithm with running time O∗(1.728ⁿ). Here O∗ notation does not consider polynomials of n and the length of t.

In this paper, we present the data structure that implements the Self-Balanced Binary Search Tree with strings as keys and quantum comparing procedure. We cannot use the standard Self-Balanced Binary Search because of an error probability for the quantum comparing procedure. We can solve the issue using the standard success probability boosting technique. The presented data structure is more effective (in terms of running time) than using boosting technique. We apply the data structure for the Most Frequently String problem. So, we obtain a quantum algorithm for the problem that is faster than the existing quantum algorithm, and the best classical algorithm in the case of a significant part of the input strings (we mean O(n)) has a length that is at least ω((log n)²). Here n means the number of strings in a collection.

In this work, we consider the performance of using a quantum algorithm to predict the result of a binary classification problem when a machine learning model is an ensemble of any simple classifiers. This approach is faster than classical prediction and uses quantum and classical computing, but it is based on a probabilistic algorithm. Let N be the number of classifiers from an ensemble model and O(T) be the running time of prediction of one classifier. In classical case, the final result is obtained by ”averaging” outcomes of all ensemble model’s classifiers. The running time in classical case is O (N · T). We propose an algorithm that works in
O (√N · T ).

The study of the effect of quantum noise on the accuracy of modeling quantum systems on a quantum computer using the Zalka-Wiesner method is carried out. The efficiency of the developed methods and algorithms is demonstrated by the example of solving the nonstationary Schrödinger equation with allowance for quantum noise for a particle moving in the Pöschl–Teller potential. The analysis and prediction of accuracy for the Zalka-Wiesner method are carried out taking into account the complexity of the quantum system and the strength of quantum noise. In our opinion, the considered problem provides a useful test for assessing the quality and efficiency of quantum computing devices on various physical platforms currently being developed. The obtained results are essential for the development of high-precision methods for controlling the technologies of quantum computations.

Quantum Schrodinger cat states are of great interest in quantum communications and quantum optics. These states are used in various scientific fields such as quantum computing, quantum error correction and high-precision measurements. The analysis of the Schrodinger cat states coherence is an important task for their complete practical application. Our developed approach makes it possible to estimate the coherence of the quantum Schrodinger cat state of arbitrary dimension, as well as to find the interference visibility of the state: an important optical characteristic. The obtained simple quantitative relationship between coherence and the Schmidt number, as well as the developed approach of reducing the multidimensional quantum cat state to a two-mode analog allow us to analyze macroscopic states formed by a large number of modes. Several explicit formulas for the reduced states that arise after measuring of some modes of the considered multimode system are obtained. The research results have significant application and can be used in the development of high-dimensional quantum information processing systems.

The method of quantum tomography, which allows us to track with high accuracy the evolution of multilevel quantum systems (qudits) in Hilbert spaces of various dimensions is presented. The developed algorithms for quantum control are based on the use of the spinor representation of the Lorentz transformation group. In the simplest case of one-qubit states, it turns out that, in addition to three-dimensional rotations on the Bloch sphere, one can introduce four-dimensional Lorentz pseudorotations, similar to the transformations of the special theory of relativity. We show that feedback through weakly perturbing adaptive quantum measurements turns out to be capable of providing high-precision control of the quantum system, while introducing only weak perturbations into the initial quantum state. It turns out that, together with the control of a quantum system through its weak perturbation, the developed algorithms for controlling the evolution of the state of a quantum system can be super-efficient, providing a higher measurement accuracy than any standard POVM (PositiveOperator Valued Measure) protocols. The results of the study are important for the development of optimal adaptive methods for quantum states and operations controlling.

Quantum entanglement is one of the most important measures of quantum correlations. Using group-theoretical approach we found a family of four nine-parameter quantum states for the two-spin-1/2 Heisenberg system in an external magnetic field and with multiple components of Dzyaloshinsky-Moriya (DM) and Kaplan-Shekhtman- Entin-Wohlman-Aharony (KSEA) interactions. Exact analytical formulas are derived for the entanglement of formation for the quantum states found. In the proceeding, the family of found states and the structure of interactions in them are discussed.

The wave plate is a basic device for transforming and measuring the polarization states of light. It is known that the transformation of light by means of two wave plates makes it possible to measure the state of polarization in an arbitrary basis. The finite spectral width of the light, however, leads to a chromatic aberration of the polarization quantum transformation caused by the parasitic dispersion of the birefringence of the plate material. This causes systematic errors in the tomography of quantum polarization states and significantly reduces its accuracy. This study is a development of our work¹, in which an adequate model for quantum measurements of polarization qubits under chromatic aberration was first formulated. This work includes a generalization of the results obtained earlier for the cases of two-qubit states. Along with examples of random states those uniformly distributed over the Haar measure are considered. Using a matrix of complete information, it is quantitatively traced how the presence of chromatic aberrations under conditions of a finite spectral width of light leads to the loss of information in quantum measurements. It is shown that the use of the developed model of fuzzy measurements instead of the model of standard projection measurements makes it possible to suppress systematic errors of quantum tomography even when using high-order wave plates. It turns out that the fuzzy measurement model can give a significant increase in the reconstruction accuracy compared to the standard measurement model.

The present work is devoted to the development of a method for high-precision tomography of ion qubit registers under conditions of limited distinguishability of the states of a logical value 0 and a logical value 1. In the considered ion qubits, the identification of the quantum state is achieved by measuring the fluorescence of the ion by repeated excitation of the cyclic transition, which includes only the lower energy state that sets a logical value 0 and becomes bright, but does not include the upper metastable state that remains dark and sets logical value 1. It is important to note that it is not always possible to achieve low levels of registration errors due to the finite lifetime of excited levels, photon scattering, dark noise, low numerical aperture values, etc. However, even under such conditions, with use of the model of fuzzy quantum measurements, it is possible to provide precise control of quantum states. We show that a model that is characterized by relatively high levels of errors under conditions, where we have a reliable statistical model of their occurrence, is more accurate than the case when the considered errors are small, but we do not have an adequate statistical model for the occurrence of these errors. In the given illustrative examples, we show that the factor of reducing the loss of accuracy with the use of the model of fuzzy measurements can reach values of the order of 1000 or more in comparison with standard measurements.

The obtained results are essential for the development of high-precision methods for controlling the technology of quantum computing on the ion platform.

Quantum tomography is an important tool for obtaining information about the quantum state from experimental data. In this study, we conduct a comparative analysis of various quantum tomography protocols, including protocols based on highly symmetric sets of state vectors, on mutually unbiased bases (MUB), and two-level transformations. Using the universal distribution for the fidelity of quantum state tomography, we estimate the fidelity and efficiency of quantum measurements for qudits of various dimensions as applied to a set of random states uniformly distributed over the Haar measure.

In this work, we present an integrated waveguide-resonator scheme of an atomic quantum transistor with a multi-qubit memory. The quantum transistor is realized in an atomic-photon molecule formed of a linear chain of three interconnected resonators, each of which contains one resonant three-level atom. The resonators are connected through the waveguides to the quantum memory containing long-lived multi-atomic ensembles capable of storage of photonic qubits with an arbitrary temporal mode. We consider the protocols for implementation of one- and two-qubit operations in the proposed scheme over a system of qubits stored in quantum memory. The advantages and experimental implementation of the proposed scheme are also discussed.

In this work, we present a nano-optical scheme of quantum memory for surface plasmon-polariton (SPP) modes in a nanoscale planar waveguide with a resonant atomic ensemble characterized by the periodic structure of the inhomogeneously broadened line. The theoretical study of the SPP modes is presented, where the regime of slow propagation and low-losses was found for these modes with fixed transverse spatial confinement, which provides a strong nondissipative interaction with resonant atoms. We describe the basic physical properties of the studied scheme and demonstrate a perspective area for the implementation of fast nanoscale quantum memory and processing with surface SPP modes.