This PDF file contains the front matter associated with SPIE Proceedings Volume 7364, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Theoretical analysis of the electron energy spectrum and the magnetization in a strained In_xGa_1-xAs/GaAs selfassembled quantum ring (SAQR) is performed using realistic parameters, determined from the cross-sectional scanning-tunneling microscopy characterization. The Aharonov-Bohm oscillations in the persistent current have been observed in low temperature magnetization measurements on these SAQRs. The effect of the Coulomb interaction on the energy spectra of SAQRs is studied for rings with two electrons and with an exciton. Our analysis of the photoluminescence spectrum in magnetic fields up to 30 T shows that the excitonic properties strongly depend on the anisotropic shape, size, composition and strain of the SAQRs and is in a good agreement with the experimental data.

The atomic force acoustic microscopy (AFAM) technique combines the principle of atomic force microscopy (AFM) for nanoscale imaging with the ability to detect changes in elastic modulus on a tested sample. Depending on the mode of operation, AFAM provides qualitative and quantitative information on the effective stiffness of the probed sample either in the form of images or point measurements. AFAM is a contact based method and as such provides information on the sample indentation modulus from a volume that is compressed under the AFM tip. The size of the compressed volume depends on the static load applied to the tip, tip radius, and the elastic properties of the tip and the probed sample and thus it can be controlled. The AFAM technique can be a powerful tool for characterization of thinfilm systems and detection of defects that are buried at a depth of about 30 nm - 150 nm. We used the AFAM method to study various nano-thin systems. A set of nine square membranes 3.7 μm x 3.7 μm large, with thickness increasing in 30 nm steps from 30 nm to 270 nm was dry etched in silicon. AFAM qualitative images obtained on the surface of this sample showed all the membranes allowing for their localization. In addition, we used AFAM to determine indentation modulus of silicon oxide films M_f with the thickness varying from 7 nm to 28 nm. The values obtained for M_f varied from 80 GPa to 90 GPa and were in good agreement with the literature values.

Positive and negative charges are stored locally in thin films of silicon oxide on silicon by applying a voltage between an AFM cantilever tip and the silicon substrate. The stored charges are displayed by Kelvin probe force microscopy (KPFM). The process of charge storing is investigated with respect to different dwell times and different voltages. The amount of stored charges increases both with applied voltage and dwell time. A decay mechanism of the charges with two different time regimes is discussed. A fast decay is attributed to a migration parallel to the surface, while the second one is dominated by a transport perpendicular to the substrate surface.

Structural, magnetic, and magneto-transport properties in C:Ni (30 at.%) nanocomposite films grown by ion beam cosputtering at 500 °C are investigated by means of transmission electron microscopy, superconducting quantum interference device magnetometry and electrical transport measurements. The C:Ni film shows a superparamagnetic behavior with a large coercivity field of 250 Oe at 5 K compared with bulk Ni metals. Anomalous Hall effect is observed in C:Ni nanocomposites, which is attributed to the scattering of spin-polarized carriers by the magnetic Ni nanoparticles in the carbon matrix.

We report the creation of nano-structures via Dip Pen Nanolithography by locally exploiting the mechanical response of polymer thin films to an acidic environment. Protonation of cross linked poly(4-vinylpyridine) (P4VP) leads to a swelling of the polymer. We studied this process by using an AFM tip coated with a pH 4 buffer. Protons migrate through a water meniscus between tip and sample into the polymer matrix and interact with the nitrogen of the pyridyl group forming a pyridinium cation. The increase in film thickness, which is due to Coulomb repulsion between the charged centers, was investigated using Atomic Force Microscopy. The smallest structures achieved had a width of about 40 nm. Different control experiments support our claim that the protonation is the reason for the swelling and therefore the formation of the structures. Kelvin probe force microscopy measurements suggest the presence of counter ions which compensate the positively charged pyridinium ions. We investigated the influence of the water meniscus on the structure formation by varying the relative humidity in the range from 5% to 60% for different dwell times. The diffusion of protons and counter ions is humidity-dependent and requires a water meniscus.

We report on the functionalization of silicon oxide nanostructures using luminescent dye molecules and the characterization of these systems by optical microscopy. The nanostructures are prepared by local anodic oxidation (LAO) of a dodecyl-terminated silicon substrate using an atomic force microscope (AFM). The silicon oxide nanostructures are negatively charged and the cationic dye rhodamine 6G could be successively bound to the structures by electrostatic interactions. A quenching of luminescence due to the interaction of the excited states with the silicon was found. The luminescence signal is attributed to monomeric Rh6G molecules with a slight blue shift of the emission due to the changed chemical environment.

The collection, selection, amplification and detection of minimum genetic samples became a part of everyday life in medical and biological laboratories, to analyze DNA-fragments of pathogens, patient samples and traces on crime scenes. About a decade ago, a handful of researchers began discussing an intriguing idea. Could the equipment needed for everyday chemistry and biology procedures be shrunk to fit on a chip in the size of a fingernail? Miniature devices for, say, analysing DNA and proteins should be faster and cheaper than conventional versions. Lab-on-a-chip is an advanced technology that integrates a microfluidic system on a microscale chip device. The "laboratory" is created by means of channels, mixers, reservoirs, diffusion chambers, integrated electrodes, pumps, valves and more. With lab-ona- chip technology, complete laboratories on a square centimetre can be created. Here, a multifunctional programmable Lab-on-a-Chip driven by nanofluidics and controlled by surface acoustic waves (SAW) is presented. This system combines serial DNA-isolation-, amplification- and array-detection-process on a modified glass-platform. The fluid actuation is controlled via SAW by interdigital transducers implemented in the chemical modified chip surface. The chemical surface modification allows fluid handling in the sub-microliter range. Minute amount of sample material is extracted by laser-based microdissection out of e.g. histological sections at the single cell level. A few picogram of genetic material are isolated and transferred via a low-pressure transfer system (SPATS) onto the chip. Subsequently the genetic material inside single droplets, which behave like "virtual" beaker, is transported to the reaction and analysis centers on the chip surface via surface acoustic waves, mainly known as noise dumping filters in mobile phones. At these "biological reactors" the genetic material is processed, e.g. amplified via polymerase chain reaction methods, and genetically characterized.

In the paper, we present the experimental data that demonstrate the conductance decrease with bias in the tunnel Al/GaAs Schottky structure with delta-n-doped 2D channel. The conductance is decreasing due to the increase in the tunnel-barrier height and the corresponding drop in the barrier tunnel transparency with bias. Theoretical calculations are in very good agreement with the experimental data, they also show that the mechanism should lead to the negative value of the differential conductance, if the separation between the subbands in the 2D channel is sufficiently large. The Al/InAlGaAs/InAlAs and Ti/GaN/AlGaN heterostructures with tunnel Schottky-barriers are suggested, where the negative differential conductance should be achievable.

We propose a simple design of a rotary nanomotor comprised of three quantum dots attached to the rotating ring (rotor) in the presence of an in-plane dc electric field. The quantum dots (sites) can be coupled to or decoupled from source and drain carrier reservoirs, depending on the relative positions of the leads and the dots. We derive equations for the site populations and solve these equations numerically jointly with the Langevin-type equation for the rotational angle. It is shown that the synchronous loading and unloading of the sites results in unidirectional rotation of the nanomotor. The corresponding particle current, torque, and energy conversion efficiency are determined. Our studies are applicable both to biologically-inspired rotary nanomotors, the F₀ motor of ATP synthase and the bacterial flagellar motor, which use protons as carriers, and to novel artificial semiconductor systems using electrons. The efficiency of this semiconductor analog of the rotary biomotors is up to 85% at room temperature.

The preparation of (sub)monolayers of small and short-chain organic molecules on oxide-covered silicon is described. The molecular end groups and their chemical reactions were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, spectroscopic ellipsometry (IR-UV), laserinduced desorption of monolayers (LIDOM), X-ray photoelectron spectroscopy (XPS), and contact-angle experiments. Surface species were identified and their reactions were monitored by FTIR analysis of characteristic vibrational modes. This includes bottom-up synthesis of siloxane chains, diverse reactions of double bonds, and specific molecular transformations such as the Diels-Alder reaction. Layer thicknesses could be estimated with a sensitivity of ~0.02 nm and accuracy of ~0.05 nm by oxidation of the hydrocarbons. This was achieved by in situ real-time detection of the corresponding thickness changes by spectroscopic ellipsometry. From time-of-flight (TOF) experiments, which provided the desorption temperature and mass of the emitted species, the thermal stability, chemical transformation, and fragmentation pattern of chemisorbed species could be extracted. To analyze the hydrophilic or hydrophobic nature of functionalized surfaces the surface energy and wettability were determined.

Multilayer structures based on matrices of CdSe and CdSe/ZnS nanoparticles in polyimide (PI) and poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were prepared and investigated. A comparison of photoluminescence of the various matrices excited by visible and ultraviolet laser radiation was carried out. The main contribution to the photoluminescence was made by the organic semiconductors. Quantum yield of the luminescence of CdSe nanoparticles embedded in organic semiconductor matrix was found to be lower then that of the individual CdSe nanoparticles dispersed onto a glass substrate. This difference was shown to be a result of charge transfer from the nanoparticles to organic molecules. The nanoparticles were responsible for photovoltage in thin layers of the PI/nanoparticles composites. Processing of a surface of electrodes and organic semiconductors by oxygen plasma increased the photovoltaic efficiency.

We make use of electron beam lithography (EBL) and reactive ion etching (RIE) techniques to realize periodic masks with elements of nanometric size. Epitaxial growth of Si layers and SiGe alloys on or through such a mask leads to the formation of structures such as quantum dots and quantum rings. We will show that by making use of EBL and RIE it has been possible to obtain preferential sites for the nucleation of Ge islands on Si(001). EBL has been optimized in order to obtain circular pits with diameters ranging from 80 to 200 nm and depth from 30 to 80 nm. AFM images of the patterned substrates confirm the regularity and reproducibility of patterning in terms of form and dimension. The subsequent deposition of a thin film of Ge results in the nucleation of Ge islands at preferential sites. The precise positioning of Ge islands may be an optimal solution for obtaining self-assembled and well-ordered Ge nanostructures, leading to a number of new applications, for example within the field of quantum computing.

Mesoscopic structures are important for photonics applications. Here we describe the preparation of honeycomb films with pore diameters of 3 to 7 μm from a crosslinkable polymer by the breath-figure technique, which involves the evaporation of a solution of the solute at high humidity. The honeycomb films then were used as templates for less-thendense packing of microspheres or for the adsorption of nanocrystalline inorganic oxides. Application of the strongly light scattering and highly porous honeycomb films are in the field of photocatalysis.

Crystalline silicon / organic thin film heterojunction based solar cells have been realized using spin-coating deposition. Devices with different organic films, all based on PEDOT:PSS, which in some cases have been mixed with double-walled or multi-walled carbon nanotubes, have been compared. Highest conversion efficiencies have been obtained either with a highly conductive PEDOT:PSS emitter withut nanotubes or with a nanocomposite emitter consisting of low conductive PEDOT:PSS emitter mixed with multi-walled carbon nanotubes. Using the nanocomposite emitter, rather high values for the solar cell shunt resistances have been obtained without any etching procedure in order to improve the lateral current confinement. A comparison with a Schottky diode, realized as reference device by the evaporation of the top metal contact directly on top of the crystalline silicon substrate, showed that the heterodiode characteristics was not dominated by leakage current paths and short circuits through the organic layer.

Extreme Ultraviolet Lithography (EUVL) is a leading lithography technology for the sub-32 nm chip manufacturing technology. Photomasks, in a mask carrier or inside a vacuum scanner, need to be protected from contamination by nanoparticles larger than the minimum feature size expected from this technology. The most critical part with respect to contamination in the EUVL-system is the photomask. The protection is made more difficult because protective pellicles cannot be used, due to the attenuation of the EUV beam by the pellicle. We have defined a set of protection schemes to protect EUVL photomasks from particle contamination and developed models to describe their effectiveness at atmospheric pressure (e.g. in mask carriers) or during scanning operation at low pressure. These schemes include that the mask is maintained facing down to avoid gravitational settling and the establishment of a thermal gradient underneath the mask surface to thermophoretically repel particles. Experimental verification studies of the models were carried out in atmospheric-pressure carriers and in a vacuum system down to about 3.3 Pa. Particles with sizes between 60 (for experiments, isn't it 125 nm?) nm and 250 nm were injected into the vacuum chamber with controlled speed and concentration to validate the analytical and numerical models. It could be shown that a deterministic approach using free molecular expressions can be used to accurately describe particle deposition at these low pressure levels. Thermophoresis was found to be very effective at both atmospheric and low pressure against the diffusional particle deposition, whereas inertial particle deposition of large and/or fast particles can likely not be prevented. A review of the models and their verification will be presented in this paper.

We performed a set of non-contact measurements using scanning probe microscope at room temperature such as Kelvin probe measurements and measurements of local differential capacitance of single-walled carbon nanotubes (SWCNT) doped with CuI. SWCNT with essential deviated values of work function were observed with Kelvin probe measurements. Deviations of work function we attribute to the presence and of CuI impurities and their peculiarities of structure. Differential capacitance measurements demonstrated absence of the essential decrease of the conductivity because if of CuI dopant.

Nucleation and annihilation of vortices at antidots as well as their guided motion between antidots are of the key issues in the current efforts to design methods for controlling the vortex manipulation in micropatterned thin films. An adaptive numerical approach has been developed on the basis of the time dependent Ginzburg-Landau equations in order to describe the generation and motion of vortices in YBCO films with antidots. Numerical analysis was performed of the distributions of the order parameter and the current density in superconducting films with different patterns of antidots (up to 32). The optimisation of the guided motion of vortices requires data on the specific distributions of the current density and the order parameter in samples with large number of antidots.

A Fabry-Perot-type interferometer is experimentally realized for electrons in a semiconductor device. Interference conditions are created for co-propagating electrons in quantum Hall edge states, which results in oscillations of the current through the device for integer and fractional filling factors. We find the interference oscillations in transport across the incompressible strips with local filling factors ν_c = 1, 4/3, 2/3 even at high imbalances, exceeding the spectral gaps. In contrast, there is no sign of the interference in transport across the principal Laughlin ν_c = 1/3 incompressible strip. This indicates, that even at fractional ν_c, the interference effects are caused by "normal" electrons. The oscillation's period is determined by the effective interferometer area, which is sensitive to the filling factors because of screening effects.