NbSe2, serving as a 2D metal electrode, has been proven to form a Schottky heterojunction with MoSe2 to realize a highperformance broadband photodetector. Here, we further investigated the effect of gate voltage on the optoelectronic characteristics of the device. The results revealed that NbSe2 exhibits a weak electrostatic screening effect similar to graphene, and due to the high-quality contact between the 2D metal and semiconductor, the rectification ratio of the device can be significantly modulated from 0.32 to 5.5×104. Regarding the photovoltaic response characteristics of the device, the gate voltage similarly achieves significant modulation of the short-circuit current (20 nA-1.6 μA), open-circuit voltage (0-0.32 V), maximum electrical power (0-210 nW). Furthermore, the response speed of the device is also influenced by the gate voltage. This work demonstrates that Schottky heterojunctions constructed based on 2D metals can achieve effective control of optoelectronic properties, and has encouraging prospects in the fields of optical communications, optical sensing, and imaging.
In the field of electronic modulation, vanadium dioxide (VO2) is a potential material owing to its function of automatic insulator-to-metal transition (MIT) which can induce rapid changes in electrical resistivity through MIT. Nevertheless, the application of modulator based on VO2 is limited by some performance shortcomings, including wide hysteresis loop width (ΔH), high phase transition temperature (Tc) as well as low phase transition amplitude (AMIT). In this work, by DC (DirectCurrent)-magnetron sputtering with doping Fe3+ into VO2 films, narrowed ΔH and decreased Tc are observed. Interestingly, the Fe doped VO2 films show ultra-high phase transition amplitude despite the low Tc due to the influence of Fe dopants. Specifically, the 0.5% Fe-doped VO2 film shows the best MIT characteristics with ultra-high phase transition amplitude of 104, narrow ΔH decreased to 9.8° and low Tc around 60.02°C, which is considered to be the first time to highly heighten the electrical MIT properties by Fe doping. In addition, we also comprehensively studied the influences of doping with Fe element on the MIT properties and microstructures based on characterization such as SEM, XRD, Raman shift and XPS results. These results show that our unique preparation method can manufacture VO2 thin films with excellent MIT properties, which will be beneficial to the popularization and publicity of VO2 based electrical modulator.
Lead sulfide colloidal quantum dots, similar to the nanoscale crystals of most semiconductor crystals, are available in a variety of sizes, shapes, and compositions as well as to make different chemical molecular ligands to modify the surface of the quantum dots and to fabricate functional optoelectronic devices on a variety of substrate materials. The combination of silicon and colloidal quantum dots enables the fabrication of silicon-based compatible quantum dot optoelectronic devices over a wide range of applications. In this paper, the effects of channel doping concentration and channel length on the performance of silicon-based CQD/Si photodetectors are calculated and analyzed from the simulation method. The results show that a suitable doping concentration and a short channel length can improve the performance of the device, which provides a simulation basis for the fabrication of silicon-based compatible arrayed colloidal quantum dot photodetectors.
The Switching mechanism of a-Si memristor is based on the electrochemical metallization (ECM) effect. After application of a constant bias, the metal ions oxidized on the surface of the electrode migrates to the amorphous silicon layer, which not only lead to the resistive switching behavior, but also the change of optical parameters of switching material. Here, a novel film memristor with optical readout functionality has been set up by combining a silicon prism with Ag/a-Si/Al structure. The attenuation of the reflected light from the device dependence on surface plasmon resonance (SPR) effect on interface of silver layer which is sensitive to the refractive index of the a-Si layer. The change of the reflectance spectrum of the memristor under different bias voltages was simulate by means of finite-difference time-domain (FDTD) method, and the influence of the thickness of the amorphous silicon film and the silver film on the intensity of the reflected light was analyzed.
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