Negative Photoconductive Effects in Uncooled InAs Nanowire Photodetectors

One-dimensional, direct, and narrow band gap indium arsenide (InAs) nanowires (NWs) have been emerging with great potentials for the next-generation wide-spectrum photodetectors. In this study, metal–semiconductor–metal (MSM) structure InAs NW-based photodetectors were fabricated by transferring MBE-grown NWs onto a sapphire substrate via a mechanical stamping method. These NW detectors exhibit strong negative photoconductive (NPC) effects, which are likely caused by the carrier dynamics in the “core-shell” structure of the NWs. Specifically, under the irradiation of a 405 nm violet laser, the maximum Idark/Ilight ratio reaches ∼102 and the NPC gain reaches 105 at a low bias voltage of 0.2 V. At room temperature, the rise and decay times of InAs NW devices are 0.005 and 2.645 s, respectively. These InAs NW devices with a high Idark/Ilight ratio and NPC gain can be potentially used in the field of vis/near-IR light communication in the future.

The effect of low dose γ-irradiation on the optoelectric properties of n-GaN based MSM structure

The room temperature effect of a low dose rate (10-4 rad (Si)/s) 60 Co γ-irradiation on the structural propertiesand dark current of the GaN-based metal-semiconductor-metal (MSM) structure has been studied. In contrast to previous studies, a non-monotonous dependence of the dark current with the γ-irradiation dose is observed. The intensity and linewidth of the photoluminescence (PL) peaks correlate with the changes in electrical characteristics and eventually degrade after prolonged exposure to the γ-radiation. The abnormal behavior of the MSM structure and particularly its I-V and PL characteristics are explained by considering the carrier transfer mechanism in the localized states. These phenomena are associated with the decrease of shallow donors’ density in localized states and the activation of the non-radiative centers as radiation dose increases. These experimental results and the mechanism presented are essential for understanding the interaction of the γ-irradiation with n-GaN and for estimation of reliability of GaN-based (opto)electronics in harsh conditions of γ-radiation (space applications, liquidation of consequences of technogenic catastrophes, etc.).

Pengaruh Molaritas dalam Teknik Spray terhadap Performa Fotodetektor Berbasis ZnO

ZnO:Fe thin films has been successfully carried out by a simple spray pyrolysis method. The thin film was grown on ITO (Indium Tin Oxide) substrate with a metal-semiconductor-metal (MSM) structure. ZnO:Fe thin film characters as photodetector application include morphological structure, and electrical properties. SEM image results show the molarity difference can affect the particle size. The Current-Voltage (I-V) characterization shows that different solvent effects and molarity give different sensitivity. Sample ZnO:Fe 0.5M Ethanol has the highest sensitivity compared to other samples because it has a fairly low current and high bright current.

Fabrication and Characterization of Graphene Induced Metal Semiconductor Metal (MSM) Structure for Detection and Sensing Applications

The demand for miniaturization of electronic devices has lent to the development of graphene-based hybrid structures, which include the Metal-Semiconductor-Metal device. In this work, we develop such a device by growing monolayer graphene layer on top of Nickel to form the basic structural matrix. Four different variants of the MSM unit structures have been developed to assess their potential in next generation electronics. The presence of graphene in the original matrix was confirmed via Atomic Force Microscopy, and the optical response of the graphene layer was further studied using Spectroscopic Ellipsometry in UV-Vis-NIR regime; Forouhi-Bloomer model was used to analyze the ellipsometry data. Hall effect and other electrical characterization measurements were conducted to analyze the electrical properties of the fabricated devices.

Asymmetric Schottky Contacts in van der Waals Metal-Semiconductor-Metal Structures Based on Two-Dimensional Janus Materials

Physical and electronic asymmetry plays a crucial role in rectifiers and other devices with a directionally variant current-voltage (I-V) ratio. Several strategies for practically creating asymmetry in nanoscale components have been demonstrated, but complex fabrication procedures, high cost, and incomplete mechanistic understanding have significantly limited large-scale applications of these components. In this work, we present density functional theory calculations which demonstrate asymmetric electronic properties in a metal-semiconductor-metal (MSM) interface composed of stacked van der Waals (vdW) heterostructures. Janus MoSSe has an intrinsic dipole due to its asymmetric structure and, consequently, can act as either an n-type or p-type diode depending on the face at the interior of the stacked structure (SeMoS-SMoS vs. SMoSe-SMoS). In each configuration, vdW forces dominate the interfacial interactions, and thus, Fermi level pinning is largely suppressed. Our transport calculations show that not only does the intrinsic dipole cause asymmetric I-V characteristics in the MSM structure but also that different transmission mechanisms are involved across the S-S (direct tunneling) and S-Se interface (thermionic excitation). This work illustrates a simple and practical method to introduce asymmetric Schottky barriers into an MSM structure and provides a conceptual framework which can be extended to other 2D Janus semiconductors.

Full-solution processed all-nanowire flexible and transparent ultraviolet photodetectors

Full-solution processed all-nanowire flexible and transparent UV photodetectors based on a Ag NW/ZnO NW/Ag NW sandwich MSM structure are successfully fabricated and exhibit low operation voltage, excellent photoresponse properties, high transparency and superior mechanical stability.