Papers by Keyword: Current-Voltage Characteristic

Abstract: Solid polymer electrolyte (SPE) produces hydrogen and oxygen from pure water uses electrochemical reaction, and this process is believed to be the most promising and efficient way to produce hydrogen. For application and simulation, the electrical model of SPE is absolutely required, we intend to develop an electrical model. Where the model has been constructed based on the structure and characteristics of SPE. The electrical model of SPE battery like that consists of a voltage and resistance, that fulfil the equation v=1.936+ 0.0183I-0.013T, to ensure that this model is close to the character of the SPE, we conducted an experiment to validate it, based on the correlation analysis method we obtained those results of the experiment and results of calculation of the model have a correlation is > 0.9988, this meaning that the model is valid.

Abstract: The paper presents the route of manufacturing transistors on gallium nitride. As a result of the work done, prototypes of transistor crystals with a gate length and width of 0.5 μm and 0.8 mm, respectively. The basic static characteristics are presented.

Abstract: In this paper we present the results of investigation of heterostructures with an array of InAs quantum dots grown on GaAs substrates with GaAs and AlGaAs front barriers for high-speed near-IR photodetectors. The thickness of the barrier layers did not exceed 30 nm. It is shown that the ion-beam deposition method makes it possible to grow quantum dots with lateral dimensions up to 30 nm and 15 nm height. The spectral dependences of the external quantum efficiency and dark current-voltage characteristics are investigated.

Abstract: The change in the current-voltage characteristics and in N_d-N_a values in the base of 4H-SiC Schottky diodes and JBS diodes under irradiation with 0.9 MeV electrons and 15 MeV protons has been studied. The carrier removal rate for the diodes irradiated with electrons was 0.07-0.15 cm^-1, and that in the case of protons, 50-70 cm^-1. It was shown that the devices under study retain rectifying current-voltage characteristics up to electron doses of ~10¹⁷ cm^-2. It was found that the radiation resistance of the SiC-based devices significantly exceeds that of silicon p-i-n-diodes with similar breakdown voltages. The simultaneous effect of high temperature and proton irradiation on the characteristics of 4H-SiC pn structures was examined.

Abstract: We prepared n-type nanocrystalline iron disilicide (NC-FeSi₂)/intrinsic (i) ultrananocrystalline diamond/amorphous carbon composite (UNCD/a-C)/p-type Si heterojunctions and evaluated as photodiodes. UNCD/a-C and NC-FeSi₂ films were deposited by coaxial arc plasma deposition and pulsed laser deposition, respectively. The capacitance-voltage and current-voltage characteristics of heterojunctions were measured at room temperature. The inserted i-UNCD/a-C layer to form pin heterojunctions reduced the capacitance and dark current as compared with those in the case of pn heterojunctions. The build-in potential of heterojunctions was estimated to be 1.2 eV. The prepared heterojunctions showed typical rectifying action and a response for an illumination with a 6 mW, 1.31 μm laser. The recombination process is the predominant mechanism of current transport in the heterojunctions. The dynamic resistance area product and detectivity were 1.54 × 10³ Ω cm² and 5.0 × 10⁸ cmHz^1/2/W at-1 V. The evident improvement in the device performance was demonstrated, which should be due to the reduction of dark current by i-UNCD/a-C layer.

Abstract: Preparation of n-type β-FeSi₂/intrinsic Si/p-type Si heterojunctions was accomplished by facing-target direct-current sputtering (FTDCS) and measuring their current-voltage characteristic curves at low temperatures ranging from 300 K down to 50 K. A mechanism of carrier transport in the fabricated heterojunctions was investigated based on thermionic emission theory. According to this theory, the ideality factor was calculated from the slope of the linear part of the forward lnJ-V plot. The ideality factor was 1.12 at 300 K and increased to 1.99 at 225 K. The estimated ideality factor implied that a recombination process was the predominant mechanism of carrier transport. When the temperatures decreased below 225 K, the ideality factor was estimated to be higher than two and parameter A was estimated to be constant. The obtained results implied that the mechanism of carrier transport was governed by a trap-assisted multi-step tunneling process. At high forward bias voltage, the predominant mechanism of carrier transport was changed into a space charge limit current process.

Abstract: Mesa structural n-type nanocrystalline-FeSi₂/p-type Si heterojunctions were successfully fabricated by a lift-off technique combined with a photolithography process. Their current-voltage characteristics were measured at low temperatures range from 300 K down to 60 K. We estimated their diode parameters such as ideality factor, barrier height and series resistance based on the thermionic emission theory and Cheung’s method. From the estimation by the thermionic emission theory, the obtained results show an increase of ideality factor and a decrease of barrier height at low temperatures. The estimation by Cheung’s method shows that the values of ideality factor and barrier height are in agreement with those obtained from the thermionic emission theory. The obtained series resistances from dV/d (lnJ)-J and H(J)-J plots, which are approximately equal to each others, are increased at low temperatures.

Abstract: n-Type β-FeSi₂/p-type Si heterojunctions have been successfully fabricated by facing-targets direct-current sputtering at a substrate temperature of 600 °C without post-annealing and their current-voltage characteristics were measured at low temperatures ragne from 300 K down to 50 K. The ideality factor, saturation current and series resistance were estimated by the thermionic emission theory and Cheung’s method. By the thermionic emission theory, we calculated the ideality factor from the slope of the linear part from the forward lnJ-V and estimated the saturation current density from the straight line intercept of lnJ-V at a zero voltage. As decreasing temperatures from 300 down to 50 K, the value of ideality factor increased from 1.2 to 15.6, while the value of saturation current density decreased from 1.6 × 10⁻⁶ A/cm² to 3.8 × 10⁻¹⁰ A/cm². From the plots of dV/d (lnJ)-J and H(J)-J by Cheung’s method, the obtained values of series resistances are consistent with each other. The series resistances analyzed from both plots increased as decreasing temperatures.

Abstract: TO/ZnPcSu-PCBM/Al heterostructure was prepared by ink-printing and studied by DC (current-voltage characteristics) and AC (dielectric spectroscopy) techniques (ZnPcSu means 3-diethylamino-1-propylsulphonamide substituted Zn phthalocyanine, PCBM phenyl-C61-butyric acid-methylester fullerene). At the Al contact a Schottky barrier was formed. To explain the shape of current-voltage characteristic two effects had to be taken into account, emission effect, overcoming the potential barrier effect, formed by the superposition of the image Coulombic, space-charge and external potentials, by charge carrier. Dielectric spectroscopy made possible to determine effective lifetime of charge carriers and characteristic time related to electron diffusion; lifetime of charge carriers was τ_d = 2.10^-5 s, and the electron mobility was of order 10⁴ cm²V^-1s^-1.

Abstract: The ZnO thin film structures were obtained by MOCVD method under atmospheric pressure onto Si substrates heated up to 250-350 оС. The film thickness varied from 0.4 – 0.5 µm. The phase composition, structure and morphology of ZnO films as well as electrophysical properties of ZnO/Si heterojunction on their base were investigated. The possible charge flow mechanisms in ZnO/Si heterojunction are discussed.