Current-voltage characteristics of metal-titanium dioxide-silicon structures

Metal-titanium dioxide-silicon capacitors were fabricated using electron- beam-evaporated titanium dioxide as the insulating layer. The effects of the titanium dioxide deposition conditions and post-deposition oxidation on the current-voltage characteristics were investigated. A time-dependent current was observed and modeled. Diffusion of the titanium from the titanium dioxide layer into the p-type silicon substrates during oxidation of the titanium dioxide film resulted in an n-type diffused layer. Leakage current densities as low as 10^-9 A in^-2 at 10 V applied bias were obtained for a 1000 Å film of titanium dioxide.     

Current-voltage characteristics of thin-film gas sensor structures based on tin dioxide

The experimental current-voltage (I–U) curves of thin-film structures based on tin dioxide (SnO₂) exhibit nonlinearity in the range of strong applied electric fields. The results of I-U measurements are interpreted within the framework of a model that assumes the drift of adsorbed ions over the film surface. The observed phenomenon can be used both for detecting the impurities in air and for recognizing the types of adsorbed species.     

Novel GaAs current-injection negative differential resistance transistor

GaAs current-injection negative differential resistance transistors using n⁺-i-p⁺-i-n⁺ structure prepared by molecular beam epitaxy are presented. For p⁺ with a sheet concentration of 10¹³ cm^–2, a negative differential resistance region is revealed for a base currentI _B<100 µA. The peak to valley current ratios are about 8 at room temperature. This is proposed to be due to the bipolar-unipolar transition reaction. WhenI _B>=100 µA, the proposed device operates as a conventional bipolar transistor.     

Current-voltage characteristics of a four-terminal superconducting weak link

The current-voltage characteristics of a new type of Josephson-like junction consisting of four superconductors in connection with a common region via separate weak links are investigated. This arrangement permits strong interaction and proximity effects to occur inside the composite junction, and the observed variations in theI–V curves can be explained mainly in terms of an exchange of dc and ac quasiparticle currents between phase-slip centers. In particular, direct frequency locking among three Josephson oscillators and induced dc voltage in an unbiased junction have been found for the first time. These effects are of interest for considerations of developing large-scale integrated superconducting circuits.     

Current-voltage characteristics and emf of an electric-arc heater operating with various gases

The stationary and dynamic current-voltage characteristics of an electric-arc heater with an argon, nitrogen, air, and oxygen stabilized arc are determined. An empirical expression for calculating the currentvoltage characteristics for various working gases is proposed.     

Current-voltage characteristics of a three-phase one-chamber alternating current plasmatron

A method for the determination of the current-voltage characteristics of a one-chamber three-phase industrial-frequency plasmatron is considered. The form of the characteristics is set proceeding from general laws governing a gas flow past an arc; a numerical value of the coefficients entering these characteristics is calculated with account of the data obtained in the experiment.     

Current-voltage characteristics of nanodimensional normal metal-superconductor point diffusion junctions

The differential conductivity of nanodimensional normal metal-superconductor (NS) point diffusion junctions has been calculated with allowance for partial breakage of the superconducting state by the intrinsic current in the superconducting electrode and for the Andreev reflection at the adaptive N’S interface. Dependence of the excess current and the differential conductivity on the applied voltage are considered.     

Observation of negative differential resistance and single-electron tunneling in electromigrated break junctions

We observed a negative differential resistance (NDR) along with single-electron tunneling (SET) in the electron transport of electromigrated break junctions with metal-free tetraphenylporphyrin (H₂BSTBPP) at a temperature of 11 K. The NDR strongly depended on the applied gate voltages, and appeared only in the electron tunneling region of the Coulomb diamond. We could explain the mechanism of this new type of electron transport by a model assuming a molecular Coulomb island and local density of states of the source and the drain electrodes.     

Transport model of controlled molecular rectifier showing unusual negative differential resistance effect

We investigate theoretically the charge accumulated Q in a three-terminal molecular device in the presence of an external electric field. Our approach is based on ab initio Hartree-Fock and density functional theory methodology contained in Gaussian package. Our main finding is a negative differential resistance (NDR) in the charge Q as a function of an external electric field. To explain this NDR effect we apply a phenomenological capacitive model based on a quite general system composed of many localized levels (that can be LUMOs of a molecule) coupled to source and drain. The capacitance accounts for charging effects that can result in Coulomb blockade (CB) in the transport. We show that this CB effect gives rise to a NDR for a suitable set of phenomenological parameters, like tunneling rates and charging energies. The NDR profile obtained in both ab initio and phenomenological methodologies are in close agreement.     

结构动力响应微分求积分析方法的基本特性

以结构动力响应微分求积(DQ)分析方法的基本数值格式为基础,探讨了时步内时间点分别为均匀分布、Chebyshev分布和Chebyshev-Gauss-Lobatto(CGL)分布时该方法的数值稳定性与数值耗散性,并通过等效一阶模型严格推导出方法的代数精度阶数。研究表明,该方法的数值稳定性与时步内时间点分布情况密切相关,不均匀分布格式明显优于均匀分布格式,但体系阻尼比对方法的稳定性具有重大影响;代数精度由离散时间点数决定,一般情况下都能实现比较高的数值精度;两种不均匀时间点分布格式,即Chebyshev格式和CGL格式的DQ分析方法,均具有极佳的数值耗散特性。     

Current-voltage characteristics of molecular conductors: two versus three terminal

Addresses the question of whether a "rigid molecule" (one which does not deform in an external field) used as the conducting channel in a standard three-terminal MOSFET configuration can offer any performance advantage relative to a standard silicon MOSFET. A self-consistent solution of coupled quantum transport and Poisson's equations shows that even for extremely small channel lengths (about 1 nm), a "well-tempered" molecular FET demands much the same electrostatic considerations as a "well-tempered" conventional MOSFET. In other words, we show that just as in a conventional MOSFET, the gate oxide thickness needs to be much smaller than the channel length (length of the molecule) for the gate control to be effective. Furthermore, we show that a rigid molecule with metallic source and drain contacts has a temperature independent subthreshold slope much larger than 60 mV/decade, because the metal-induced gap states in the channel prevent it from turning off abruptly. However, this disadvantage can be overcome by using semiconductor contacts because of their band-limited nature.     

Current-voltage characteristics from an asymptotic analysis of the MOSFET equations

Phenomenological formulae for the current-voltage characteristics of a MOSFET are derived by extending the asymptotic method of Ward. Practical methods for combining the perturbation approximations and numerically implementing the Ward equations are developed. A detailed comparison with real MOSFET data is presented and the model is shown to be effective over a range of device geometries.     

Current-voltage characteristics of organic photovoltaic cells following deposition of cathode electrode

The current-voltage characteristics of benzoporphine-fullerene solar cells were measured subsequent to the deposition of Al as a cathode material. Even in vacuum, a shift in the open circuit voltage was observed at 20 min after Al deposition. Moreover, the displacement of inert gases (N(2)or Ar) in the evaporation chamber enhanced the photovoltaic parameters. The power conversion efficiency was increased by 24% over the initial characteristics (from 1.04% to 1.29%), which indicates that the structure of the organic-metal interface changed rapidly after Al deposition, even if the process was performed in an air-free glovebox.     

Interface-induced negative differential resistance and memristive behavior in Gr/MoSe2 heterostructure

Journal of Materials Science: Materials in Electronics - Heterostructures of materials can possess the prominent characteristics of their individual layers or gain newly emerged interface effects...