Ideal Current-voltage Characteristics Research Articles

Model Study on the Ideal Current–Voltage Characteristics and Rectification Performance of a Molecular Rectifier under Single-Level-Based Tunneling and Hopping Transport

As a fundamental unit of molecule-based electronics, a molecular rectifier is one of the most widely studied molecular devices, of which the ideal current–voltage (I–V) characteristics based on a t...

Atomic scale modeling of electrically doped p-i-n FET from adenine based single wall nanotube

The Field Effect Transistor (FET) characteristics has been observed from a single-walled Adenine nanotube device using Density Functional Theory associated with Non Equilibrium Green’s Function based First Principle approach. This device is electrically doped which shows both n and p channel characteristics of a p-i-n FET. This device is designed and originated from a single-walled biomolecular nanotube structure. The p and n regions have been induced at the two ends of the device using electrical doping process. Thus both n and p channel current-voltage response can be obtained within a single nano-scale device at room temperature operation. The device is 3.35nm long and 1.4nm wide. The quasi-ballistic quantum transmission property reveals impressive and almost ideal current-voltage characteristics of the FET. Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) gap reveals the possibility of quasi-ballistic coherent transmission of the device. The electronic properties based on Molecular Projected Self-consistent Hamiltonian are analyzed using Hilbert space spanned basis functions. The maximum tunneling current observed for the bio-molecular FET is 15.9μA for n-channel and 13.8μA for p-channel. The device is operated in atomic scale regime with 1000THz frequency. The present results reveal the role of quantum-ballistic tunneling phenomenon in the current-voltage characteristics and channel conductance properties of the bio nanotube structure, which is useful in future generation nano-electronics.

Characteristics of deep traps in freestanding GaN

AbstractDeep traps in a 300-m m-thick freestanding GaN sample were characterized by deep level transient spectroscopy (DLTS), using Schottky barrier diodes (SBDs) fabricated on the Ga polarity surface. Most of the SBDs show nearly ideal current-voltage characteristics, with both forward and reverse currents controlled by the thermionic emission mechanism. Five common traps, which include A1 (1.0 eV), A (0.66 eV), B (0.59 eV), C (0.35 eV), and D (0.25 eV), can be consistently observed in all SBDs. Two of them, A1 and C, are related to surface damage. Surprisingly, some new traps can be found in the DLTS spectra of some SBDs if higher reverse biases are used in the measurements. However, they cannot be fitted by DLTS simulations, and are likely associated with parasitic capacitance somewhere in the cryostat.

InGaP/InGaAsN/GaAs NpN double-heterojunction bipolar transistor

We have demonstrated a functional NpN double-heterojunction bipolar transistor (DHBT) using InGaAsN for the base layer. The InGaP/In0.03Ga0.97As0.99N0.01/GaAs DHBT has a low VON of 0.81 V, which is 0.13 V lower than in a InGaP/GaAs heterojunction bipolar transistor (HBT). The lower turn-on voltage is attributed to the smaller band gap (1.20 eV) of metalorganic chemical vapor deposition-grown In0.03Ga0.97As0.99N0.01 base layer. GaAs is used for the collector; thus the breakdown voltage (BVCEO) is 10 V, consistent with the BVCEO of InGaP/GaAs HBTs of comparable collector thickness and doping level. To alleviate the current blocking phenomenon caused by the larger conduction band discontinuity between InGaAsN and GaAs, a graded InGaAs layer with δ doping is inserted at the base–collector junction. The improved device has a peak current gain of seven with ideal current–voltage characteristics.

Ultrahigh efficiency obtained with GaAs-on-insulator MESFET technology

Significant results of measurement and calculation of power-added efficiency (PAE) and drain efficiency are presented for MESFET's that use GaAs-on-insulator. Ultrahigh PAE of 89% was obtained at 8 GHz with a gain of 9.6 dB using a 3-V supply. When the voltage was increased to 4 V, the peak PAE was 93% at 210 mW/mm with 9.2-dB gain. The ideal current-voltage characteristics with practically zero leakage current and large transconductance near pinchoff yielded PAE values approaching the theoretical limits of overdriven operation. The application of conventional assumptions concerning drain efficiency is discussed relative to devices that approach these theoretical limits. Also discussed are the pitfalls of various figures of merit of efficiency when applied to these devices. Hence, there are two types of technical barriers associated with very-high-efficiency devices: the physical realization and their characterization.

Silicon diffused diodes with nearly ideal current-voltage characteristics

It is shown that nearly ideal current-voltage characteristics (I-V curves) can be obtained for small-area, shallow silicon diffused p-n junctions irradiated with 60Co gamma rays in the dose range 103–5×105 Gy. In the irradiated diodes the current transfer mechanism is observed to shift from generation-recombination to diffusion. The nonideality factor on the forward branch of the I-V curve decreases from 1.68 in the unirradiated diode to 1.17 in a diode irradiated to a dose of 5×105 Gy. A saturation current is observed on the reverse branch of the I-V curves of irradiated diodes at room temperature.

Single SiC/Si heterostructure negative-differential-resistance diode for resistive-fuse applications

A novel resistive-fuse with near ideal current-voltage characteristics has been successfully implemented by using a single SiC/Si heterostructure negative-differential-resistance (NDR) diode. This novel resistive-fuse possesses several advantages, including its simple structure and fabrication process, very low current levels in off-operation, and the potential for high-temperature operation.

Influence of defects upon the forward bias admittance of metal-semiconductor interfaces

Static and dynamic electrical properties of several metal-semiconductor interfaces in which the metal thickness is a few hundred or thousandÅare analysed. First, admittance measurements have been made under forward bias in two types of Al/n-GaAs contacts. The Al and n-GaAs layers have been prepared by molecular beam epitaxy on an n +-GaAs wafer. In the first type, which shows ideal current-voltage characteristics, only an inductive effect is observed. Such a result cannot be fitted by any effect attributable to interface states but rather by minority carrier injection into the bulk semiconductor. In the second type, differing only in the n-GaAs surface which was prepared under inferior vacuum conditions, non-ideality of current-voltage characteristics and excess capacitances are both seen. The back contact being the same in both types of samples, the onset of excess capacitance must be related to the change in the defect density near the interface. Second, polycrystalline YSi 1.7/Si samples are studied. For all these imperfect metal/semiconductor contacts, the capacitance measured under forward bias shows behavior which can be explained by the existence of states lying within the band gap of the semiconductor and in equilibrium with the majority carrier band.

Admittance of Al/GaAs Schottky contacts under forward bias as a function of interface preparation conditions

Admittance measurements have been made under forward bias on two types of Al/n-GaAs contacts. The Al and n-GaAs layers have been prepared by molecular beam epitaxy on an n+-GaAs wafer. In the first type, which shows ideal current-voltage characteristics, only an inductive effect was observed and no effect attributable to interface states was detected. In the second type, differing only in the n-GaAs surface which was prepared under inferior vacuum conditions, nonideality of current-voltage characteristics and excess capacitances were both seen. The back contact being the same in both types of samples, the onset of excess capacitances must be related to the change in surface characteristics. A model which assumes a U-shaped density of extrinsic interface states accounts simultaneously for the behavior of conductance, capacitance, and ideality factor as functions of temperature, voltage, and frequency.

Fermi level and current transport of Bi12GeO2

A photoelectrochemical resistor was constructed using a bismuth germanium oxide electrode and a liquid junction. Current transport consists of the oxidation and reduction of water by holes and electrons, and the device exhibits ideal current voltage characteristics with a ratio of light to dark current greater than 104. By comparison of the flat-band potential in the dark and under irradiation it is concluded that the intrinsic Fermi level of our sample is in the center of the band gap at −310 mV vs SCE (pH=5). Deep trap levels at 0.20 and 0.33 eV above the valence band can be present in varying concentrations and facilitate the trapping and recombination of electrons and thereby decrease conductivity.