Transferred electron effects in n-GaAs and n-InP under hydrostatic pressure

Experimental results are presented showing the variation of the peak velocity, electric field at peak velocity and saturated velocity of the velocity-field curve for bulk n-GaAs under hydrostatic pressure. Similar data are presented for the field at peak velocity for bulk n-InP. The extraction of the data from the current-voltage characteristics is based on an exploitation of the influence of boundary conditions on the manifestation of transferred-electron induced (Gunn) current instabilities. Our results, which differ from those of other investigations, are compared with our Monte Carlo calculations of the velocity-field curves for these materials. We find that ionized impurity scattering plays an important role in the understanding of our data.     

Computer calculations of the efficiency of the Gunn generator

The dependences of the efficiency of the Gunn generator on the diode and régime parameters are investigated with the help of the computer model of the Gunn diode. The dependences of the efficiency on the parameters of the diode and the frequency dependences of the efficiency are given.     

Calculation of the parameters of the microwave Gunn generator

The scheme of the calculation of the microwave parameters of Gunn generators is proposed. The calculation lets us express the microwave parameters using physical parameters of the diode and can be used for the determination of the optimal operation régime of the Gunn diode in a resonator.     

Novel multilayer modulation doped (Al,Ga)As/GaAs structures for self-aligned gate FETs

The fabrication of self-aligned gate by ion implantation modulation doped (Al,Ga)As/GaAs field effect transistors (MODFETs) utilising a novel multilayer structure capable of withstanding the high-temperature furnace anneals required for Si implant activation is reported. Typical measured extrinsic transconductances of 175 mS/mm at 300 K and 290 mS/mm at 77 K were achieved on 1.1 ?m-gate-length devices. Values of the two-dimensional electron gas saturation velocity of 1.9×107 cm/s at 300 K and 2.7×107 cm/s at 77 K were obtained from an analysis of the FET drain current/voltage characteristics using the charge-control model.     

AlGaN/GaN metal oxide semiconductor heterostructure field effecttransistor

We report on the AlGaN/GaN metal oxide semiconductor heterostructure field effect transistor (MOS-HFET) and present the results of the comparative studies of this device and a base line AlGaN/GaN heterostructure field effect transistor (HFET). For a 5-μ source-to-drain opening, the maximum current was close to 600 mA/mm for both devices. The gate leakage current for the MOS-HFET was more than six orders of magnitude smaller than for the HFET     

Design criteria for GaAs MESFETs related to stationary high field domains

Using a modified theory of the high-field domains which takes into account the field-dependent diffusion we show that the existence of the high-field domain at drain side of the gate in GaAs MESFETs leads to a new set of design criteria which should be met to achieve the optimum performance. We derive these criteria and estimate the drain-to-source breakdown voltage and the maximum power of the device as functions of the doping density and device dimension. We also estimate the optimum gate length, the thickness of the active layer, the drain-to-gate separation and the doping level as functions of frequency. It is demonstrated that a larger than conventional drain-to-gate separation might be necessary for power devices to house a fully developed highfield domain and to avoid a premature breakdown at the drain. Our estimates indicate that the maximum power at 10 GHz can reach a theoretical limit of about 20 watts for class A operation.     

Composition and submicron structure of thin films of supersaturated Zn x Pb1 − x S solid solutions

Thin films of supersaturated Zn _x Pb_{1 ? x} S solid solutions containing up to 4.1 mol % ZnS have been obtained by hydrochemical deposition. The dependence of the material structure and surface morphology on the film composition has been studied. It is established that an increase in the content of zinc sulfide leads to the growth of grains with a more complicated crystalline structure, the formation of grain boundary fragments with dimensions from 60 to 100 nm, and a modification of the electrical properties of deposited layers.