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An empirical velocity‐field relationship, based on Monte Carlo simulation, is used to modify a drift‐diffusion model for the characterization of short gate GaAs MESFET's. The modified drift‐diffusion model is used to generate both the steady‐state and the small‐signal parameters of submicron GaAs MESFET's. The current, transconductance, and cutoff frequency are compared with two‐dimensional Monte Carlo simulation results on a 0.2 µm gate‐length. The model is also used to predict measured I‐V and s‐parameters of a 0.5 µm gate‐length ion‐implanted GaAs MESFET. The comparison and the analysis made, support the accuracy of the modified drift‐diffusion simulator and makes it computationally efficient for analysis of short‐gate devices.

A computer model of silicon‐on‐sapphire MESFETs has been developed in order to help the construction and technology work of novel complementary MES digital circuit building blocks. The modelling work is based partly on physical simulation by solving the semiconductor partial differential equations, and partly on development of a large‐signal MESFET model with an arbitrary doping profile input, implemented on a nonlinear circuit analysis program. The results showed cover investigations of both DC and transient behaviour of CMES inverters.

A quasi‐two‐dimensional analytical model for GaAs MESFETs is proposed. It enables the calculation of the dc, the small‐signal, and the noise behaviour of GaAs MESFETs and takes into account both doping and low‐field mobility profiles in the active layer of the transistor. It is shown that the profile of the low‐field mobility near the bottom of the active layer has a considerable influence on the minimum noise figure.

The current‐voltage (Id—Vd) characteristics and microwave performance of Si1−xGex MESFETs are discussed. The 2D Poisson's equation along with the drift and diffusion equation are solved using a finite difference technique to calculate device parameters such as gm and fT. The low field carrier mobility is computed by using a single partice Monte Carlo program. In the simulation all relevant scattering mechanisms are accounted for.

A two‐dimensional numerical computer simulation based on the analysis of the first three moments of the Boltzmann equation, known as the energy‐transport model, has been used to study various two‐dimensional effects on the performance of AlGaAs/GaAs heterostructure field‐effect transistor. The results are presented for half‐micron gate length. The calculation reveals significant electron current contribution coming from the AlGaAs region between the source and gate, contributing to the reduction of access resistance. As the electrons acquire large energies near the drain side edge of the gate, real‐space transfer to the AlGaAs region from the “two‐dimensional” electron gas channel occurs. However, at the drain end, the electron current is confined at the GaAs side of the heterointerface. The result shows insignificant current contribution from regions of depth greater than 0.048 µm into the undoped GaAs bulk. At room temperature, the results indicate transconductance, current gain cutoff frequency and power density about twice that which are calculated for “equivalent” GaAs MESFET, of identical structure and doping level as the heavily‐doped AlGaAs region. These results suggest that HEMT devices have the potential for providing significant sources of power at millimeter‐wave frequencies.

The response of a MESFET and an inverted HEMT to the impact of an a particle has been calculated by means of the Monte Carlo Particle Model, a technique for solving Boltzmann's transport and Poisson's field equation self‐consistently in space and time. The calculations show that all the terminals of the MESFET react by generating an initial current pulse followed by another; the timing of the second pulse depends on the angle of incidence of the α particle. The lattice heating rate was found to be largest at the corners of the Ohmic contacts. The HEMT, on the other hand, hardly reacts electrically to the α particle but is more likely to burn out in an a particle radiation environment because of the larger lattice heat generation taking place in the interior of the transistor. The results also support the theory of the hot‐electron induced subsurface catastrophic failure mechanism.

Uses a streamline‐diffusion finite element method, specially designed for semiconductor device models, to simulate silicon MESFET devices in two space dimensions. Considers the full hydrodynamic model, a simplified hydrodynamic model and drift‐diffusion model. The method, which reduces to the well‐known Scharfetter‐Gummel discretization for the conventional drift‐diffusion model in one space dimension, proves to be a robust numerical tool. It performs well also when the solution has layers of rapid variation across junctions which are not aligned with mesh lines. Makes comparisons for the different models. Finds a qualitative discrepancy between the solutions of the hydrodynamic model and the drift diffusion model. Observes a small difference, however, between the full and simplified hydrodynamic models.

A transport model has been developed which is reasonably accurate, and has proven quite efficient for the two‐dimensional numerical simulation of submicron‐scale Si and GaAs devices. In this model an approximate form of the energy‐transport equation is developed; this equation is easily included in otherwise‐conventional device simulation codes, which then require only slightly more solution time than standard models using field‐dependent transport coefficients. Calculations for 0.25 micron gate length Si and GaAs MESFET's show that velocity overshoot effects can be very important, particularly in the latter material; predicted saturation currents in the GaAs devices are almost three times larger than those that would have been predicted using conventional transport models. The model described, and its application in simulation programs, should find use in the design of submicron‐scale devices to properly take advantage of overshoot phenomena.

An simple model for the simulation of the electrical behaviour of several types of junction controlled field‐effect transistors is proposed. It is based on the calculation of the carrier concentration in the channel by means of a self‐consistent solution of Schrödinger and Poisson's equation in the direction perpendicular to the current flow. Based on the carrier concentration the dc, the small‐signal, and also the noise properties of the devices may be simulated. The calculated characteristics of a sub‐quarter micron gate GaAs MESFET, a δ‐doped GaAs FET and a Velocity Modulation Transistor will be presented and discussed.

A hydrodynamic semiconductor device simulator, DYNA, is introduced. A new relaxation time evaluation scheme for two‐valley semiconductors is proposed to account for the dependence of the electron mobility on the impurity scattering. Some robust solution methods are used in the simulator for treating the highly nonlinear system of equations. The simulation results for a nonuniformly‐doped GaAs MESFET are also shown.