Simulation of the impact of stress induced piezoelectric charge in GaAs MESFETs

Abstract

This work presents the methodology involved in applying numerical electronic device simulation, and specifically, the application of this methodology to the study of piezoelectric effects in GaAs MESFETs. Firstly, a three-dimensional (3D) numerical simulation package EVEREST, developed for the simulation of silicon electronic devices, has been enhanced by the introduction and verification of models for GaAs device physics. Then a 2D finite element program for the simulation of mechanical stresses in the MESFET structure and a program for the extraction of piezoelectric charge from the numerically calculated stresses have been produced. The force load model applied to the metal/dielectric/GaAs structure is suggested as a good mathematical representation of the physical processes involved. The impact of stress induced piezoelectric charge, substrate doping and varying gate length on the electrical characteristics of epitaxial and ion-implanted MESFETs have been determined by numerical simulation using the EVEREST device simulator. Comparison between experimental data and simulation results has been presented. Finally, conclusions and suggestions for further study have been given.