A three dimensional semiconductor device simulator for GaAs/AlGaAs heterojunction bipolar transistor analysis

A three-dimensional semiconductor device simulator was developed to study the steady-state characteristics of heterostructure compound semiconductor devices. The semiconductor partial differential equations-Poisson´s equation and the two carrier transport equations-are solved using finite-difference discretization. The Gummel iteration method and indirect space matrix solution techniques are utilized for minimizing computation time and memory requirements. This simulator was applied to the analysis of heterojunction bipolar transistors. The effect of emitter grading on the current-voltage characteristic is demonstrated. A comparison between two- and three-dimensional simulations is also presented. The results show that three-dimensional analysis is indispensable, in particular for devices of small geometry