Time-domain finite difference and EMC study of hot carrier transport in GaAs on a picosecond scale

It is now possible to use optoelectronic techniques to generate and measure electrical waveforms with subpicosecond risetimes. Though experimental methods have become relatively advanced, simulation techniques for analyzing and modelling such ultrafast transients remain inexact and oversimplified. The simplifications commonly made while developing equivalent circuit models for the experimental structures, prevent accurate simulation of the electrical response during the picosecond regime. In order to obtain a better physical picture, it is essential to develop a more physical model for the microstrip circuits routinely used in such experiments. Furthermore, non-Ohmic transport behavior for the photogenerated carriers within the optoelectronic device also needs to be correctly incorporated. We address both the circuit and device response issues through a novel scheme which combines direct time domain solutions to Maxwell's equations with the ensemble Monte Carlo model for carrier transport. By coupling the electromagnetics with the EMC, we avoid having to make assumptions whose validity breaks down for picosecond transport.