Study of the interdiffusion of GaAs-AlGaAs interfaces during rapid thermal annealing of ion-implanted structures

Abstract

The phenomenon of transient-enhanced interdiffusion of GaAs-AlGaAs interfaces during rapid thermal annealing of ion-implanted heterostructures is studied. It is shown that the important properties that influence the degree of interdiffusion are the temperature, the concentration of excess vacancies, and the ability of the vacancies to diffuse freely. A model is presented to explain these observations; it is based on the solution of coupled diffusion equations involving excess vacancy and Al distributions following ion implantation. Both initial distributions are obtained from the solution of a three-dimensional Monte Carlo simulation of ion implantation into a heterostructure sample. The model is found to be in excellent agreement with several sets of experiments. More specifically, it is shown to be valid for as-implanted vacancy concentrations below 6×1019 cm−3.