Mechanisms for Ion and Te-Induced Intermixing of GaAs-AlGaAs Interfaces.

ABSTRACTRecently, GaAs-AlGaAs interfaces have been interdiffused following furnace and rapid thermal annealing (RTA) of samples containing impurities. Two models are proposed to explain the events occurring during the annealing processes. Te was chosen as the impurity for furnace annealing, whereas for the case of RTA, the impurities were introduced via ion implantation. The Te-induced interdiffusion process is modeled using an ensemble Monte Carlo simulation. The results of the simulation are in good agreement with the Te intermixing data. In the case of ion implantation followed by RTA, the intermixing model is based on the solution of coupled diffusion equations involving the excess vacancies and the Al distribution 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 excess interstitials calculated in the simulation are coupled to the vacancy diffusion via a phenomenological decay constant. Having established the value of the decay constant from one set of experimental results, the model is able to predict accurately other independent experimental results.