Interdiffusion of Al and Ga in Si-Implanted GaAs–AlAs Superlattices

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Abstract
Interdiffusion in GaAs–AlAs superlattices after Si implantation at 200 keV was studied under various annealing conditions. Interdiffusion of Al and Ga at the GaAs–AlAs interface was not observed before annealing, and compositional disordering due to interdiffusion was found to be controlled by changing the annealing temperature, annealing time, and ion dose. Interdiffusion at the interface followed electrical activation of implanted Si. The interdiffusion coefficients for Al and Ga were estimated to be (2∼5)×10-18 cm2/s and (1∼3)×10-17 cm2/s at annealing temperatures of 750° and 800°C, respectively, in the dose range 2×1013∼2×1014 cm-2. The interdiffusion coefficients were found to increase markedly above a dose of ∼2×1014 cm-2. The results of direct TEM imaging were in good agreement with the predictions from the evaluated interdiffusion coefficients.