Modeling of Al/Ga interdiffusion in AlAs/GaAs superlattice materials

AlAs/GaAs superlattice (SL) disordering experiments were performed at 800 degrees C and 900 degrees C for different periods of time to study Al/Ga interdiffusion. SUPREM-IV.GS was used to model these interdiffusion results and extract the Al/Ga interdiffusivity values for each anneal condition. The extracted Al/Ga interdiffusivity values match well with the values reported by the other groups, and over a limited range they appear to be composition-independent. Using Darken's analysis and treating the AlAs/GaAs SL material as a nonideal solution, ALAMODE was used to model our SL disordering results explicitly. From the simulation we extracted the Al self-diffusivity, which can be described as D-Al=1.25x10(-3)xexp(-3.49eV/kT) in the temperature range between 800 degrees C and 900 degrees C. The extracted Al self-diffusivity value is close to the extracted Al/Ga interdiffusivity but different from the Ga self-diffusivity.