Self- and interdiffusion in AlXGa1−XAs/GaAs isotope heterostructures

We report self- and interdiffusion studies between 800 and 1160 °C in buried Al71GaAs/Al69GaAs/71GaAs and AlAs/71GaAs isotope heterostructures. Ga diffusion at Al71GaAs–Al69GaAs interfaces was found to decrease with increasing Al content. Al–Ga interdiffusion at AlGaAs–GaAs and AlAs–GaAs interfaces reveals a concentration dependent interdiffusion coefficient. The temperature dependence of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs is described by a single activation enthalpy in the range of 3.6±0.1 eV, but with different pre-exponential factors. The experimentally observed higher Al diffusion in GaAs compared to Ga self-diffusion as well as the decreasing Ga diffusion with increasing Al content is explained.