A simple experimental approach was used to deduce thermochemical parameters for cation vacancy formation and migration in this system. Cation vacancies were injected into the free surface by annealing in an As-rich ambient. Their presence was detected by monitoring the local rate of Al/Ga interdiffusion at embedded quantum-well markers. The sample was unusually thick, and permitted the separate identification of contributions from the vapor, epilayer and substrate phases. The entropies and enthalpies of vacancy formation and migration were 5.2k and 1.8eV and 11.3k and 3.3eV, respectively.

Cation Vacancy Formation and Migration in the AlGaAs Heterostructure System. P.Mitev, S.Seshadri, L.J.Guido, D.T.Schaafsma, D.H.Christensen: Applied Physics Letters, 1998, 73[25], 3718-20