Cation vacancy formation and migration in the AlGaAs heterostructure system

A simple experimental approach has been employed to obtain thermochemical p arameters for cation vacancy formation and migration in the AlGaAs heterost ructure system. Cation vacancies are injected into the free surface by anne aling under an arsenic-rich ambient. Their presence is detected by monitori ng the local rate of Al-Ga interdiffusion at imbedded quantum well markers. The sample is unusually thick allowing us to separately identify contribut ions from the vapor, epilayer, and substrate phases. The entropies and enth alpies of vacancy formation and migration are (5.2 +/- 5.7) k(B) and (1.8 /- 0.5) eV and (11.3 +/- 4.4) k(B) and (3.3 +/- 0.4) eV, respectively. (C) 1998 American Institute of Physics. [S0003-6951(98)02051-8].