UNSTABLE BEHAVIOR OF GA ATOMS IN ZNSE EPITAXIAL LAYERS

Using ion-channeling methods, the thermal stability of crystallinity f or heavily Ga-doped ZnSe epitaxial layers grown on GaAs (100) substrat es was investigated. Some distinctive features were found: The crystal linity of as-grown heavily Ga-doped ZnSe is similar to that of undoped ZnSe. After thermal annealing at 450 degrees C, the crystallinity of Ga-doped ZnSe is degraded, although that of undoped ZnSe is not signif icantly changed. It is expected that doped Ga atoms are displaced from the regular lattice sites after annealing. The degree of this degrada tion depends on the crystallinity of the as-grown Ga-doped ZnSe itself , These results indicate the degradation of the crystallinity for Ga-d oped ZnSe epilayers is mainly caused by the interaction between the do ped Ga atoms and grown-in point defects In the epitaxial layers. (C) 1 997 American Institute of Physics.