Defects in ZnSe metalorganic chemical vapor deposited epitaxial hetero-epilayers, on GaAs substrates, were investigated by using mono-energetic positrons. It was found that there were marked differences between as-grown specimens, and those which had been heat-treated in various atmospheres. As-grown specimens which had been prepared at 350C exhibited a large number of defects near to the surface, and at the GaAs interface. These defects were attributed to the effects of lattice mismatch and non-stoichiometry. Heat-treatment at 70C, in N2, introduced high concentrations of vacancies which contributed to the deep emission of photoluminescence. It was concluded that heat treatment in Zn vapor was required in order to reduce the concentration of native defects in the present materials.

L.Wei, Y.K.Cho, C.Dosho, S.Tanigawa, T.Yodo, K.Yamashita: Japanese Journal of Applied Physics, 1991, 30[10], 2442-8