A study of Cu diffusion in both p-type and n type samples showed that this material exhibited a transition to semi-insulating behavior at relatively low Cu diffusion temperatures. It was found that all, or most, of the Cu precipitates formed a Cu-In compound, that both originally n-type and p-type material became semi-insulating, and that there was a negligibly low concentration of deep-level defects. It was observed that there was an abnormal reduction in both electron and hole mobilities, which resulted from the introduction of Cu, and that there were isolated pockets of highly conductive material in otherwise semi-insulating material. It was concluded that all of these experimental observations could be best explained by the buried Schottky barrier model instead of compensation by deep levels.

R.P.Leon, M.Kaminska, K.M.Yu, Z.Liliental-Weber, E.R.Weber: Materials Science Forum, 1992, 83-87, 723-8