Formation of semi-insulating InP through metallic Cu-rich precipitates

A set of diffusion experiments of Cu in InP have shown that this semiconductor exhibits a transition to semi-insulating behavior after relatively low Cu diffusion temperatures. The study described here involves structural, ion-beam/channeling, magnetic, and electrical measurements. It was observed that most or all of the Cu precipitates form a Cu-In compound, that both originally {ital n}- and {ital p}-type InP become semi-insulating upon Cu diffusion, and that there is a negligible concentration of deep-level defects in Cu-doped InP. Further observations include an abnormal reduction in both electron and hole mobilities resulting from the introduction of Cu, and the occurrence of isolated pockets of conductive InP in otherwise semi-insulating material. The concurrence of these experimental observations can best be explained using the buried Schottky-barrier model instead of the commonly observed compensation by deep levels.