Diffusion of Cd into InP at 680°C

Cadmium was diffused into undoped at 680°C using elemental mixtures of (Cd,In) and (Cd,P) as starting sources. The depths of the p‐n junctions were determined as a function of the Cd‐activity, , of the (In,Cd) alloys, and as a function of the amount of P. The variation of the junction depth with phosphorus vapor pressure indicates the formation of Cd compounds which are the actual diffusion sources on the P‐rich side. The diffusion of Cd in is interpreted based on the largely accepted interstitial‐substitutional model. The charge states of the diffusing interstitial species and the substitutionally incorporated Cd appear to depend on the diffusion conditions. On the In‐rich side, at , the diffusing interstitial is neutral and Cd is mostly present as a monovalent acceptor. At , the diffusing interstitital is doubly ionized and Cd is incorporated as a monovalent acceptor. On the P‐rich side, the data suggest a doubly ionized Cd‐interstitial as the diffusing species with the Cd largely present in a neutral form.