A wafer of InP, with an evaporated thin layer of metallic Zn, was used as a diffusion source and was placed 0.15mm away from the sample. In this way, it was possible to obtain good diffusion-front planarity, perfect surface quality, and a free-hole concentration of about 8 x 1018/cm3. It was suggested that the first stage of the diffusion process was characterized by the incorporation of a large quantity of Zn, such that interstitial Zn atoms compensated the acceptors. The Zn concentration then levelled out, but most of the interstitials left the crystal. Due to the small free volume which existed between sample and source, P loss was decreased and the formation of P vacancies was diminished.

T.Krieghoff, E.Nowak, G.Kühn, B.Schumann, A.Höpner: Crystal Research and Technology, 1992, 27[1], 49-57