An open-tube Zn diffusion method that involved the use of solid Zn3P2 or InP was developed, and was used to fabricate heterojunction devices. The diffusion profiles were determined by means of secondary ion mass spectrometry. It was found that the diffusion depth was proportional to the square root of the diffusion time, and that a sharp change in the Zn concentration was observed at the diffusion front. The activation energies were equal to 1.2eV for undoped InP, 1.7eV for Sn-doped InP, and 1.1eV for InGaAs.

T.Ohishi, K.Ohtsuka, Y.Abe, H.Sugimoto, T.Matsui: Japanese Journal of Applied Physics, 1990, 29[2], L213-6