A sealed-tube method was used to prepare Zn-diffused layers, using both Zn3P2 and Zn+InP as sources, at 500C. The diffusion times ranged from 300s to 2h. Both S-doped and Zn-doped crystals were used as substrates. The Zn depth profile was measured by using secondary ion mass spectroscopy, while the lattice strain which was produced by diffusion was investigated by means of X-ray double crystal diffractometry and the standing-wave method for recording photo-electrons. The results showed that, in S-doped crystals, the diffused/virgin interface was very sharp and the diffused layers were lattice-contracted. The concentration of Zn, as well as the lattice strain, did not depend upon the diffusion time whereas the thickness of the diffused layer increased with time. A plot of diffused layer thickness versus the square root of the diffusion time exhibited differing slopes, depending upon the diffusion source. Both the lattice strain and the diffusion depth depended upon the diffusion source, whereas the Zn concentration was not affected by the type of diffusion source. The results were explained by taking account of differences in the gas-phase composition and the induced diffusion mechanisms. The Zn3P2 source appeared to be more appropriate since it led to both faster diffusion and lower lattice strains in the diffused layer.

Structural Properties of Zn-Diffused InP Layers. C.Bocchi, P.Franzosi, C.Pelosi, A.V.Maslov, E.K.Mukhamedzhanov, N.Gambacorti, M.G.Simeone, R.Audino: Journal of Applied Physics, 1997, 82[11], 5416-21