A new technique, which involved a Zn3P2 diffusion source and rapid thermal annealing, was studied. A p+-type layer could be obtained only at temperatures of between 500 and 550C by using a 15s diffusion time. The diffusivity was calculated and was compared with the results of furnace annealing. The present diffusivity was deduced to be equal to 2.6 x 10-12cm2/s. In order to form a shallow layer, it was necessary to avoid any treatments which might redistribute Fe or dopants. Annealing (850C, 15s) before diffusion shifted the carrier profile from 300 to 600nm in depth. The second diffusion front extended to 0.0024mm in a semi-insulating substrate. Diffusion treatments which were performed on samples without pre-annealing resulted in 2 diffusion fronts. A 0.0028mm-deep second diffusion front was found when the treatment was applied to a pre-annealed epi-wafer. The diffusivity under these conditions was deduced to be equal to 1.4 x 10-11cm2/s.

K.W.Wang, S.M.Parker, C.L.Cheng, J.Long: Journal of Applied Physics, 1988, 63[6], 2104-9