The δ-doped samples were grown by using molecular beam epitaxial methods, and were analyzed by using high-resolution secondary ion mass spectrometry. It was found that there was a marked difference between the profiles which were produced from samples that had been doped to a surface density of less than 1.3 x 1013/cm2 (where all of the Si was incorporated on Ga sites), and highly-doped samples (where auto-compensation occurred). All of the samples were grown at a nominal temperature of 580C, and all of the doped planes showed some degree of broadening. A computer model for a 2-step diffusion process was developed, and this predicted a set of diffusion coefficients for lightly-doped samples. The diffusion coefficient which was associated with the post-deposition growth of these lightly-doped samples was about 4.2 x 10-17cm2/s. Because of their complicated profiles, more highly-doped samples were modelled by using a graphical technique. This revealed the presence of a much larger diffusion coefficient, which was tentatively attributed to the diffusion of Si as nearest-neighbor pairs.

An Investigation of the Diffusion of Silicon in Delta-Doped Gallium Arsenide, as Determined using High-Resolution Secondary Ion Mass Spectrometry. H.C.Nutt, R.S.Smith, M.Towers, P.K.Rees, D.J.James: Journal of Applied Physics, 1991, 70[2], 821-6