It was pointed out that Be was one of the main p-type dopants which were used for the fabrication of devices that were based upon GaAs or related III-V materials. The element dissolved substitutionally on the group-III sub-lattice, and diffused via a kick-out mechanism which involved group-III self-interstitials. Non-equilibrium concentrations of these self-interstitials had a marked effect upon the diffusivity of Be. Various situations were considered in which non-equilibrium point defects played a role in Be diffusion. These included the in-diffusion of such dopants from an external source, the diffusion of grown-in dopants, self-interstitial generation by Fermi-level surface pinning, and recombination-enhanced Be diffusion during device operation. It was noted that the diffusion behavior of C, which was found on the group-V sub-lattice of GaAs, was much less sensitive to non-equilibrium point defects. It was therefore used to replace Be as a p-type dopant.

M.Uematsu, K.Wada, U.Gösele: Applied Physics A, 1992, 55[4], 301-12