A study was made of Al-Ga interdiffusion and C acceptor diffusion in C-doped Ga0.6Al0.4As/GaAs superlattices which had been annealed, under various ambient As4 pressure conditions, at temperatures ranging from 825 to 960C. The superlattices were doped with C to an initial acceptor concentration of about 2.9 x 1019/cm3. The Al-Ga interdiffusion was found to be most predominant in Ga-rich annealing ambients. The interdiffusivity values were about 2 orders of magnitude lower than those predicted by the Fermi-level effect model. In As-rich ambients, the interdiffusion values were in approximate agreement with those which were predicted by the Fermi-level effect model. By analyzing measured hole concentration profiles, it was deduced that both C acceptor diffusion and reduction occurred during annealing. Both the C acceptor diffusivity and the C acceptor reduction coefficient data could be characterized approximately by a ¼-power dependence upon the As4 pressure. These pressure dependences indicated that C diffused via the interstitialcy or interstitial-substitutional mechanism, while hole reduction was governed by a C acceptor precipitation mechanism.

H.M.You, T.Y.Tan, U.M.Gösele, S.T.Lee, G.E.Höfler, K.C.Hsieh, N.Holonyak: Journal of Applied Physics, 1993, 74[4], 2450-60