Compositional As–Sb intermixing was studied, using transmission electron microscopy, in GaAs films which had been grown by molecular-beam epitaxy at low temperatures and δ-doped with Sb. Calibration permitted the estimation of the effective As–Sb interdiffusion coefficient from the apparent thickness of Sb δ-layers in films which were isochronally annealed at 400 to 600C. The As–Sb intermixing in low-temperature GaAs was found to be appreciably enhanced when compared with conventional material. The temperature dependence (figure 1) could be described by:

D (cm2/s) = 2 x 10-14 exp[-0.62(eV)/kT]

Since the kick-out mechanism which operated under equilibrium conditions was valid for As–Sb interdiffusion in GaAs, the enhanced intermixing was attributed to the over-saturation of As self-interstitials in the low-temperature GaAs films. The effective activation energy for As–Sb interdiffusion in low-temperature GaAs seemed to be reasonably close to the migration enthalpy of As interstitials, and their concentration was estimated to be about 1018/cm3.

Enhanced As–Sb Intermixing of GaSb Monolayer Superlattices in Low-Temperature Grown GaAs. V.V.Chaldyshev, N.A.Bert, Y.G.Musikhin, A.A.Suvorova, V.V.Preobrazhenskii, M.A.Putyato, B.R.Semyagin, P.Werner, U.Gösele: Applied Physics Letters, 2001, 79[9], 1294-6

Figure 1

Effective As-Sb Interdiffusivity in GaAs