The diffusion of Be during the liquid-phase epitaxial growth of p-type (Al0.8Ga0.2)As layers on n-type GaAs substrates of (100) orientation was studied. The diffusion coefficients were deduced from the profiles of the free-carrier concentrations in the p-type GaAs region. At 700 to 900C, the results could be described by:

D (cm2/s) = 6.6 x 10-1 exp[-2.43(eV)/kT]

When the surface free-carrier concentration was greater than about 6 x 1018/cm3, an anomalous behavior was observed and the diffusivity could no longer be described by a constant diffusion coefficient.

K.Masu, M.Konagai, K.Takahashi: Journal of Applied Physics, 1983, 54[3], 1574-8