The migration of thin highly p-doped layers in single and double heterostructures, grown using metalorganic vapor-phase epitaxy, was studied using capacitance-voltage etch profiling and secondary ion mass spectrometry. It was deduced that the diffusivity of Zn in Ga0.7Al0.3As could be described by:

D (cm2/s) = 1.5 x 10-3 exp[-2.2(eV)/kT]

for rapid thermal annealing. A model which was based upon an interstitial cum substitutional diffusion mechanism, with certain kinetic limitations, was successfully used to simulate the observed dopant concentration profiles. Markedly anomalous diffusion of Zn, from GaAs and into highly n-doped GaAlAs, was found.

N.Nordell, P.Ojala, W.H.Van, G.Landgren, M.K.Linnarsson: Journal of Applied Physics, 1990, 67[2], 778-86