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

D (cm2/s) = 6.5 x 10-5 exp[-1.8(eV)/kT]

for rapid thermal annealing, while the diffusivity could be described by:

D (cm2/s) = 1.9 x 10-7 exp[-1.5(eV)/kT]

for furnace 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.

Diffusion of Zn and Mg in AlGaAs/GaAs Structures Grown by Metalorganic Vapor-Phase Epitaxy. N.Nordell, P.Ojala, W.H.Van Berlo, G.Landgren, M.K.Linnarsson: Journal of Applied Physics, 1990, 67[2], 778-86