It was noted that vacancy-type Frank dislocation loops, which were the cause of shallow etch-pit defects, dispersed during heat treatment via the out-diffusion of point defects. This created a defect-free denuded zone under the surface of a wafer. The activation enthalpy for diffusion of the Ga vacancy (which corresponded to formation of the denuded zone) was estimated to be 4.0eV.

Formation of a Defect-Free Denuded Zone in GaP Substrate by Thermal Annealing. H.Okada, S.Ohmoto, T.Kawanaka: Journal of Applied Physics, 2000, 88[11], 6943-4