The diffusion of D in epitaxial layers of 4H-type material, with buried and highly Al acceptor-doped regions, was studied by means of secondary ion mass spectrometry. The D was introduced into the near-surface region by means of 20keV implantation, followed by thermal annealing. Anomalous accumulation of D in the highly doped layers was observed. In order to explain the accumulation kinetics, a model was proposed in which positively charged D ions were driven into the highly doped layer and became trapped there by the strong electric field at the edges. This effect was expected to be important for other semiconductors, since H was a common impurity that was often present at high concentrations.

Electric-Field Assisted Migration and Accumulation of Hydrogen in Silicon Carbide M.S.Janson, A.Hallén, M.K.Linnarsson, B.G.Svensson, N.Nordell, S.Karlsson: Physical Review B, 2000, 61[11], 7195-8