It was shown that the exponential depth profiles which were sometimes observed during H diffusion into semiconductors, such as Si and GaAs, could be explained by including a term (in the diffusion equation) that described the multiple trapping of H at an impurity. It was shown that the effective dimensionality of the random walk in the present case was infinite.

D.A.Tulchinsky, J.W.Corbett, J.T.Borenstein, S.J.Pearton: Physical Review B, 1990, 42[18], 11881-3