The locally restricted motion of H and D atoms which were trapped at Cd acceptors was studied by using perturbed angular correlation spectroscopy. Close Cd-H and Cd-D pairs were identified via their characteristic electric field gradients. The kinetics of these complexes were deduced directly from the time spectra. At temperatures of between 270 and 430K, clear evidence was found for the thermally activated motion of H or D about Cd; with an activation energy of 0.21eV for both H and D. The isotopic mass-dependent attempt frequencies were of the order of 109/s. The ratio of the frequency for H, as compared with that for D, was 3.3.

Direct Evidence for Localized Motion of Hydrogen in Cd-H Complexes in Silicon. M.Gebhard, B.Vogt, W.Witthuhn: Physical Review Letters, 1991, 67[7], 847-50