The absorption lineshapes which were associated with the stretching-mode of bond-center H (HBC+) at 1794/cm, and the 2-fold degenerate mode of H near to the tetrahedral site (H-) at 745/cm were measured using infra-red absorption spectroscopy. The HBC+ lineshape measured at 10K, at low H concentrations, yielded a lifetime of between 15 and 23ps. This was similar in magnitude to the 7.8ps observed for the same defect in Si, and indicated that the lifetime of the bond-centered mode was largely insensitive to the phonon frequency distribution of the host material. Pure de-phasing dynamics of H in Ge were studied by measuring the shapes of the 1794 and 745/cm lines as a function of temperature. The measurements were analyzed by using a new exchange model for vibrational de-phasing. The temperature dependence of the 1794/cm lineshape was attributed to thermal fluctuations in the occupation number of a pseudo-localized mode at 75/cm.

Vibrational Dynamics of Isolated Hydrogen in Germanium. C.P.Cheney, M.Budde, G.Lüpke, L.C.Feldman, N.H.Tolk: Physical Review B, 2002, 65[3], 035214 (9pp)