Absorption line shapes associated with the stretch mode of bond-center hydrogen (HBC (+)) at 1794 cm-1 and the twofold degenerate mode of hydrogen near the tetrahedral site (H(-)) at 745 cm-1 in germanium are measured with infrared-absorption spectroscopy. The HBC (+) line shape measured at 10 K for the case of low hydrogen concentrations gives a lifetime between 15 and 23 ps. Similar in magnitude to the 7.8±0.2 ps observed for the same defect in silicon [M. Budde et al, Phys. Rev. Lett. 85, 1452 (2000)], this observation indicates that the lifetime of the bond-centered mode is largely insensitive to the phonon frequency distributions of the host material. Pure dephasing dynamics of hydrogen in germanium are studied by measuring the shape of the 1794- and 745-cm-1 lines as a function of temperature. These measurements are analyzed using a recently formulated exchange model for vibrational dephasing. The temperature dependence of the 1794-cm-1 line shape is attributed to thermal fluctuations in the occupation number of a pseudolocalized mode at 75±2 cm-1.
|Number of pages||9|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jan 15 2002|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics