Hydrogen Bonding in Hydrogenated Amorphous Germanium

Thin films of hydrogenated amorphous germanium (a-Ge:H) were prepared by radio frequency glow discharge deposition at various substrate temperatures. The hydrogen distribution and bonding struc-ture in a-Ge:H were discussed based on infrared absorption data. The correlation between infrared absorp-tion spectra and hydrogen effusion measurements was used to determine the proportionality constant for each vibration mode of the Ge-H bonds. The results reveal that the bending mode appearing at 835 cm1 is associated with the Ge-H2 (dihydride) groups on the internal surfaces of voids. While 1880 cm1 is assigned to vibrations of Ge-H (monohydride) groups in the bulk, the 2000 cm1 stretching mode is attributed to Ge-H and Ge-H2 bonds located on the surfaces of voids. For films associated with bending modes in the infrared spectra, the proportionality constant values of the stretching modes near 1880 and 2000 cm1 are found to be lower than those of films which had no corresponding bending modes.