Weakly bound carbon-hydrogen complex in silicon

Local vibrational modes of a weakly bound carbon-hydrogen complex in silico n have been identified with infrared-absorption spectroscopy. After implant ation of protons at similar to 20 K and subsequent annealing at 180 K, two carbon modes at 596 and 661 cm(-1), and one hydrogen mode at 1885 cm(-1) ar e observed. The three modes originate from the same complex, which is ident ified as bond-centered hydrogen in the vicinity of a nearby substitutional carbon atom. Ab initio theory has been applied to calculate the structure a nd local modes of carbon-hydrogen complexes with hydrogen located at the fi rst, second, and third nearest bond-center site to substitutional carbon. T he results support our assignment.