Studies of silicon dihydride and its potential role in light-induced metastability in hydrogenated amorphous silicon

Recent nuclear magnetic resonance experiments on protons in hydrogenated amorphous silicon (a-Si: H) by T. Su, P. C. Taylor, G. Ganguly, and D. E. Carlson [Phys. Rev. Lett. 89, 015502 (2002)] have shown that light exposure leads to structures involving two protons separated by 2.3 +/- 0.2 angstrom. In this report, using supercell models of a-Si: H, we show that SiH2 configurations in the solid state are consistent with these observations. We find an average proton distance of 2.39 angstrom for SiH2 structures considered for four different configurations. We also find that the details of basis set and density functional are important for accurately representing these structures. (c) 2005 American Institute of Physics.