The energetics of H in amorphous material were investigated by means of  ab initio  density-functional calculations. The situation of H at a Si bond-center site in amorphous material was compared with that of H in crystalline material. A transport level, shallow trap, and deep trap could be associated with Si-Si bond center sites, highly-strained Si-Si bonds, and isolated dangling bonds, respectively. The results also compared well with the observed behavior of amorphous hydrogenated Si, with regard to H evolution and long-range diffusion.

B.Tuttle, J.B.Adams: Physical Review B, 1998, 57[20], 12859-68