The theoretical cluster-Bethe-lattice method was used here to investigate the shallow defect states in hydrogenated amorphous silicon oxide. The electronic density of states for the SiO2 Bethe lattice of various Si–O–Si angles, non-bridging O Si–O., peroxyl radical Si–O–O., threefold coordinated O3 and Si–H bonds were calculated. The variation of the Si–O–Si bond angle caused the band-gap fluctuation and induced tail states near to the conduction-band minimum. The Si–O. and Si–O–O. bonds introduced shallow defect states in the energy gap near to the top of the valence band. The Si–H bond induces a defect state, in the energy gap near to the conduction band minimum, in a-SiOx with high O concentration, but not low O concentration. The O3 bond itself does not induce defect state in the energy gap. The O3+D- complex, formed by the O3 and threefold coordinated Si, induces shallow state in the energy gap near to the conduction band minimum. This defect state could explain the energy shift of photoluminescence during annealing.

Shallow Defect States in Hydrogenated Amorphous Silicon Oxide. S.Y.Lin: Computational Materials Science, 2002, 23[1-4], 80-4