Oxygen-bonding environments in glow-discharge-deposited amorphous silicon-hydrogen alloy films

Abstract

This paper presents the results of a systematic study of oxygen incorporation in $a\ensuremath{-}\mathrm{Si}:\mathrm{H}$ alloys produced by the glow-discharge decomposition of Si${\mathrm{H}}_{4}$, ${\mathrm{H}}_{2}$, and ${\mathrm{O}}_{2}$. We identify four oxygen-related absorption bands, at 2090, 980, 780, 500 ${\mathrm{cm}}^{\ensuremath{-}1}$, and show that the absorption strength in each band scales linearly with the oxygen concentration. We demonstrate that oxygen can increase the solubility of hydrogen in $a\ensuremath{-}\mathrm{Si}$ in the monohydride bonding geometry. The features identified above are shown to be characteristic of a bonding site in which the oxygen and hydrogen atoms are bonded to the same silicon atom. We find no features in the infrared absorption that are associated with bonding configurations having OH groups. In films containing both oxygen and polysilane bonding, as evidenced by the doublet absorption at 845 and 890 ${\mathrm{cm}}^{\ensuremath{-}1}$, we find no evidence for bonding sites in which a substantial fraction of the silicon atoms have one oxygen and two hydrogen neighbors.