Hydrogen bonding in silicon-hydrogen alloys

Abstract

Infra-red and Raman spectra have been obtained from thin films of silicon-hydrogen and silicon-hydrogen-deuterium alloys deposited from low pressure, r.f. excited plasmas in mixtures of SiH₄/Ar and SiH₄/D₂/Ar respectively. The spectra are analysed using a valence-force-field model based on effective force constants determined from SiH₄. For alloys deposited onto substrates held at 25°C it is concluded that the structure is best described as a pseudobinary alloy of the form (Si)x(Si₂H₄)₁_ _x . In contrast, for material deposited on to a substrate at a temperature T _s⩾250°C, the hydrogen is incorporated onto Si-sites containing predominantlv one H-atom.