Vacancy-hydrogen defects in silicon studied by Raman spectroscopy

Abstract

A Raman study of hydrogen stretching modes in vacancy-hydrogen defects $({\mathrm{VH}}_{n},$ $n=1,2,3,4)$ is presented. The positions of the vibrational modes are compared to recent IR absorption results. The Raman lines exhibit pronounced polarization due to the $〈111〉$ orientation of the silicon-hydrogen bond. Based on the defect symmetry derived from the polarization-dependent Raman signals and the Raman intensities we assign the Raman lines to the defects ${\mathrm{VH}}_{4}$: 2234 ${\mathrm{cm}}^{\ensuremath{-}1}$${(A}_{1}$ mode), 2205 ${\mathrm{cm}}^{\ensuremath{-}1}$ ${(T}_{2}$ mode); ${\mathrm{V}}_{2}{\mathrm{H}}_{6}$: 2180 ${\mathrm{cm}}^{\ensuremath{-}1}$ ${(A}_{1g}$ mode), 2155 ${\mathrm{cm}}^{\ensuremath{-}1}$ ${(E}_{g}$ mode). We tentatively attribute the 2120- and 2099-${\mathrm{cm}}^{\ensuremath{-}1}$ lines to ${\mathrm{VH}}_{2}$ and the 2022-${\mathrm{cm}}^{\ensuremath{-}1}$ line to VH.