Raman spectra and structure of amorphous Si - art. no. 115210

In 1985, Beeman, Tsu, and Thorpe established an almost linear relation betw een the Raman transverse-optic (TO) peak width Gamma and the spread in mean bond angle Delta theta in a-Si. This relation is often used to estimate th e latter quantity in experiments. In the last decade, there has been signif icant progress in the computer generation of sample networks of amorphous s ilicon. Exploiting this progress, this paper presents a more accurate deter mination of the relation between Gamma and Delta theta using 1000-atom conf igurations. Also investigated and quantified are the relations between the TO peak frequency and the ratio of the intensities of the transverse-acoust ic (TA) and TO peaks, both as functions of Delta theta, As Delta theta decr eases, the TA/TO intensity ratio decreases and the TO peak frequency increa ses. These relations offer additional ways to obtain structural information on a-Si from Raman measurements.