IR spectroscopy of a-Si 1 − xSn x: H films

Abstract

Several hydrogenated amorphous Si 1 − xSn x alloy films of thicknesses varying between 4000 and 8000 Å were prepared on impurity-free silicon substrates using a reactive co-sputtering technique. The tin concentration varied among different samples from 0% to 10.7% and was determined using Auger depth profiling. The oxygen contamination increased with the tin concentration but it was found to be uniform throughout the thickness of the films. Samples were characterized using secondary ion mass spectrometry to detect the presence of various molecular species. The IR measurements showed vibrational bands characteristics of Si-H, Sn-H, Si-O and perhaps Sn-O. The presence of tin is found to facilitate the formation of more Si-H than SiH 2 bonds. The Si-O band shifts to 1075 cm −1 from 1030 cm −1 as the tin concentration is increased to 0.1%. In addition, a new peak at 1155 cm −1 appears in the mixed samples with tin concentration over 10%.