Illumination- and Annealing-Induced Changes in the Infrared and Raman Spectra of a-Si:H

Abstract

ABSTRACTWe have investigated the changes, produced by light-soaking, in both the IR and Raman responses of the Si-Hn stretching peaks in the 2000-2100 cm−1 range. Our observations of the IR response are in qualitative agreement with those of Kong and co-workers [1]: that is, short-term light soaking produces an increase in the intensity of the signal and a simultaneous shift to lower frequency. In contrast, short-term light soaking decreases the total intensity of the Raman signal in the 2000-2100 cm−1 range, when normalized to the TO phonon peak at about 480 cm−1. In both cases, these modifications are reversed on annealing at 200° C. We suggest that these changes are attributable to alterations in the environments of the Si-Hn bonds, with the resultant transfer of intensity between IR and Raman matrix elements. Details of the evolution of the components of the Raman spectrum in the 2000-2100 cm−1 range are presented, and compared with IR changes in the same range.