Ultrafast excitation and de-excitation of the SiH stretching mode in a-Si:H

Abstract

We report the first direct measurement of the energy relaxation of the SiH and SiH 2 stretching modes in hydrogenated amorphous silicon obtained by the equal-wavelength room-temperature pump-probe technique using a free electron laser. The recovery of the transient bleaching can be fitted with a bi-exponential function, with relaxation times of ∼ 20 ps and ∼ 100 ps and ∼ 13 ps and ∼ 50 ps for SiH and SiH 2, respectively. We propose an explanation based on phonon-phonon interactions.