Thermal decay of acoustic phonons and its effect in the 2LO mode on resonant Raman spectra of CdTe

Abstract

In this work, we show that the superposition of transverse acoustic (TA) harmonic phonons in the longitudinal optical overtone (2LO) phonon of the resonant Raman spectrum of CdTe is considerably reduced by slightly cooling the substrate. This effect not only modifies the line shape of the resonant Raman spectrum around the 2LO mode, but also significantly reduces the relative intensity of the line shape. A detailed spectral analysis allowed us to identify three contributions: a decaying exponential function due to TA harmonics, a component due to LO phonon overtones, and a component due to multi-phonon around the 2LO mode. The agreement between the experimental data and the simulations was good. Furthermore, a mathematical expression for the intensity of 2LO in terms of temperature is reported for the first time to our knowledge. The results reported here contributes to the understanding of the vibrational properties of CdTe.