Application of the reflection-absorption spectroscopy to the semiconductorthin films

The study of bulk phonons in thin films is limited due to the low energy of far-infrared sources. The infrared reflection-absorption spectroscopy (IRA S) technique has, therefore, been developed. In the case of incidence devia ting from normal two states of polarization of incident light should be tak en into consideration. The application of approximation of ultra thin films enables to obtain the simple relations Delta R\R-0 between the change of r eflectivity of a metal plate covered with a film and that of the metal subs trate. Delta R\R-0 has been obtained for two polarizations, namely: s and p . The present research has demonstrated that this method proved to be parti cularly usable for the multimode crystals where the oscillator strength is distributed on several modes. The IRAS technique has been applied to the Zn xCdyHg1-x-yTe (ZMCT) thin films. The frequencies of LO and TO phonons were determined by comparing the theoretical and experimental spectra. (C) 2000 Elsevier Science S.A. All rights reserved.