Thermoreflectance spectra of high-resistive CdS single crystals were measured in the region 108 to 320 "K. The main features of the spectra can be explained on the basis of simple models derived from existing theories. The genesis of the spectra shows that the excitonic transitions determine the thermoreflectance structure even at room temperature. B o 6 n a c~~ 108

Thermoreflectance of CdB near the Fundamental AbsorDtion Edge BY M. ILIEV, I. AMENOV, andS. STOYANOV The temperature-modulated spectra of absorption and reflectance in Cd9 were measured at room temperature by Berglund ( l ) and Lange and Henrion (2). However, because of thermal broadening the structure near the fundamental absorption edge cannot be definitely resolved. Thus, it is of considerable interest to study temperature-modulated spectra at low temperatures. In the present paper we report the results of thermoreflectance studies for CdS single crystals at low temperature.In this case the thermal broadening is so reduced and the peak height so increased that the peaks which appear near the fundamental absorption edge can be eaeily identified with the excitonic transitions.