Thermo‐absorption of CdS and CdSe in the exciton absorption region

Abstract

The thermal modulation method has been frequently applied to the study of the optical properties of solids (see e. g. (1)). In the present note measurements of the thermo-absorption of very thin CdS and CdSe single crystals are reported in order to find out which information can be gained from this type of spectra in comparison with dtz/do spectra.shaped with an area of 2x3 mm and a thickness of (3 to ~) x I O -~ cm. The crystals were mounted in a Dewar vessel and cooled to liquid nitrogen. Heating of the samples was performed either by directly passing a current through the sample between evaporated electrodes or by indirect heating placing the crystal between mica sheets covered with Sn02. The pulses applied to the sample had a frequency of 10 Hz. The temperature of the various samples was in the range around 90 K, as determined from the energetic position of the exciton lines, using the results of