Spectral Analysis of Luminescence of High Density Excitons in CdS

Abstract

A spectral analysis of luminescence of high density excitons in CdS in the 4.2–77 K temperature range is performed by the use of theoretical curves for the M, P n=2 , P n=∞ , E and A-LO lines. The curve given by a suitable sum of calculated curves reproduces the observed spectrum quite well. Thus the dependence of these luminescence lines on temperature is interpreted quantitatively. With increasing temperature from 4.2 K, the M line decreases gradually, becoming very weak at 77 K due to thermal dissociation. The P n=∞ line grows with temperature, becoming stronger than the P n=2 line at 77 K. Simultaneously the E line grows in a similar manner to the P n=∞ line. This is ascribed to the increased number of free electrons brought about by the enhancement of the P n=∞ process. The phenomenon, observed previously, that the high density exciton system becomes hot at 1.8 K is not observed at higher temperature.