Long Wavelength Bound Exciton Emission in CdS

Publisher Website
Google Scholar
Abstract
Our investigations of CdS single crystals at low temperatures (~5 K) have uncovered a series of sharp luminescent lines in the wavelength region 5050 to 5150 Å, including two transitions originally reported by Reynolds and Litton. Excitation spectra of these long wavelength lines have enabled us to find a close relationship between the various transitions. We believe that they result from the radiative decay of two distinct bound exciton complexes, which we have labeled I6 and I7, in the notation of Reynolds and Litton. These complexes are probably formed from excitons bound to deep impurities in CdS. Results of the excitation spectra have also suggested the presence of a resonance exciton transfer mechanism from the I2 complex (exciton bound to a shallow neutral donor) to the more strongly bound state represented by the I6 complex. We have investigated the effects of variations in excitation intensity and sample temperature on the long wavelength lines, and have measured a thermal activation energy of 43.2 ± 0.2 meV for I6a, a transition of the I6 complex. On the basis of our experimental results we have constructed a tentative energy level diagram for decay of the I6 bound exciton.

This publication has 0 references indexed in Scilit: