Spatial diffusion of highly created excitons in CdS

Abstract

The exciton density is determined in CdS from the magnetic field dependence of the triplet-exciton emission intensity. The result shows that the exciton density is saturated markedly for very intense excitations by a nitrogen laser. This behavior is analyzed in terms of the diffusion process of optically created particles from the generated surface to the interior of the crystal. The diffusion length is found to be enhanced by two orders of magnitude for high excitations. This fast diffusion is ascribed to the high-density electron-hole plasma created at the crystal surface.