Polarization Characteristics of the Red Luminescence in ZnS:Cu, In Crystals

Abstract

The polarization characteristics of the red-Cu, In luminescence in a meltgrown ZnS:Cu, In crystal with nearly cubic structure were investigated. The polarization with a particular azimuthal dependence is observed when excited by polarized light belonging to the excitation band characteristic of the center, indicating that the center has its own symmetry. In the polarization spectrum, the degree of polarization takes positive values at the long and short wavelength sides, while negative values in the middle, of the excitation band. The assumption is made that the luminescence transition takes place, within the center of C_s symmetry formed by the association of copper and indium ions at the nearest cation sites, from the indium level to the copper level. On the basis of the calculations on the energies of the split copper 3d-orbits, the luminescence transition is determined to be A″→A′, and the behavior of the polarization spectrum is reasonably interpreted.