Radiation-Induced Changes of the Photoluminescence Spectra of Cadmium Sulfide
Radiation-induced changes in the photoluminescence spectra of cadmium sulfide have been measured over a wavelength range from 4800 to 5400 A. Gamma-ray induced changes in the 4.2°K photoluminescence spectra show a reduction in intensity of bound exciton transitions I1 and I5 and edge emission in contrast to an enhancement of a spectral line at 4867.2 A (which we designate as IR). These changes were measured for irradiation temperatures of 300°, 78°, and 4.2°K. The 78°K photoluminescence shows that exciton emission is more sensitive to radiation-induced changes than is edge emission. Thermal annealing takes place below room temperature, particularly in the 140° to 260°K region. The sensitivity of the luminescence intensity to radiation exposure only at cryogenic temperature anid the thermal annealing of the radiation-induced changes are attributed to the mobility of defects at and below room temperature. Studies of polarized luminescence and the temperature dependence of the luminescence show that IR is like the I2; exciton lines. Optical quenching at 4.2°K indicates that the defect responsible for IR is sensitive to its charge state. The results of electron exposures at various energies at approximately 90°K show that IR is associated with a sulfur defect, possibly SI