Determination of depths and frequency factors of traps by UV amplitude modulated excitation

Abstract A study is made of the photoluminescence of ZnS-type phosphors submitted to a UV excitation modulated at various frequencies. The resulting emission shows a modulation rate and a phase shift which are functions of the occupancy of the various groups of traps, and therefore depend on temperature. Starting from the phase shift, the activation energy as well as the frequency factor of various trapping levels in ZnS/Cu and CdS, ZnS/Mn, Au samples have been computed. These results are compared with those deduced from ordinary or fractional glow curves. The advantage of the present modulated excitation method is to yield simultaneously both the activation energy and the frequency factor.