De-Excitation of ZnS and ZnCdS Phosphors by Electric Fields

Abstract

With the aid of ac impedance measurements, the influence of strong ac and dc fields applied during the decay of photoconductivity of ZnS and ZnCdS phosphors is described. Rise and decay curves of photoconductivity with and without additional field application are presented which demonstrate that electric fields accelerate the de-excitation process. Ac fields are capable of removing all excited electrons from the pre-excited ZnS ($\mathrm{LG}$) phosphor and dc fields show a similar but weaker effect. This de-excitation is attributed to the considerable reduction of retrapping of excited electrons when these phosphors decay under the action of electric fields.