Luminescence behavior of a metallized semiconductor powder

Abstract

A version of the dead-layer model, originally developed for single crystals, is derived to describe the luminescence behavior of a metallized Zn(Cd)S:Ag phosphor powder. Electron-hole separation occurs only with excitation events capable of leading to free photoelectrons. The potential for the electrons in the deposited ‘‘metal’’ layer may deviate from the metal work function, when chemical modification, e.g., oxidation, of the metal occurs subsequent to deposition. We call particular attention to the dramatic difference in photoluminescence lifetime in the Zn(Cd)S under laser exposure conditions compared with lower intensity xenon flash exposure. Both this observation and the incomplete quenching are rationalized in terms of a double minimum potential surface for hole trapping at the Ag(I) centers.