Photoexcited and photostimulated luminescence and conduction in zinc silicate single crystals with deep centers and traps

Abstract

Concurrent measurements of photoluminescence (PL) and photocurrent (PC) and photostimulated luminescence (PSL) and photostimulated current (PSC) at 77–400°K on crystalline zinc silicate:Mn +2 with and without arsenic provide direct evidence of the involvement of the conduction band in the phosphorescence (PP) process. The PL, peaked at 525nm, remains relatively constant over the temperature range whereas the PC, 10 2 to 10 3 times higher than dark current, exhibits a exp (-E/KT) dependence suggesting a trap influenced conduction process. Both PSL and PSC, strongly dependent on temperature, exhibit two peaks near 123 to 173°K and 313 to 333°K and a minimum near 233°K. The long term decay rate of PSL is somewhat temperature dependent, considerably reduced by the As doping and much faster than that of PSC. This requires theoretical interpretation involving several electron traps interacting with the Mn +2 center via the conduction band.