HIGH-PRESSURE THERMOLUMINESCENCE AND PHOTOLUMINESCENCE STUDY OF ZNS-MN-CU-CL PHOSPHOR

The effect of pressure has been studied on the thermoluminescence and photoluminescence of a well-characterized sample of ZnS:Mn:Cu:Cl. The thermoluminescence was particularly revealing. Initially two traps were present. As they increased in depth with increasing pressure new shallower traps appeared. The pressure dependence of four traps was established. By comparison with pressure measurements on ZnS doped only with Mn+2 and only with Cu+ and Cl-, we established that the deepest trap is associated with defects introduced by Mn+2, while the two traps next lower in energy are associated with defects introduced by Cl-. The shallowest trap could not be assigned to a specific defect. The photoluminescence emission (from the 4T1, to the 6A1 energy level of Mn+2) shifted to lower energy at a rate identical to that previously reported for a less well-characterized ZnS:Mn sample. The shift could be described quantitatively in terms of changes in the ligand field parameters.