[Simultaneous determination of rate ratio of recombination to capture and trap depth from thermo-luminescence of ZnS:Cu, Co].
The recombination luminescence is in nature a bimolecular process but, the decay rule may be changing from that of mono-molecular to bimolecular rule, i.e., from exponential to hyperbolic rule, depending on the behavior of conduction electrons. This behavior is represented by relative rate of recombination with ionized centers to that of capture by traps. This relative rate depends partly on the intrinsic parameters of the specified materials, and partly on the concentration of conduction electrons supplied by traps. Each point of the TL curve is related to the material parameters and the release of electrons from traps. The ratio of relative rate of recombination to that of capture gamma(epsilon) = sigma0(n0)/sigma(nu - n) involves the parameter epsilon. They are inseparable and must be determined at the same time. In the present report, starting from the same sample ZnS:Cu, Co which has only one peak in its TL(i. e., only one kind of luminescent center and only one kind of traps), and the experimental value of sigma/sigma0 = 0.005, the authors use thermo-luminescence kinetics models and some mathematic tools to exactly estimate the ratio sigma0(n0)/sigma(nu) and the trap depth epsilon simultaneously from the glow curve. The authors found that sigma0(n0)/sigma(nu) = -2.6 and epsilon = 0.86 eV.
Wang
Li-wei
LW
Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044, China.
Xu
Zheng
Z
Teng
Feng
F
Zhang
Fu-jun
FJ
Meng
Li-jian
LJ
Xu
Xu-rong
XR
D003035:Cobalt / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods*; D013440:Sulfides / Q000032:analysis*; D013696:Temperature; D017967:Zinc Compounds / Q000032:analysis*
D013440:Sulfides; D017967:Zinc Compounds; D003035:Cobalt; D003300:Copper; C031238:zinc sulfide