RESUMO
In the paper, five ZnS:Cu electroluminescent material specimens were prepared by adding 0.05%, 0.10%, 0.15%, 0.20% and 0.25% Cu+ to ZnS. From the sample's thermoluminescence curve and luminance, the authors can see that with the variation of Cu+ concentration, the peak of thermoluminescence curve changed correspondingly. At first with the increase of Cu+ concentration, the peak of thermoluminescence curve rised gradually. When the Cu+ concentration was 0.05%, the peak of thermoluminescence curve was 124.15 which attainded max, when the Cu+ concentration was 0.25%, the peak of the curve of thermoluminesence forther decreased to 51. But the temperature corresponding to the peak of the curves of thermoluminesence didn' change, which means that the depth of electron trap did not vary. The authors therefore conclude that excessive Cu+ results in a decline of luminance because the energy of trapped electrons turns into the transition without radiation, though the probability of trapping electrons increases and the life of photoelectrons shortens as the luminescence center increases. In this way, there is an optimal value for Cu+ concentration, which leads to the peak of the curves of thermoluminesence and the maximum of luminance.
RESUMO
The process of decay of photo-generated electrons in the conduction band of ZnO:Zn and ZnO powder materials after excitation with a ultra-short pulse laser has been investigated in this paper by microwave absorption method. The excitation and emission spectra of ZnO:Zn were measured at room temperature. It was measured that the lifetime o photoelectrons in the materials ZnOand ZnO:Zn are 64 ns and 336 ns respectively. It is believed that the increase of the lifetime in the material of ZnO:Zn is due to the prolong of relaxation time caused by the defect structure in the material.