Optical properties and defect study of Ca~(2+) co-doping Lu_2Si_2O_7: Ce~(3+) single crystal scintillator

摘要

Single crystal of Lu_2Si_2O_7 (LPS): 0.5%Ce, 0.1%Ca was grown by the Czochralski method. The X-ray excited luminescence (XEL), photoluminescence excitation (PLE), photoluminescence (PL) and transmittance spectra were measured and discussed. The as grown LPS: Ce, Ca sample presents excellent optical quality with 81% transmittance. Two absorption peaks locate at 300 and 350 nm, corresponding to the electron transition of Ce~(3+) from 4f ground to 5d_1 and 5d_2 respectively. According to the Gaussian fitting, the XEL curve of LPS: Ce, Ca can be fitted into two peaks centering at 378 and 407 nm respectively. It is found that the addition of Ca~(2+) in LPS: Ce introduces more oxygen vacancies, leading to the decreases of the luminescence efficiency of LPS: Ce. Through the thermally stimulated luminescence (TSL) measurement, two kinds of charge trap are found in LPS: Ce, Ca, whose energy depths are 1.20 and 1.47 eV. The trap at 1.20 eV is intrinsic electron trap induced by Ce~(3+) doping in LPS host and the other trap is formed by the both impact of (V_o)~·· and Ca_(Lu)~× defects.