Optical Properties and Defect Study of Ca<sup>2+</sup> Co-Doping Lu<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>:Ce<sup>3+</sup> Single Crystal Scintillator

Abstract

Single crystal of Lu2Si2O7 (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 Ce3+ from 4f ground to 5d1 and 5d2 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 Ca2+ 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 Ce3+ doping in LPS host and the other trap is formed by the both impact of and defects.