Photoluminescence and absorption identification of Ti~(3+) in zinc telluride

摘要

Low-temperature photoluminescence (PL) and optical absorption are carried out on a Ti-doped ZnTe bulk crystal with carefully optimized experimental conditions. The influence of excitation energy in the PL is checked. Two zero-phonon lines (ZPLs) are clearly identified and phonon sidebands are evidenced in the PL and in the absorption, respectively. A relation is established between the PL and the absorption for the intensity ratio of the two ZPLs. Thereby, the Ti ion is identified as Ti~(3+) and the ZPLs in the PL spectrum are from the Γ_7 and Γ_8 levels of the ~2T_2 excited state to the well-separated Γ_8 level of the ~2E ground state. The separation of the two excited levels is 2.4 cm~(-1). The population numbers are shown to be fully thermalized in the ~2T_2 excited state in the PL process.