Особенности фотолюминесценции в кристаллах ниобата лития, легированных цинком в широком диапазоне концентраций

Abstract

The concentration changes in the photoluminescence spectra of LiNbO3 : Zn crystals (0.004 ÷ 6.5 mol.% ZnO) were studied. It was found that with the increase of zinc concentration from 0.004 to 1.42 mol.% ZnO, the intensity decrease of luminescence bands caused by VLI, NbNb, and NbNb−NbLi defects was observed. As the crystal composition approached the second concentration threshold (≈ 7.0 mol.% ZnO), the luminescent halo shifted by ≈ 0.41 eV to the high-energy region of the spectrum and the intensity of the luminescence centers increased at 2.66 and 2.26 eV. It was caused by the appearance of ZnLi point defects. It was shown that in the LiNbO3 : Zn(4.69 mol.% ZnO) crystal obtained by homogeneous doping technology, there is a greater number of luminescence centers of different origin than in congruent and zinc-doped crystals obtained by direct melt doping technology. In the LiNbO3 : Zn crystal (4.52 mol.% ZnO), the luminescence of the main defects (VLi, NbNb, ZnLi) was quenched by increasing the fraction of nonradiative transitions relative to other LiNbO3 : Zn crystals in the concentration range [ZnO] = 4.46 ÷ 6.50 mol.%.