Intrinsic and defect-related luminescence of YAlO3 and LuAlO3 single crystals and films

Abstract

The work is dedicated to investigation of the luminescent properties of YAlO3 (YAP) and Lu0.95Y0.05AlO3 (LuYAP) crystals, grown from the melt by different crystallization methods. The intrinsic luminescent properties of YAP and LuYAP crystals were compared also with behavior of single crystalline films of these perovskites, grown using the liquid phase epitaxy method from the melt-solution based on the PbOB2O3 flux. The significant differences in the luminescent properties of YAP and LuYAP crystals were observed. These differences are explained by the various concentrations of the YAl and LuAl antisite defects (ADs) and oxygen vacancies formed during high-temperature crystallization of YAP and LuYAP crystals from the melt at the temperatures above 2000 °C. The ADs and oxygen vacancies form in YAP and LuYAP crystals the different types of emission centers in the UV and visible ranges. The luminescence of defect centers in the 4.1–6.2 eV range are related to the emission of exciton localized around and bound with the ADs as analogues of cations isoelectronic impurities. The emission centers of YAP and LuYAP crystals in the 2.75–4.1 eV range are formed by F+ and F centers. Apart from the intrinsic radiative transitions of F+ and F centers, the luminescence of excitons localized around F and F+ related centers in YAP and LuAP crystals is found as well. The emission bands of YAP and LuAP crystals in the visible range probably are caused by the aggregates of F+ and F centers.