Luminescence characteristics of magnesium aluminate spinel crystals of different stoichiometry

Functional Materials and Nanotechnologies 2018

Prieditis, G.^1 ; Feldbach, E.^1 ; Kudryavtseva, I.^1 ; Popov, A.I.^2 ; Shablonin, E.^1 ; Lushchik, A.^1

Institute of Physics, University of Tartu, W. Ostwald 1, Tartu

50411, Estonia^1

Institute of Solid State Physics, University of Latvia, Kengaraga 8, Riga

LV-1063, Latvia^2

关键词: Anti-site defect;    Electronic excitation;    Electrons and holes;    Low temperatures;    Luminescence characteristics;    Magnesium aluminate spinel;    Structural defect;    Thermally stimulated luminescence;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/503/1/012021/pdf
DOI  :  10.1088/1757-899X/503/1/012021

来源: IOP

【 摘 要 】

Magnesium aluminate spinel single crystals with different stoichiometry, MgAl2O4 (1:1 spinel) and MgO 2.5Al2O3 (1:2.5) were investigated using different optical methods (cathode-, photo- and thermally stimulated luminescence (TSL), optical absorption, "creation spectra" of TSL peaks and phosphorescence by VUV radiation). Low-temperature charge carrier traps and the position of intrinsic UV emission bands depend on the degree of stoichiometry. Antisite defects (ADs), Mg2+ or Al3+ located in a "wrong" cation site (Mg|A1 or Al|Mg) are the main as-grown structural defects, which serve also as efficient traps for electrons and holes as well as seeds for bound excitons. AD concentration is especially high in 1:2.5 spinel. There are several manifestations of ADs (electronic excitations near ADs) in the spectral region of 7-7.5 eV, slightly below the energy gap.