Open AccessДефекты и некоторые физические свойства номинально чистых и легированных цинком кристаллов ниобата лития
Author(s) -
Н.А. Теплякова,
М.В. Смирнов,
Н.В. Сидоров,
М.Н. Палатников
Publication year - 2021
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2021.08.51167.036
Subject(s) - luminescence , photoluminescence , valence (chemistry) , acceptor , materials science , zinc , doping , analytical chemistry (journal) , band gap , crystal (programming language) , niobium , chemistry , optoelectronics , condensed matter physics , physics , organic chemistry , chromatography , computer science , metallurgy , programming language
The features of defect structure and their influence on the properties of LiNbO3:Zn crystals, doped in a wide concentration range, including two concentration thresholds (at ~ 3.0 and ~ 6.8 mol. % ZnO in the melt), were studied by absorption IR spectroscopy in the region of OH--group valence vibrations, photoluminescence in the visible region of the spectrum, and photoinduced light scattering. In LiNbO3:Zn(0.004-2.01 mol. % ZnO) crystals the increase of zinc concentration led to increasing in the OH--group concentration and decreasing the luminescence intensity of luminescence centers associated with NbLi defects. Apparently, the latter was connected with the formation of small energy levels near the bottom of the conduction band as the zinc atoms displaced niobium atoms from the lithium positions in the ideal structure and the NbLi defect concentration decreased, respectively. In highly doped LiNbO3:Zn crystals (4.46-6.5 mol. % ZnO) and in the LiNbO3stoich(6.0 wt. % K2O) crystal there were lower OH--group concentration, the increase of band gap by 0.3-0.4 eV, and the increase of luminescence intensity in the green region of the spectrum due to the formation of new recombination channels compared to weakly doped crystals. In addition, in such crystals, the increase of proton conductivity was observed due to increasing in the concentration of interstitial hydrogen H+ and, as a result, the formation of many small acceptor levels near the valence band.