The comprehensive spectral study of lithium metagallate LiGaO2 crystal has been done including methods of pump-probe techniques, optical absorption, photoluminescence, luminescence kinetics, thermoluminescence and polarised luminescence in broad temperature region. Luminescence spectrum of the crystal contains the main emission bands at 4.43, 3.76, 2.38 and 1.77 eV. The novel data on luminescence excitation spectra including VUV area, kinetics and polarization are presented. The correlation between pump-probe experiment results and luminescence properties is found. Conclusions are done about the recombination character of all the observed emission bands, implying tunnel recombi-nation of donor-acceptor pairs.

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The investigation is devoted to the influence of different surrounding gases on the defect-related luminescence in hexagonal boron nitride (hBN). The photoluminescence spectra of hBN powder were measured for an hBN sample placed in different surroundings formed by ambient air, vacuum, as well as oxygen, nitrogen and argon gases. It was found that the 400 nm luminescence caused by native defects in hBN is sensitive to the oxygen gas and ambient air. Presence of oxygen gas around hBN considerably reduces the intensity of this luminescence. The results evidence that hBN powder can successfully be applied as the material for oxygen sensors.

We performed the studies of optical, photoelectric, and transport properties of a hydrothermal bulk n-type ZnO crystal by using the contactless optical techniques: photoluminescence, light-induced transient grating, and differential reflectivity. Optical studies revealed bound exciton and defect-related transitions between the donor states (at ∼60 meV and ∼240 meV below the conduction band) and the deep acceptor states (at 0.52 eV above the valence band). The acceptor state was ascribed to VZn, and its thermal activation energy of 0.43 eV was determined. A low value of carrier diffusion coefficient (∼0.1 cm2/s) at low excitations and temperatures up to 800 K was attributed to impact the recharged deep acceptors. Electron and hole mobilities of 140 and ∼80 cm2/Vs, correspondently, were determined at room temperature. The decrease of carrier lifetime with excitation was ascribed to increasing rate of radiative recombination at low temperatures and nonradiative recombination above the room temperature.