Luminescence properties of LiGaO 2 crystal

Abstract

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.

Comparison of Luminescence in LiGaO2, Al2O3-Ga and Al2O3-Li Crystals

“…The main luminescence bands of LGO at 280 (4.43 eV) and 330 nm ( Fig. 1) have already been studied in [3]. The 280 nm band is excited in the spectral range, corresponding to the exciton states (a sharp feature at 6 eV) and band-to-band transitions.…”

“…The presence of the 280 nm band in XL afterglow and TL emission spectrum gave an additional argument for the recombination nature of this luminescence band. LGO crystal optical absorption at RT (1) [1,3], PL at laser excitation 193 nm (2) and 248 nm (3); PLE of 280 nm emission (4) and 330 nm emission (5).…”

“…The 280 nm band is excited in the spectral range, corresponding to the exciton states (a sharp feature at 6 eV) and band-to-band transitions. Based on the luminescence features such as superposition of exponents in the luminescence decay pulses (similar to luminescence properties in Ga 2 O 3 crystal [9]), blue shift of the emission band and decrease of thermal quenching rate with an increase of the excitation light intensity, it has been proven that this emission results mainly from tunnel recombination of donor-acceptor pairs (DAP) with the random distribution of separation distance [3]. In the present study, we have got the additional confirmation of the recombination character of this emission -the 280 nm emission band has been observed in X-ray induced processes: XL afterglow and TL emission spectra at temperatures below 80 K. Presence of the DAP recombination with participation of the crystal host components means that the irradiation-produced charge carriers -electrons and holes -are self-trapped on the regular lattice sites.…”

“…Recently we have studied luminescence properties of the wide band gap crystal lithium metagallate LiGaO 2 (LGO) (optical gap around 6 eV [1]) grown by authors of [2] and found out that the main emission bands are located at 280 and 330 nm, (4.43 and 3.76 eV), correspondingly, see Fig.1. [3]. The 280 nm band is excited only in the range of intrinsic absorption including the exciton-like sharp band at ~6 eV (206 nm), while the 340 nm band is also excited within optical transparency range peaking at 220 nm.…”

“…The 280 nm band is excited only in the range of intrinsic absorption including the exciton-like sharp band at ~6 eV (206 nm), while the 340 nm band is also excited within optical transparency range peaking at 220 nm. The 280 nm band was assigned to recombination luminescence of randomly separated donor-acceptor pairs (DAPs); the 340 nm band also demonstrated recombination character [3]. However, the components of the donoracceptor pairs remained unknown.…”