Nanooptics and photonics
Microstructure and properties of -Ga2O3 ceramics
Luchechko A.1, Vasyltsiv V.1, Shpotyuk Ya.1,2, Kostyk L.1, Kushlyk M.1, Slobodzhan D.1 , V. Hreb3, Vasylechko L.3, J. Cebulski2
1Department of Sensor and Semiconductor Electronics, Ivan Franko National University of Lviv, Tarnavskogo Str., 107, Lviv 79017, Ukraine
E-mail: andriy.luchechko@lnu.edu.ua
2Institute of Materials Engineering, University of Rzeszow, Rzeszow, 35-959, Poland

3Lviv Polytechnic National University, Lviv, S. Bandera St., 12, 79013, Ukraine

The growing need for energy-saving devices motivates researchers to explore new materials and optimize existing ones. Gallium oxide is a promising material with semiconductor properties for application as an efficient phosphor emitting in UV and visible spectral regions [1]. Modification of -Ga2O3 by doping with different metal ions and/or annealing in the oxidizing and reducing atmospheres allows for controlling the structural, electrical, and spectral characteristics.
In this work, -Ga2O3 ceramic samples have been synthesized via a solid-state reaction method at 1200°C. The samples were characterized using XRD analysis, electron microscopy, optical and luminescence spectroscopy as well as the measurement of electrical characteristics.
Rietveld's refinement of β-Ga2O3 ceramics confirms that samples are stabilized in monoclinic symmetry with C2/m space group. In this ceramic, the main peak of luminescence excitation is observed in the region of the absorption edge (260 nm) and the low-intensity peak is in the region of transparency with a maximum near 370 nm. The emission spectrum shows three host emission peaks located at 380, 420, and 480 nm with different relative intensities under these excitation wavelengths. Photoluminescence of ceramics at room temperature is mainly due to the recombination of electrons and holes through donor-acceptor pairs. Such ceramics has promising applications in devices of power electronics and UV-optoelectronics. The influence of annealing in a vacuum on structural, electrical, and luminescent properties, as well as on the morphology of the surface of β-Ga2O3 ceramics is discussed.

1.	Guo, D., et al. "Review of Ga2O3-based optoelectronic devices." Materials Today Physics 11 (2019) 100157.