Ultraviolet photoluminescence of β-Ga2O3 microparticles synthesized by hydrothermal method

The monoclinic beta-Ga2O3 samples were prepared by the hydrothermal method. Production of phase pure beta-Ga2O3 products with high crystallinity was demonstrated by X-ray diffraction analysis. Scanning electron microscope images revealed that the beta-Ga2O3 microparticles are spindle shaped with layered sheet structures. Many nanopores are present on the surfaces of the beta-Ga2O3 samples, which are formed by dehydroxylation of the GaOOH precursor by the two-phase transition that occurs during the calcining process. The Raman spectrum of beta-Ga2O3 samples showed 11 active vibrational peaks, including the vibrational and translational modes of the GaO4-GaO6 chain, the regular octahedral GaO6-bending vibration mode, and the regular tetrahedral GaO4 stretching, as well as the bending vibration mode. Infrared spectroscopy showed a peak at 466.7 cm(-1), corresponding to the Ga-O bond contraction vibration in the GaO6 regular octahedron, and a peak at 674.9 cm(-1), corresponding to the shrinkage vibration of the Ga-O bond in the GaO4 regular tetrahedron. The ultraviolet emission peak at 398 nm in the photoluminescent spectrum is excited by the recombination of the donor formed by the oxygen vacancy and the acceptor formed by the gallium vacancy or gallium-oxygen vacancy pair. A weak ultraviolet emission peak is also observed at 275 nm. The growth mechanism of the beta-Ga2O3 products was carefully analyzed and found to be mainly controlled by the Ostwald ripening mechanism.

Automated summary

Monoclinic beta-Ga2O3 samples with high crystallinity were prepared using the hydrothermal method. The presence of nanopores on the sample surfaces, formed by the dehydroxylation of the GaOOH precursor during the calcination process, was observed. Various vibrational modes of GaO bonds were identified in the Raman spectrum of beta-Ga2O3 samples. The photoluminescent spectrum showed the recombination of defects, including oxygen vacancy donors and gallium vacancy or gallium-oxygen vacancy acceptors.