Synthesis and photoluminescence of gallium oxide ultra-long nanowires and thin nanosheets

β-Ga2O3 long nanowires and thin nanosheets have been successfully synthesized on a large scale through simple thermal evaporation of Ga/Ga2O3 mixture powders in the presence of Au catalyst. The as-synthesized products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), room-temperature photoluminescence (PL) and optical absorbance. The diameters and lengths of Ga2O3 nanowires range from 30-50nm and 60-80 μm in lengths. The nanosheets have thickness of 10-20 nm and lengths up to 20 μm. The SAED and HRTEM observations suggest that both nanowires and nanosheets are single crystalline and free from defects. However, different interplanar spacings were observed for nanowires and nanosheets, indicating the different growth pattern of these two structures. The PL spectrum of β-Ga2O3 nanostructures exhibits a broad, strong blue emission band centered at 465 nm. The optical absorption spectrum shows intensive absorption feature in the UV spectral region. The possible growth mechanism of β-Ga2O3 nanostructures was also discussed.