Catalytic growth of Ga2O3 nanowires by physical evaporation and their photoluminescence properties

Gallium oxide (Ga2O3) nanowires were fabricated through simple physical evaporation in oxygen atmosphere using GaN powder as raw material and an Al2O3 substrate coated with a thin indium layer. The morphology and structure of the nanowires were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and Raman spectrum. These nanowires have diameters ranging from 20 to 60 nm and lengths ranging from several tens to several hundreds micrometers. Photoluminescence spectrum under excitation at 254 nm shows that these Ga2O3 nanowires have a blue emission at 436 nm and an ultraviolet emission at 330 nm, which may be attributed to the defects such as the oxygen vacancies and gallium-oxygen vacancy pairs