Single crystalline β-Ga2O3 nanowires synthesized by thermal oxidation of GaSe layer

β-Ga2O3 nanowires were grown by thermal oxidation of GaSe single crystal surface under a mixture of argon–air flow, without the presence of a catalyst or foreign substrate. The nanowires were obtained after annealing GaSe surface at different temperatures (720 °C, 850 °C and 930 °C) for 5 h and they were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and selected area diffraction pattern. The lengths of the nanowires varied in the range 50–180 nm, while the typical diameters of the nanowires were in the range 60–90 nm. A possible mechanism has been proposed in order to explain the growth of oxide nanowires.