Vapor-liquid-solid growth and narrow-band ultraviolet photoluminescence of well-aligned GeO₂ nanowire arrays with controllable aspect ratios

GeO₂ nanowire arrays have been fabricated by thermal evaporation of Ge powder in air via a vapor-liquid- solid mechanism with Au as a catalyst. The GeO₂ nanowires are single crystalline with a hexagonal structure and have a controllable aspect ratio in the range of 23-167. The controllable synthesis of GeO₂ nanowire arrays with different aspect ratios was achieved by adjusting the heating temperature and time. Photoluminescence spectra of the GeO₂ nanowire arrays were measured at room temperature, and two ultraviolet emission peaks at 347 and 364 nm are observed for the first time, which indicates that the GeO₂ nanowire arrays may have potential applications in nanoscale photonic and electronic devices. Moreover, this vapor-liquid-solid growth process may be employed for synthesis of the highly oriented nanowire arrays of other oxides, and provides opportunities for both fundamental research and technological applications.