Controllable growth of GeO2 nanowires with the cubic and hexagonal phases and their photoluminescence

Single crystalline GeO2 nanowires with the cubic and hexagonal structures were synthesized via heating Germanium wafer coated with an Au film at 500–600 °C under the flow of H2O vapor/N2. The Germanium wafer was used as both reagent and substrate for the growth of GeO2 nanowires. The control over the GeO2 nanowires with the cubic and hexagonal phases, the diameters of 30–75 nm and the lengths of 2.5–200 μm can be achieved by varying the heating temperature and time. The GeO2 nanowires follow a top-Vapor–Liquid–Solid growth model. Ultraviolet, violet and blue emissions peaked at 351.9, 396.8 and 480.2 nm, respectively, are observed from the GeO2 nanowires, which indicate that the GeO2 nanowires may have potential applications in nanoscale photonic and electronic devices. This low temperature Vapor–Liquid–Solid growth process may be employed for the controllable synthesis of other oxide nanowires with different crystalline phases, and provides opportunities for both fundamental research and technological applications.

GeO2 nanowires with the cubic and hexagonal structures were synthesized at 500–600 °C.
► Control over the crystalline structures was achieved by adjusting the reaction temperature.
► The GeO2 nanowires with the cubic structures were obtained for the first time.
► The GeO2 nanowires exhibit ultraviolet, violet and blue light emissions.
► The unimodal violet emission peaked at 352 nm are observed for the first time.