Controllable growth of GeO_2 nanowires with the cubic and hexagonal phases and their photoluminescence

摘要

Single crystalline GeO_2 nanowires with the cubic and hexagonal structures were synthesized via heating Germanium wafer coated with an Au film at 500-600 ℃ under the flow of H_2O vapor/N_2. The Germanium wafer was used as both reagent and substrate for the growth of GeO_2 nanowires. The control over the GeO_2 nanowires with the cubic and hexagonal phases, the diameters of 30-75 nm and the lengths of 2.5-200 nm can be achieved by varying the heating temperature and time. The GeO_2 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 GeO_2 nanowires, which indicate that the GeO_2 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.