CVD approach to a single gallium oxide nanowire for solar-blind UV detector.

Abstract

Finding a simple, energy-saving and low-cost synthesis method to process gallium oxide nanowires by CVD for solar-blind detector. Due to a bandgap of 4.5 ~ 4.9eV and a high breakdown field strength of 8 MV/cm, gallium oxide (Ga2O3) has great application prospects in solar blind ultraviolet detection and high-power devices. Notably, Ga2O3 NWs are currently the key research objects of solar-blind UV detection materials because of the characteristics of efficient photocarrier separation and collection, and the bandgap width perfectly matches the energy of deep ultraviolet photons. To find a simple method to synthesis Ga2O3 nanowire with smooth surface and uniform diameter, and the prepared single gallium oxide nanowire UV detector has high photoelectric conversion efficiency. Ga2O3 NWs are prepared on the SiO2/Si substrate by chemical vapor deposition (CVD) approach at low reaction temperature with gold particles serveing as the catalyst and gallium arsenide (GaAs) as a gallium source. X-ray diffraction and Raman spectroscopy characterization indicate the crystal structure of NWs is β-Ga2O3, and scanning electron microscope (SEM) characterization proves that the NWs have uniform diameter and smooth surface. Moreover, the high-resolution transmission electron microscopy (HRTEM) characterization shows that the material had high crystal quality. And the photoconductive solar-blind UV detector with a single Ga2O3 NW is prepared, showing the excellent performance of the high responsivity and external quantum efficiency. The effects of growth temperature and the size of gold catalyst on the morphology of β-Ga2O3 NWs have been investigated. The results show that with the reaction temperature is 625℃ and the diameter of Au catalyst is about 30~50 nm, it is more conducive to the formation of NMs with crystal structure, smooth surface and uniform diameter. And the performance of the solar-blind UV photodetector show that the device has higher sensitivity (R=149.82A/W), external quantum efficiency (EQE=73206%), response rate τrise=0.66s, and τdowm=0.45s.