Vertical α/β-Ga2O3 phase junction nanorods array with graphene-silver nanowire hybrid conductive electrode for high-performance self-powered solar-blind photodetectors

Abstract

Gallium oxide semiconductor, with a bandgap energy of 4.9 eV, is regarded as a hopeful candidate for next-generation solar-blind photodetectors. However, the construction of photodetector based on Ga2O3 pn junction is still challengeable due to immature doping technology of p-Ga2O3. By considering the small lattice mismatch (＜3%) and similar band gap structure of α-Ga2O3 and β-Ga2O3, a well-designed solar-blind photodetector was built, based on vertical α/β-Ga2O3 junction nanorod arrays (NRAs) with a graphene-silver nanowires (Ag NWs) hybrid top electrode. Thanks to the high conductivity and optical transmittance of graphene-Ag NWs top electrode, the photodetector based on α/β-Ga2O3 junction NARs displayed excellent photoelectric performance. Meanwhile, the matched band structure of Π type formed at the interface of α/β-Ga2O3 junction promoted the automatic separation of photogenerated carriers and their transfer to the corresponding electrodes. A fast photoresponse time of 0.54 s, a high light-to-dark ratio about 2000, and a high rejection ratio (R254/R365) of 2.7 × 103 under the zero bias, were realized. The excellent photoelectrical performance of α/β-Ga2O3 junction photodetector even in vacuum environment forecasts its potential application in some low air density fields, such as missile early warning and tracking and ozone hole monitoring.