Synthesis of InAl-alloyed Ga2O3 nanowires for self-powered ultraviolet detectors by a CVD method

Abstract

Ga₂O₃ is a kind of wide-band gap semiconductor, which has great potential in deep ultraviolet detection because of its high efficiency and fast response. Doping can improve the photoelectric properties of Ga₂O₃ materials. In this paper, In and Al elements alloyed Ga₂O₃ nanowires (InAl-Ga₂O₃ NWs) were successfully grown on p-GaN using a cost-effective chemical vapor deposition method and a vertical structure. The GaN/InAl-Ga₂O₃ NWs p–n self-powered wide-gap UV photodetector (PD) was constructed based on sputtered gold film as the bottom and top electrodes, and spin coated with polymethyl methacrylate as the insulating layer in the vertical direction. The GaN/InAl-Ga₂O₃ UV PD exhibits excellent performances, including an extremely low dark current of 0.015 nA, a maximum photocurrent of about 16 nA at zero-bias voltage under 265 nm illumination, and a light-to-dark current ratio greater than 10³. The responsivity is 0.94 mA W⁻¹, the specific detectivity is 9.63 × 10⁹ jones, and the good fast response/attenuation time is 31.2/69.6 ms. The self-powered characteristics are derived from the internal electric field formed between p-type GaN and n-type InAl-Ga₂O₃ NWs, which is conducive to the rapid separation and transfer of photogenerated carriers. This work provides an innovative mechanism of high-performance metal oxide nanowires for the application of p–n junction photodetectors, which can operate without any external bias.