Regulation of oxygen vacancies in nitrogen-doped Ga2O3 films for high-performance MSM solar-blind UV photodetectors†
Abstract
Gallium oxide (Ga2O3)-based solar-blind photodetectors (SBPDs) have shown promising applications. However, the concentration of native oxygen vacancies (VO) impacts the photoelectrical performance of Ga2O3 films. Herein, a nitrogen-doping method is proposed to decrease the concentration of VO in Ga2O3 films. Specifically, Ga2O3 thin films were grown by radio frequency magnetron sputtering using nitrogen-containing ceramic targets at different substrate temperatures ranging from room temperature to 800 °C. Furthermore, their structural, optical and electrical properties were systematically investigated. Since the concentration of VO in Ga2O3 films is largely lowered through introduction of nitrogen species at VO sites, the persistent photoconductivity effect is significantly restrained. As a result, N-doped Ga2O3 photodetectors exhibit large photo-to-dark current ratios (PDCRs) of 4.6 × 106, a high responsivity of 0.27 A W−1, a large external quantum efficiency of 132.5%, and a high specific detectivity of 6.6 × 1011 Jones at 900 μW cm−2 light intensities at 5 V. Moreover, the PDCRs and detectivity of a N-doped device are increased by 2.2 × 103 and 50.6 times, respectively, as compared to those of the undoped device. These results demonstrate that the regulation of VO by nitrogen-doping can effectively improve the photoelectric performance of the device, opening up new opportunities for fabricating high-performance SBPDs.