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 (V_O) impacts the photoelectrical performance of Ga₂O₃ films. Herein, a nitrogen-doping method is proposed to decrease the concentration of V_O 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 V_O in Ga₂O₃ films is largely lowered through introduction of nitrogen species at V_O 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 V_O by nitrogen-doping can effectively improve the photoelectric performance of the device, opening up new opportunities for fabricating high-performance SBPDs.