Enhanced performance UV photodetectors based on the β-Ga2o3/GaN photodiode of the reversed substitution growth with introduction nucleation layer of GaON by oxygen plasma treatment

A high-performance β-Ga₂O₃/GaN ultraviolet photodetector with bias-tunable spectral response (the UVC band to the UVA-UVC band) is demonstrated. The device is fabricated via a new route of reverse substitution growth, combined with oxygen plasma treatment (OPT) to introduce a GaON nucleation layer for the β-Ga₂O₃ synthesis on the GaN surface. The effects of the nucleation layer on the subsequent transformation from GaN to β-Ga₂O₃ at high temperature under oxygen ambience were analyzed in detail. X-ray diffraction (XRD) confirmed that (−201) preferred oriented monoclinic phase β-Ga₂O₃ with narrow linewidths has been formed. Both oxygen vacancies (V_O) on the surface and the root mean square (RMS) of the surface roughness of β-Ga₂O₃ treated with OPT are reduced, as confirmed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), resulting in better interfacial contact with the electrodes. Meanwhile, the increase in internal V_O enhanced the conductivity of the material, thereby improving the photoelectric response performance. The metal-semiconductor-metal (MSM) device achieved ultra-high detection capabilities (responsivity = 653 A/W, detectivity = 2.9 × 10¹⁵ Jones) and response spectrum switches between solar-blind narrow band and broad UVA-UVC band by varying the applied bias. The transient response time was on the millisecond scale. In the vertical-type β-Ga₂O₃/GaN photodiode, the responsivity and detectivity of the photodetector reached 2.1 A/W and 7.2 × 10¹³ Jones with a fast transient response time (rise time = 0.24 ms, decay time = 17.1 ms) under a bias voltage of −10 V.