Ultrahigh Responsivity β-Ga2O3/BP Junction Field Effect Phototransistors for UV/IR Dual-Band Detection

In this work, a dual-band junction field effect phototransistor (JFEPT) was fabricated by integrating p-type black phosphorus (BP) with Si-doped $\beta $ -Ga ₂ O ₃ . The operation principle of the JFEPT was systematically investigated by commercial TACD software SILVACO. The results indicate that the photocurrent is mainly formed by electrons under short-wave radiation, while it is composed of electrons and holes under long-wave irradiation. In addition, the Ga ₂ O ₃ doping concentration was determined to be $3\times 10^{{16}}$ cm $^{-{3}}$ to obtain a large photo-to-dark current ratio (PDCR). The threshold voltage ( ${V}_{\text {th}}{)}$ of the fabrication JFEPT was 0.65 V, indicating that the device working in normally- OFF state. The drain current was $\sim 10^{-{6}}$ mA/mm and the ON/ OFF ratio is $10^{{5}}$ at ${V}_{G}$ = −4 V and ${V}_{\text {DS}}$ = 5 V. And the device exhibits a low leakage current of $2.84\times 10^{-{6}}$ mA/mm. Under 254- and 808-nm illumination, the PDCR were 14713.79 and 5.53, and the responsivity was calculated to be $2.39\times 10^{{6}}$ and 535 mA/W, respectively. In addition, a low noise current of 0.17 nA/Hz $^{\text {1/{2}}}$ at 1 Hz is beneficial for the device to detect the ultraweak optical signal. This work provides an important reference for the realization of high-performance UV-IR dual-band detector.