Ultra-high PDCR(>10⁹) of vacuum-UV photodetector based on Al-doped Ga₂O₃microbelts

Al-doped Ga₂O₃microbelts with widths ranging from 20 to 154μm and lengths up to 2 mm were grown using carbothermal reduction. Based on these ultra-wide microbelts, single-microbelt (37μm wide) and double-microbelts(38μm/42μm wide) metal-semiconductor-metal photoconductive ultraviolet (UV) detectors PDs were fabricated and their optoelectronic performances were investigated at Vacuum-UV (VUV) wavelengths of 185 nm. Under irradiation of 185 nm, the Al-doped Ga₂O₃PD has a very-high photocurrent (I_ph) of 192.07μA and extremely low dark current (I_d) of 156 fA at 10 V, and presents a ultra-high light-to-dark current ratio of 1.23 × 10⁹. The responsivity (R), external quantum efficiency (EQE), and detectivity (D*) of the double-microbelts detector device were 1920 A W^-1, 9.36 × 10⁵%, and 8.6 × 10¹⁶Jones, respectively. Since the bandgap of the Al-doped microbelts becomes wider, and the fabricated detector has weaker sensitivity to radiation in the 254/365 nm wavelengths. Compared with the 254 nm and 365 nm UV cases, the devices under 185 nm VUV show the excellent high selectivity ratios of 1.47 × 10⁶and 1.7× 10⁷, respectively. This paper should provide a new insight on the VUV photodetectors utilizing Ga₂O₃microbelts.