All transparent high-performance solar-blind n-ITO/p-NiO-ZnO ultraviolet heterojunction bipolar phototransistor

摘要

All transparent high-performance solar-blind n-ITO/p-NiO-ZnO ultraviolet heterojunction bipolar phototransistors (HBPTs) were fabricated using a low-cost radio frequency magnetron sputtering system. In the HBPT structure, ITO, NiO, and ZnO were employed as the emitter, base, and collector, respectively. The applied voltage is across the emitter and collector, and the base is floating. The photocurrent increases with the collector-emitter voltage (V_(CE)). The prepared HBPTs presented the highest optical gain of 7.4 × 10~4 and a responsivity of 1.67 × 10~4 A/W, at V_(CE) = 4 V for the 280-nm illumination wavelength. As V_(CE) exceeds 4 V, the optical gain and responsivity decrease owing to the punch-through effect. The prepared HBPTs have an ultraviolet (UV)Msible rejection ratio of more than three orders, allowing their use in practical applications as UV detectors for weak UV signals.