An Ultrahigh‐Contrast Violet Phosphorus Van der Waals Phototransistor

Abstract Ultrahigh‐contrast photodetection with low background noise is of critical importance for accurate image‐sensing in deep‐sea and deep‐space exploration. The state‐of‐the‐art silicon and III–V semiconductor‐based photodetectors usually require extended exposure to incident light for high‐quality sensing in darkness, which unfortunately results in large room temperature dark currents ( RT ‐ I dark ) and deteriorates the expected imaging contrasts. Herein, a high‐performance violet phosphorus (VP) phototransistor is reported by constructing a trap‐free interface between the VP channel and hexagonal boron nitride ( h ‐BN) dielectric via perfect van der Waals stacking. The device shows an extremely low RT ‐ I dark of 80 fA and gate‐tunable high ON/OFF ratio over 10 5 , which is 2–4 orders of magnitude superior to that of conventional counterparts. A VP photodetector array has been fabricated to demonstrate the high‐contrast image‐sensing capability. The findings demonstrate the effectiveness of VP in low background noise and ultrahigh‐contrast image‐sensing applications, while also presenting exciting opportunities to enhance interface qualities through van der Waals architectures for high‐performance optoelectronics.