Boosting the performance of crossed ZnO microwire UV photodetector by mechanical contact homo-interface barrier

Abstract

One-dimensional (1D) micro/nanowires of wide band gap semiconductors have become one of the most promising blocks of high-performance photodetectors. However, in the axial direction of micro/nanowires, the carriers can transport freely driven by an external electric field, which usually produces large dark current and low detectivity. Here, an UV photodetector built from three cross-intersecting ZnO microwires with double homo-interfaces is demonstrated by the chemical vapor deposition and physical transfer techniques. Compared with the reference device without interface, the dark current of this ZnO double-interface photodetector is significantly reduced by nearly 5 orders of magnitude, while the responsivity decreases slightly, thereby greatly improving the normalized photocurrent-to-dark current ratio. In addition, ZnO double-interface photodetector exhibits a much faster response speed (∼ 0.65 s) than the no-interface device (∼ 95 s). The improved performance is attributed to the potential barriers at the microwire–microwire homo-interfaces, which can regulate the carrier transport. Our findings in this work provide a promising approach for the design and development of high-performance photodetectors.