Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection

摘要

Core-shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of approximate to 15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of approximate to 330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 x 10(3) to 2.05 x 10(4) A W-1), faster response speed (from 397 to 28 ms), and higher I-325nm/I-dark ratio (from 453 to 1.1 x 10(4)) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I-193nm/I-dark ratio and photoresponsivity are 300 and 381 A W-1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.