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

Abstract

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 ≈15 nm is coated uniformly on the single‐crystal ZnO nanowire with diameters of ≈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 × 103 to 2.05 × 104 A W−1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark 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.

Self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on interdigitated electrodes for visible-light photodetectors

“…Hence, in the last years, core–shell heterojunction nanowires based on metal oxides emerged as promising new materials capable of encoding new and advanced functionalities that are essential for the next generation miniaturized nanowire based photodetectors 25 , 26 . Accordingly, various core–shell heterojunctions were used in order to fabricate photodetectors based on single (ZnO–Cu x O 27 , CuO–ZnO 28 , ZnO/ZnS 29 , ZnO/Ws 2 30 , ZnO/AlN 31 , etc.) or on arrays (ZnO–Cu 2 O 32 , ZnO/CuCrO 2 33 , ZnO/NiO 34 , ZnO–Co 3 O 4 35 , ZnO/SnO 2 36 , ZnO/Ga 2 O 3 37 , ZnO/Si 38 , etc.)…”

Self-Powered and Broadband Lead-Free Inorganic Perovskite Photodetector with High Stability

“…Among the important optoelectronic devices, UV detection plays an essential role in biological analysis, space exploration, environmental sensors, and UV irradiation detections. − In the past few decades, UV photodetectors with wide-band-gap semiconductors have been studied extensively owing to their suitable direct band gap and low cost, such as (Al) GaN, AlN, ZnO, − TiO 2 , − WO 3 , etc. However, Group III nitrides are usually synthesized via relatively expensive approaches such as vapor–liquid–solid or epitaxy, which accounts for their high cost and hence hampers their commercial application. , On the other hand, those photodetectors based on metal oxide suffer from persistent photoconductivity (PPC) caused by the surface and bulk deep-level defects, , resulting in long response tails.…”

Improved Photoresponse Characteristics of a ZnO-Based UV Photodetector by the Formation of an Amorphous SnO2 Shell Layer

“…As summarized in Table S1, the rise time and the fall time of most ZnO-based PDs are of the order of several seconds. Although some ZnO-based PDs have shown response times of milliseconds or microseconds, the fabrication processes used to improve the response properties require a high temperature of above 800 • C or a high-vacuum environment [15][16][17][18]. The slow light response speeds and high photoconductive gain exhibited by ZnO-based UV PDs are strongly related to the oxygen-mediated detection mechanism [19][20][21].…”

“…Accordingly, there is a trade-off between the high photoconductive gain and the fast light response speed. To improve their rise and fall times without degrading the photoconductive gain, introducing a shell layer to the ZnO core, such as AIN [18], Al 2 O 3 [22], InN [23], SnO 2 [24], PVA [25], CuCrO 2 [26], or TiO 2 [27], may be a promising solution, resulting in an improvement in the overall performance of PDs. However, forming the shell layer of these materials requires a high temperature and is a complex and expensive process.…”