一维纳米氧化锌自驱动紫外探测器的构建与性能研究

本文通过化学气相沉积法制备了ZnO纳米材料, 利用扫描电镜、光致发光谱、X衍射光谱及拉曼光谱等方法对制备的材料进行了表征. 基于制备的单根ZnO线分别构建了三种不同结构的紫外探测器件: Ag-ZnO-Ag肖特基型、PEDOT:PSS/n-ZnO结型和p-Si/n-ZnO结型紫外探测器, 并对器件的性能进行了研究. 结果表明: 三种不同结构的器件都表现出良好的整流特性, 对紫外线均有明显的光响应; 在零偏压下, 都有明显的自驱动特性. 三种器件中, p-Si/n-ZnO型紫外探测器性能最为优异: 在零偏压下, 暗电流约在1.2×10^-3 nA, 光电流在5.4 nA左右, 光暗电流比为4.5×10³, 上升和下降时间分别为0.7 s和1 s. 通过三类器件性能比较, 表明无机p-Si更适合与ZnO构建pn结型自驱动紫外探测器.

Frabrication and properties of self-powered ultraviolet detectors based on one-demensional ZnO nanomaterials

ZnO micro/nanowires were synthesized by chemical vapor deposition method. The morphology and structure of the products have been characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL) and micro-Raman scattering spectrometer, etc. Results show that the surface of the highly uniform ZnO wire is smooth and the as-synthesized ZnO wires show high crystal quality. Three types of UV detector are constructed using a single ZnO nanowire with different contact characteristics, and their corresponding performances are investigated systematically by using Keithley 4200-SCS and other equipments. All of the three different devices exhibit good rectifying characters and significant responsivity to ultraviolet light. The devices show self-driven features at zero bias. Compared with the devices made from Schottky contact and ZnO/PEDOT:PSS film, the present single ZnO nanowire/p-Si film devices with heterojunctions have the best self-powered function, which can be attributed to the stronger built-in electric field as well as the smaller dark current due to the insulating layer on the p-Si film. At zero bias, the fabricated ZnO nanowire/p-Si film device can deliver a dark current of 1.2×10^-3 nA and a high photosensitivity of about 4.5×10³ under UV illumination. The response of the devices made from ZnO nanowire/p-Si film to UV illumination in air is pretty fast with the rise time of about 0.7 s and the fall time of about 1 s, which could be attributed to the fact that the photo-generated electron-hole pairs in the depletion layer is quickly separated by the built-in electric field, leading to a rapid response speed and a larger photocurrent. Comparison among the three kinds of devices indicates that the devices made from ZnO nanowire/p-Si film are the best candidate for UV detectors.