ZnO薄膜紫外探测器的光电性质

采用直流反应磁控溅射的方法制备ZnO薄膜, 用X射线衍射仪(XRD)、扫描电镜(SEM)和紫外-可见光谱仪(UV-Vis)分别表征ZnO薄膜的晶体结构和表面形貌等特征。并用此材料制备Au/ZnO/Au金属-半导体-金属(MSM)结构光电导型ZnO薄膜紫外光探测器。实验结果表明, ZnO探测器在360 nm出现明显光响应,其光电流为2.5 mA, 在5 V偏置电压下暗电流为250 μA; ZnO紫外探测器在250～380 nm的紫外波段, 探测器有很明显的光响应, 且光电流响应比较平坦; 在380～430 nm区域, 光响应明显下降; 其光响应的上升与下降弛豫时间分别为20 s与80 s。从光谱响应图中可以看出紫外(360 nm)比可见区(450 nm)的光响应高出3个数量级, 薄膜表面存在的缺陷(如氧空位)在ZnO紫外探测器的光电效应中有重要作用。

Photocurrent of Ultraviolet Photoconductive Detectors with ZnO Thin Film

ZnO thin film was prepared by direct current (DC) magnetron sputtering, whose properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet-visible spectrometer (UV-Vis). The photocurrent characteristics of the metal-semiconductor-metal (MSM) photoconductive ultraviolet detector with Au/ZnO/Au structure based on ZnO film were investigated. The results showed that ZnO UV detector had a higher photocurrent of 2.5 mA under the typical responsivity peaked at around 360 nm, the dark current was 250 μA with the applied bias of 5 V. In addition, ZnO UV detector also had a higher photocurrent at the wavelength from 250 nm to 380 nm, and photoresponse obviously reduced between 380 nm and 430 nm. And a slow photoresponse with a rise time of 20 s and a decay time of 80 s was achieved. The ratio of UV (360 nm) photoresponse to visible (450 nm) one is about three orders from the spectra response. The neutralization of photogenerated holes by negatively charged oxygen ions plays a key role in the photoconductive characteristics of ZnO films.