Ultraviolet photodetectors based on colloidal ZnO quantum dot-graphene nanocomposites

Abstract

ZnO nanoparticles have emerged as excellent candidates due to potential applications in ultraviolet (UV) photodetector devices with a high photoresponse[1]. Currently, the UV photodetectors based on ZnO nanomaterials have been of current interest because of their potential applications in next-generation optoelectronic devices, such as sensors, optical communication systems, and missile launch detectors[2]. Due to high conductivity, good transparency, and high chemical and thermal stability[3], the graphene layers have emerged as excellent planar electrodes for promising applications in next-generation electronic and optoelectronic devices[4]. The graphene layers play very important roles as carrier transport layers and as electrodes for ultrafast photodetectors. In this study, Ultraviolet (UV) photodetectors were fabricated using the wet spin-coating for ZnO quantum dots (QDs) and the transfer method for the graphene sheet. High-resolution transmission electron microscopy images showed that the ZnO QDs were uniformly distributed between the voids of the surface circumferences on the graphene layers. Current-voltage measurements on the UV photodetector at 300K showed that the ratio of the photocurrent to the dark current was about 1.1×104. The rise and the decay times of the UV photodetector were approximately 2 and 1 s, respectively.