Persistence photoconductivity in ZnO thin films

Abstract

The thin films of ZnO is becoming very popular in designing the optoelectronic devices and sensors. It is a strong contender among all other transparent conducting oxides because of its high transparency, wide bandgap and low cost. However, the persistence of photocurrent in the ZnO films-based detectors is a common observation whose presence is responsible for the poor functioning of these devices. In this work, thin films of ZnO were deposited on the glass substrates by RF magnetron sputtering at room temperature. Two sets of samples were prepared in this work- sputtering power was varied as 75,125 and 175W for one set of samples while sputtering power was fixed at 75 W and the growth time was varied as 5,15,30,60 and 120 minutes for other set of samples. The structural and optical properties of thin films were studied by XRD and UV-Visible spectrophotometer. The prepared films were highly transparent to the visible region with transmittance more than 80%. Further, a brief literature study is given in order to understand the origin of PPC. The possible ways to reduce the PPC effect such as injection of plasmonic nanoparticles in ZnO matrix can be applied to improve the working of devices which endure the PPC.