Combined effects of NH3 and NF3 post plasma treatment on the performance of spray coated ZnO thin film transistors

Abstract

We investigate the effects of NH3 and NF3 post plasma-treatment on the performance of spray-coated ZnO thin film transistors (TFTs). Both NH3 and NF3 plasma treatment are varied from 10 to 40 s. The properties of plasma treated ZnO were studied by Hall Effect measurements, UV–visible spectroscopy, photoluminescence, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. NF3 plasma treatment causes n-type doping and generates carriers by F incorporation. While, NH3 plasma can cause not only n-type doping by Hydrogen incorporation but also creates acceptor-like states by the formation of Vo–H complex and inducing Nitrogen in ZnO. Owing to the N incorporation, the threshold voltage can be controlled by NH3 plasma treatment. The appropriate NH3 and NF3 plasma treatments for 10 s each greatly enhance theperformance of ZnO TFTs, exhibiting the saturation mobility and subthreshold swing of 20.65 cm2 V−1 s−1 and 0.18 V dec–1, respectively. Therefore, it is concluded that NH3 and NF3 plasma-treatment can be a useful technique to enhance the device performance and to improve the stability of solution-processed metal-oxide TFTs.