Preparation And Characterization Of ZnO:N-TFT

Display devices have steadily become smaller and lighter,and both power consumption and performance have significantly increased,starting with CRT technology in the twentieth century and ending with the present dominant AM-LCD,AMOLED,and Mini LED technologies.The performance of the thin film transistor（TFT）,a crucial component of modern displays,is intimately correlated with that of the displays themselves.In comparison to silicon-based active layers（a-Si:H,poly-Si）,third-generation broadband semiconductor ZnO performs better optoelectronically as a thin-film transistor active layer.However,because of the inherent flaws in the active layer,the existing intrinsic ZnO thin-film transistors have low open-state current,a high threshold voltage,and poor stability.In this thesis,nitrogen-doped zinc oxide（ZnO:N）thin-film transistors were created utilizing magnetron sputtering and thermal oxidation procedures to enhance the performance of ZnO thin-film transistors.The major work is broken down into the following sections.Firstly,on quartz glass substrates,we deposited zinc nitride films using DC and RF magnetron sputtering coating techniques,and we investigated how the process variables affected how well the produced coatings performed.At a nitrogen-to-argon ratio of 40:20sccm,a sputtering power of 100W,and a substrate temperature of 200°C,the produced Zn₃N₂ thin film exhibits uniform grain size and good performance.Secondly,the obtained Zn₃N₂ films were thermally oxidized in a tube furnace at various oxidation temperatures and for various lengths of time to produce ZnO:N films.We characterized the properties of the ZnO:N films using SEM,UV-vis,XPS and XRD.It was found that the ZnO:N films prepared at different oxidation temperatures and oxidation times had a transmittance greater than 80%in the visible band,and there was a significant absorption edge near the near-UV.The grain size of the films slowly increased with the increase of oxidation temperature and time,and all of them exhibited good c-axis selective orientation.And with the increase of oxidation temperature both defect concentrations gradually decreased and approached.The SEM characterization reveals that the film’s surface is comparatively smooth,the grain size is uniform,and the highest grain size occurs after 30 minutes of oxidation at 700°C.Thirdly,we prepared ZnO:N thin films on p-type heavily doped silicon oxide substrates and vaporized Mo electrodes on ZnO:N thin films using an electron beam evaporation process.The electrical properties of the TFTs were characterized by using a Keithley 4200 semiconductor analyzer in an ambient air environment and dark conditions.The mobility and switching ratio of the thin film transistors were found to deteriorate with increasing oxidation temperature and oxidation time after testing the performance.