Fabrication And Characterization Of α- NbZnSnO Film And Application In TFT Field

In 21st century, along with the deepening of human society information degree, ultra-thin, high-definition, large-size, energy-saving and transparent display technology is becoming more and more important, which even has become the foundation of one nation’s strategic high-tech industry. Amorphous silicon (a-Si) and low temperature poly silicon(LTPS) material,which are widely used in the industry, still have the disadvantage such as low carrier mobility and can’t be fabricated in large scale, while amorphous oxide semiconductors(AOSs) can nearly solve most of the problems as above, so AOSs are drawing more and more attention. Although some Korea and Japanese companies have already developed a-IGZO material and put it into application, in our country the related research is deadly lacking, therefore, it is particularly necessary to develop the related research within our country.In this paper rf-magnetron sputtering method is applied to fabricate α-NZTO films. To explore the optimum process parameters, sputtering pressure, sputtering power and subsequent annealing process are adjusted and applied. When sputtering pressure is 0.6Pa, sputtering power is 120W and annealled at 400℃ for 2 hour, the as-grow films can reach the best comprehensive performance in terms of material structure, surface roughness, electrical and optical properties. The XRD and HR-TEM measurement results reveal that all the as-grow films are amorphous, through UV-vis transmittance measurement, these films’transmittance are all above 80%. Hall-effect measurement revealed that with the increase of Nb contents, the earner mobility firstly increase then decrease and the carrier concentration decrease monotonously. The XPS measurement results demonstrat that the oxygen vacancy decrease with the adding of Nb contents, which indicat that the adding of Nb can indeed suppress the forming of oxygen vacancy.In the fabrication of TFT devices, a-NZTO films prepared by using the above optimum parameters are used as channel layer. This part mainly study the effect of annealing, oxygen pressure when sputtering, TFT channel length-width ratio and Nb doping contents on the performance of TFT devices. When oxygen pressure is OPa, channel length-width ratios is 1000:100, Nb doping ratio is 0.2 and consequent annealing process, TFT can reach the optimum performance, the carrier mobility μFE can reach to 048cm2s-1v-1, threshold voltage is-6.43V, subthreshold swing is 1.63V/decade, the on-off ratio is 1.9×107, and the annealing process can dramatically decrease the defect density of states within the interface between channel layer and insulator layer.