| Thin film transistor (TFT) is a kind of field effect device which consist of electrode metal layer, semiconductor active layer and the gate dielectric insulator layer. It is the core device of Liquid Crystal Display (LCD) and Active Matrix Organic Light Emitting Diode. Traditional amorphous silicon TFT has low field effect mobility; the manufacturing technique of Poly silicon TFT is complicated and costly, has grain boundary or poor uniformity, and it is difficult to product in large area. The production process is simple of organic thin film transistor, but it’s low field effect mobility or poor stability can’t meet the requirement of rapid development of Active Matrix Organic Light Emitting Diode or large size Liquid Crystal Display. Recently, the representative transparent amorphous oxide semiconductor thin film transistor amorphous Indium-Gallium-Zinc-Oxide have attracted much attention for it’s superiority compared with the conventional amorphous silicon TFT, like simple manufacturing technique, low deposition temperature (can be prepared at room temperature), high electron mobility(>10cm2/Vs), high transmission in visible light, high stability, good uniformity in large area and so on. It is expected to be core driver parts of the next generation display, so it will be of great importance to research the IGZO thin film transistors. The thickness and film quality of semiconductor active layer has direct impact on thin film transistors. In thin film deposition process there are many factors that can influence the quality of the film, the deposition pressure, deposition temperature, deposition power and Argon oxygen partial pressure ratio can directly affect the quality of the film; In order to get high quality indium gallium zinc oxide thin film transistor, it is important to choose the appropriate gate dielectric material. Gate dielectric requires low trap state density and can reduce the thin film transistor voltage, Dielectric/IGZO heterojunction valence band offset and the conduction band offset is the important basis to choose the appropriate gate dielectric. Therefore, in this thesis we study indium gallium zinc oxide film and device from the following three aspects:(1) IGZO thin films were deposited by ratio-frequency magnetron sputtering and the influence of different deposition condition on the thin film quality were studied, such as the different argon oxygen partial pressure ratio and deposition substrate temperature on the structure, morphology, optical and electrical properties of indium gallium zinc oxide thin film. As a result, it can be concluded that the change of oxygen argon partial pressure ratio can adjust the band gap of the IGZO film and increasing the deposition temperature can effectively improve the quality of the IGZO film.(2)HfTiO/IGZO and IGZO(N)/Si heterojunction were deposited using ratio-frequency magnetron sputtering and its valence band offset and conduction band offset was investigated. It is benefit to understand their electronic transmission mechanism and improve the performance of the IGZO related devices.(3)Al/HfOxNy/IGZO/Si/Al MOS and Al/IGZO/SiO2/Si/Al TFT devices were produced by radio-frequency magnetron sputtering and the effect of different nitrogen doping concentration on the electrical performance of MOS device was discussed. Results display that N doped into HfO2 film can improve the crystallization temperature, improve the dielectric constant of thin film, changing the band gap of the film, reduce the leakage current and improve the electrical properties of MOS devices. TFT have poor performance. Further work should be performed in future. |
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