黃建璋臺灣大學:光電工程學研究所吳孟倫Wu, Meng-LunMeng-LunWu2010-07-012018-07-052010-07-012018-07-052008U0001-2507200810423900http://ntur.lib.ntu.edu.tw//handle/246246/188503This thesis focuses on two aspects of ZnO thin film transistors, the post oxygen passivation on ZnO thin film and a delta structure of ZnO TFTs.he first part demonstrates a high-performance enhancement-mode ZnO TFT on a glass substrate. A post deposition oxygen passivation technique is proposed with the purpose to fill up oxygen vacancies in the upper part of the ZnO channel layer. Before realizing the TFT device, the characteristics of ZnO thin film are examined to find out the optimal deposition conditions. The ZnO thin film is deposited by RF magnetron sputtering with the presence of O2 at low deposition rate and low temperature. The optimum duration of oxygen passivation in this work yields a device with a drain-source current level 0.87mA under a bias condition VGS=5V and VDS=15V, Ion/Ioff ratio 1.4?106.n the second part, we insert a delta doped layer into the conventional channel layer, and proposed a delta doped ZnO TFT. This structure can improve the stability and the operating current. Before realizing the TFT device, we need to find an optimal condition to growth GZO and combine the two films (ZnO and GZO) as a good channel layer. The optimum structure of a delta doped ZnO TFTs in this work yields a device with a drain-source current level 3.4mA under a bias condition VGS=5V and VDS=14V.Contentshapter 1 Introduction 1ibliography 4hapter 2 Literature Review and Theory .1 Thin film transistors .1.1 Operation of thin film transistors 5.1.2 Oxide-semiconductor-based thin film transistors 9.2 Property of ZnO 11ibliography 18hapter 3 Characterizations of High-Mobility ZnO Thin Film Transistors with Post Sputtering Oxygen Passivation.1 Theory 20.2 Experimental and analysis 22.3 Results and discussion 26ibliography 30hapter 4 ZnO Based Thin Film Transistors with the Insertion of a Thin Ga-doped ZnO Layer.1 Theory 31.2 GZO material properties 33.3 Advantages of delta doped TFT.3.1 High drain current capability 34.3.2 Control of the threshold voltage 38.3.3 High intrinsic transconductance 39.4 Device fabrication 41.5 Results and discussion 42ibliography 48hapter 5 Conclusions and Recommendations for Future Work 50igure Contentshapter 1 Introduction ig. 1.1 The display application of flexible electronics 2hapter 2 Literature Review and Theory ig. 2.1 The cross-section of a MOS capacitor and corresponding energy band diagrams for several biasing conditions 6ig. 2.2 An n-channel accumulation-mode TFT operating in (a) pre-pinch-off and (b) post-pinch-off regime 7ig. 2.3 Crystal structure of wurtzite ZnO 13ig. 2.4 Energy levels of native defects in ZnO. The donor defects are Zni2?, Zni?, Zni, VO2?, VO?, VO and the acceptor defects are VZn'', VZn'' 15hapter 3 Characterizations of High-Mobility ZnO Thin Film Transistors with Post Sputtering Oxygen Passivationig. 3.1 Resistivity and room-temperature X-ray diffraction patterns of sample A, B, C and D 22ig. 3.2 AFM images of sample A, B, C and D 24ig. 3.3 Schematic diagram of a top-gate ZnO TFT 25ig. 3.4 IDS-VDS curves of samples E, F, G, and H 27ig. 3.5 IDS-VGS transfer curves of samples E and G 28hapter 4 ZnO Based Thin Film Transistors with the Insertion of a Thin Ga-doped ZnO Layerig. 4.1 A simple illustration of delta doped TFT structure 35ig. 4.2 The oxide capacitance Cox and the capacitance between the oxide interface and δ-layer Cδ 39ig. 4.3 Illustration of the device structure of a delta-GZO TFT 41ig. 4.4 IDS-VDS curves of a delta-GZO TFT (a) and a conventional ZnO TFT (b) The gate-source voltage was scanned from 0 to 5V with a step of 1V 42ig. 4.5 IDS-VGS transfer curves of a delta-GZO TFT and a conventional ZnO TFT 44ig. 4.6 Improve the dielectric layer of a delta-GZO TFT (a) the IDS-VDS modulation curves (b) IDS-VGS transfer curves. 46able Contentshapter 2 Literature Review and Theory able 2.1 Wide band gap-based TFTs, processing methods employed, and electrical performance characteristics for several different channel materials 10able 2.2 Properties of ZnO 12able 2.3 (a) The symbols for crystal MX (b) Reactions of defect ionization in ZnO 14136 bytestext/htmlen-US氧化鋅ZnOthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188503/1/index.html