High Performance and High Stability ZnO Thin Film Transistors

• Main Authors: Meng-Lun Wu, 吳孟倫
• Other Authors: 黃建璋
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/49694776081582444575

碩士 === 國立臺灣大學 === 光電工程學研究所 === 96 === This 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. The 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. In 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.