The Effect of Oxygen Partial Pressure during Active Layer Deposition on Bias Stability of a-InGaZnO TFTs*Supported by the National Basic Research Program of China under Grant Nos 2010CB327504, 2011CB922100 and 2011CB301900, the National Natural Science Foundation of China under Grant Nos 11104130 and 61322112, the Natural Science Foundation of Jiangsu Province under Grant Nos BK2011556 and BK2011050, and the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the NUPTSF Grant Nos NY213069 and NY214028. (July 2015)