Thin-film transistors (TFTs) based on oxide semiconductors have gained a lot of attention in applications such as displays and sensors particularly in recent years due to the advantages of oxide semiconductors like high mobility, good uniformity over large area and low deposition temperature[1-4].However, the defects/traps at dielectric/channel interface and top surface of oxide TFTs might dramatically degrade device performance including current on/off ratio, mobility and most importantly stability[5, 6], making it quite urgent to systematically make effective interface engineering to improve TFT performance.