Influence of weight ratio of poly(4-vinylphenol) insulator on electronic properties of InGaZnO thin-film transistor

Spin-coated organic PVP layers were used as dielectric layers in a-IGZO TFTs. Weight ratios of 20:1, 10:1, and 5:1 for PVP and PMF, a cross-linking agent, were used. The a-IGZO TFTs with the PVP:PMF ratio of 20:1 showed a large hysteresis in the I - V curve and C - V curve, the hysteresis increases with the increase of hydroxyl groups and also deteriorated the gate leakage current. In contrast, the devices with the PVP:PMF ratio of 5:1 dielectric displayed only small hysteresis. According to our experimental results, preventing the possible diffusion of hydroxyl-contained species in polymeric dielectrics is a very important factor in improving the electrical properties of high-performance a-IGZO TFT devices.