Thickness modulation effects of Al2O3 capping layers on device performance for the top-gate thin-film transistors using solution-processed poly(4-vinyl phenol)/Zn-Sn-O gate stacks

Abstract

Solution-processed Zn-Sn-O (ZTO) top-gate thin-film transistors with Al2O3/poly(4-vinyl phenol) (PVP) double-layered gate insulators (GI) were fabricated and characterized. ZTO active channel was formed by spin-coating method and activated at a temperature as low as 350 °C. The chemical damages for the PVP films, which were induced during the photolithography-based patterning process were effectively suppressed by the introduction of Al2O3 capping layer. This capping layer also played an important role in improving the drain current hysteretic behaviors caused by intrinsic properties of the PVP film by modulating the capacitance coupling in the double-layered GI. The carrier mobility, subthreshold swing, and on/off ratio were obtained as approximately 5.13 cm2V−1s−1, 0.36 V/dec, 7.03 × 106, respectively, with hysteresis-free characteristics when the thickness values of Al2O3 capping and PVP GI layers were designed to be 90 and 220 nm, respectively.