Low-voltage high-mobility pentacene thin-film transistors with polymer/high-k oxide double gate dielectrics

We report on the fabrication of pentacene-based thin-film transistors (TFTs) with poly-4-vinylphenol (PVP)/yttrium oxide (YOx) double gate insulator films. The minimum PVP and YOx layer thicknesses were chosen to be 45 and 50 nm, respectively. The PVP and YOx double dielectric layers with the minimum thicknesses exhibited a high dielectric capacitance of 70.8 nF/cm(2) and quite a good dielectric strength of similar to 2 MV/cm at a leakage current level of similar to 10(-6) A/cm(2) while the leakage current from either PVP or YOx alone was too high. Our pentacene TFTs with the 45 nm thin PVP/50 nm thin YOx films operated at -5 V showing a high field effect mobility of 1.74 cm(2)/V s and a decent on/off current ratio of 10(4). Our work demonstrates that the PVP/YOx double layer is a promising gate dielectric to realize low-voltage high-mobility organic TFTs.