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 (Y Ox) double gate insulator films. The minimum PVP and Y Ox layer thicknesses were chosen to be 45 and 50 nm, respectively. The PVP and Y Ox double dielectric layers with the minimum thicknesses exhibited a high dielectric capacitance of 70.8 nF cm2 and quite a good dielectric strength of ∼2 MVcm at a leakage current level of ∼ 10-6 A cm2 while the leakage current from either PVP or Y Ox alone was too high. Our pentacene TFTs with the 45 nm thin PVP50 nm thin Y Ox films operated at -5 V showing a high field effect mobility of 1.74 cm2 V s and a decent on/off current ratio of 104. Our work demonstrates that the PVPY Ox double layer is a promising gate dielectric to realize low-voltage high-mobility organic TFTs.