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 $\left(\mathrm{Y}{\mathrm{O}}_x\right)$ double gate insulator films. The minimum PVP and $\mathrm{Y}{\mathrm{O}}_x$ layer thicknesses were chosen to be 45 and $50\mathrm{nm}$ , respectively. The PVP and $\mathrm{Y}{\mathrm{O}}_x$ double dielectric layers with the minimum thicknesses exhibited a high dielectric capacitance of $70.8\mathrm{nF}∕{\mathrm{cm}}^2$ and quite a good dielectric strength of $\sim 2\mathrm{MV}∕\mathrm{cm}$ at a leakage current level of $\sim {10}^{-6}\mathrm{A}∕{\mathrm{cm}}^2$ while the leakage current from either PVP or $\mathrm{Y}{\mathrm{O}}_x$ alone was too high. Our pentacene TFTs with the $45\mathrm{nm}$ thin $\mathrm{PVP}∕50\mathrm{nm}$ thin $\mathrm{Y}{\mathrm{O}}_x$ films operated at $-5\mathrm{V}$ showing a high field effect mobility of $1.74{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ and a decent on/off current ratio of ${10}^4$ . Our work demonstrates that the $\mathrm{PVP}∕\mathrm{Y}{\mathrm{O}}_x$ double layer is a promising gate dielectric to realize low-voltage high-mobility organic TFTs.