Low-voltage pentacene field-effect transistors with ultrathin polymer gate dielectrics

Organic field-effect transistors (OFETs) for low-voltage operation have been realized with conventional polymer gate dielectrics such as polyimides and cross-linked poly-4-vinyl phenols (PVPs) by fabricating ultrathin films. These ultrathin polymers (thickness $\sim 10\mathrm{nm}$ ) have shown good insulating properties, including high breakdown fields $(>2.5\mathrm{MV}∕\mathrm{cm})$ . With ultrathin dielectrics, high capacitances $(>250\mathrm{nF}∕{\mathrm{cm}}^2)$ have been achieved, allowing operation of OFETs within $-3\mathrm{V}$ . Pentacene OFETs with ultrathin PVP dielectrics exhibit a mobility of $0.5{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ , an on-off ratio of ${10}^5$ , and a small subthreshold swing of $174\mathrm{mV}∕\text{decade}$ when devices are operated at $-3\mathrm{V}$ .