Ambipolar field-effect transistor characteristics of (BEDT-TTF)(TCNQ) crystals and metal-like conduction induced by a gate electric field

Ambipolar carrier conduction has been observed in a metal-insulator-semiconductor field-effect transistor made using (BEDT-TTF)(TCNQ) crystals. The temperature dependence of the source current with the applied positive gate voltage exhibits metal-like behavior at around room temperature. The metal-like conduction transforms into thermal-activation-type behavior below $240\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The ${I}_{\mathrm{S}}\text{\ensuremath{-}}{V}_{\mathrm{DS}}$ curve for an applied gate voltage of $80\phantom{\rule{0.3em}{0ex}}\mathrm{V}$ exhibited a corresponding change in the curvature below $240\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.