Starch as ion-based gate dielectric for oxide thin film transistors

Abstract

Application of nature bio-materials in electronics represents an emerging field of science and technology that began a few years ago. For the dielectric of transistors, the ion-based electric double layer (EDL) gating has becoming the widely accepted theory of charge modulation with hydrated bio-polymer dielectrics. Herein, we report on the use of starch as the ion-based gate dielectric for oxide thin film transistors. Two types of starches, i.e., water-soluble starch and potato starch were studied either with or without the incorporation of glycerol. Important parameters including mechanical strength, surface morphology, specific capacitance and ion conductivity were analyzed in accordance with the molecular structure of starches. The transistor performance was found in close relation with the specific capacitance and ion conductivity of the starch dielectrics. Higher on/off ratio (2.6 × 106) and field mobility (0.83 cm2V−1s−1) were obtained with glycerol incorporated potato starch due to the advantage in capacitance and ion conductivity. Lower ion conductivity of the water-soluble starch on the other hand caused the large current hysteresis, so the current retention property was examined for the potential application as a memory element. Collectively, this work solidifies our knowledge on the material type, EDL gating mechanism and applicability of nature bio-material gated transistors.