Electrostatic modification of oxide semiconductors by electric double layers of microporous SiO₂-based solid electrolyte

We have studied electrostatic modulation of InGaZnO₄ and indium-tin oxide (ITO) channel by using microporous SiO₂-based solid electrolyte as gate dielectrics in the field-effect transistors (FETs) structure. H₃PO₄-treated SiO₂-based solid electrolyte was found to be have a large capacitance (9.5 μF/cm²) due to the strong capacitive coupling by electric double layer(EDL) between H₃PO₄-treated solid electrolyte and active channel. High carrier densities (>10¹⁴/cm²) and large metallic conductivities (2180 S/cm) in InGaZnO₄ channel were electrostatically induced, while a metal-to-insulator transition (more than 6 orders of magnitude of channel resistance modulation) was observed in ITO channel by using such FET structure. Furthermore, device simulation based on an EDL model can also reproduce the transfer characteristics well. Our result provides a new opportunity for electrostatic modulation of the electronic properties in condensed matter.