Low-voltage transparent SnO2 nanowire transistors gated by microporous SiO2 solid-electrolyte with improved polarization response

Abstract

Low-voltage transparent SnO2 nanowire transistors gated by microporous SiO2 solid-electrolyte are fabricated using a nickel grid as a shadow mask. The operating voltage is found to be as low as 1.5 V due to the large gate capacitance (∼2 μF cm−2) related to the mobile ions-induced electric-double layer (EDL) effect. The polarization mechanism of microporous SiO2 solid electrolytes is studied and three polarizations (EDL formation, ionic migration, and dipole relaxation) at different frequencies are identified. The polarization response is optimized and the improved specific capacitance is 1 μF cm−2 at 1 kHz. The field-effect mobility, current on/off ratio and subthreshold swing are estimated to be 175 cm2 V−1 s−1, 105, and 116 mV/decade, respectively. The static and dynamic bias stress measurements indicate that transparent SnO2 nanowire FETs can operate at low-voltage with highly reproducibility. Such high-performance, low-voltage SnO2 nanowire transistors hold promise for novel device applications, such as portable ion-sensitive sensors.