Ultralow-Voltage Field-Effect Transistors Using Nanometer-Thick\nTransparent Amorphous Indium–Gallium–Zinc Oxide Films

Abstract

The design of solution-processed\ntransparent transistors with ultralow-voltage\noperations and a planar architecture can be a paradigm shift toward\nthe realization of ultralow-power electronic circuits due to conformity\nwith the existing complementary metal oxide semiconductor (CMOS) platform.\nWe report a robust and solution-based device fabrication protocol\nto demonstrate near-steep-slope transparent oxide field-effect transistors\n(TO-FETs) with operating voltages at or below 0.5 V using a nanometer-thick\namorphous indium–gallium–zinc oxide (a-IGZO) channel\nand an ultrathin anodized aluminum dielectric. The transmittance spectra\nconfirm the excellent transparency (>98%) of the a-IGZO thin film\nfor the entire visible range. Hysteresis-free transfer characteristics\nexhibit the film’s operation as an n-channel TO-FET with a\nlow threshold voltage (∼96 mV), a near-thermionic subthreshold\nswing (SS) down to 85 mV/dec, and a high ON/OFF current ratio (>10⁵). The consistency of these TO-FET results of ultralow-power\noperation with a near-steep-slope nature was demonstrated by enormously\nlarge specific capacitance values of ultrathin anodized aluminum gate\ndielectrics as the forcing factor. Moreover, half-volt operation of\nthe TO-FET is also flawlessly demonstrated at room temperature with\nhysteresis-free characteristics. Hence, these planar TO-FETs could\nbe a potential technological breakthrough for the future of cost-effective\nand high-performance transparent ultralow-power applications, including\nquantum and neuromorphic computation fields of research.