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

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