Ultrathin Indium Oxide Thin-Film Transistors With Gigahertz Operation Frequency

The remarkable dc performance of ultrathin indium oxide transistors offers a path toward high-performance back-end-of-line (BEOL) and monolithically integrated logic and memory devices for next-generation computing. Its very low thermal budget, high reliability, scalability, and 3-D conformality are additional factors that make these devices well-suited for these applications. Here, the radio frequency (RF) performance of indium oxide transistors with a high working frequency is characterized for the first time. A new record high cutoff frequency (
${f}_{T}$
) among amorphous metal–oxide–semiconductor transistors is reported with simultaneously high maximum oscillation frequency (
${f}_{\text {max}}$
). Detailed statistical measurements across a wide variety of channel lengths and gate overlaps provide insight into optimization of the device parasitics and future scaling trends. Even at relatively long channel lengths of 1
$\mu \text{m}$
, the operation frequency is sufficient for these devices to function alongside traditional silicon CMOS devices that are generally clocked at less than 5 GHz.