Ultrathin Indium Oxide Thin-Film Transistors With Gigahertz Operation Frequency

The remarkable dc performance of ultra thin indium oxide transistors offers a path toward highperformance 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 (fT) among amorphous metal-oxide-semiconductor transistors is reported with simultaneously high maximum oscillation frequency (fmax). 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 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.