Record RF Performance of Ultra-thin Indium Oxide Transistors with Buried-gate Structure

Ultra-thin indium oxide (In
2
O
3
) from several nanometers to sub-nanometer thick has recently been revealed as an excellent n-type semiconductor channel material for back-end-of-line (BEOL) compatible transistors due to its low thermal budget, low subthreshold swing (SS), high on current and I
on
/I
off
ratio, and high mobility [1]–[3]. However, a critical question that has not yet been addressed is that of the maximum frequency at which these devices can operate, which will play a deciding role in their analog applications. This work reports for the first time the detailed radio frequency (RF) characterization of some of these In
2
O
3
RF transistors scaling down to 150 nm channel lengths.