Nanometre-thin indium tin oxide for advanced high-performance electronics.

Although indium tin oxide (ITO) is widely used in optoelectronics due to its high optical transmittance and electrical conductivity, its degenerate doping limits exploitation as a semiconduction material. In this work, we created short-channel active transistors based on an ultra-thin (down to 4 nm) ITO channel and a high-quality, lanthanum-doped hafnium oxide dielectric of equivalent oxide thickness of 0.8 nm, with performance comparative to that of existing metal oxides and emerging two-dimensional materials. Short-channel immunity, with a subthreshold slope of 66 mV per decade, off-state current <100 fA μm-1 and on/off ratio up to 5.5 × 109, was measured for a 40-nm transistor. Logic inverters working in the subthreshold regime exhibit a high gain of 178 at a low-supply voltage of 0.5 V. Moreover, radiofrequency transistors, with as-measured cut-off frequency fT and maximum oscillation frequency fmax both >10 GHz, have been demonstrated. The unique wide bandgap and low dielectric constant of ITO provide prospects for future scaling below the 5-nm regime for advanced low-power electronics.