Ultrashort 15-nm flexible radio frequency ITO transistors enduring mechanical and temperature stress.

Flexible radio frequency (RF) transistors play an important role in the fast-growing wearable smart sensors for data communication. However, the scaling capability and high-speed performance of the flexible transistor are far below the counterparts on rigid substrates, impeding the gigahertz high-speed applications. Here, we address the scaling and performance bottlenecks in flexible transistors by demonstrating natively flexible RF indium tin oxide transistors with deeply scaled 15-nm-long channel, capable of operating in the 10-GHz frequency range. The record-high cutoff frequency of 11.8 GHz and maximum oscillation frequency of 15 GHz can rival those on rigid substrates. Furthermore, the robustness of flexible RF transistors was examined, capable of enduring heavy-duty 10,000 bending cycles at 1-mm radius and extreme thermal stress from cryogenic temperature of 4.3 K and high temperature of 380 K.