AbstractThe tradeoff between ultrahigh speed and low power is a dominant challenge in continuously improving modern electronics. Fundamental electronic devices with ultrafast response are highly desired in low‐power electronics. However, conventional semiconductor electronic devices now near the speed limit from the physical roadblocks including short‐channel effect, restricted carrier velocity, and heat death. Currently emerging electronic devices also face formidable difficulties to achieve high‐speed performance at low operating voltage without heat disturbance. Here, a novel fabricated coplanar tip‐to‐edge semiconductor‐free nanostructure with asymmetric sub‐10 nm air channel is reported, stimulating electric‐field accelerated scattering‐free transport of electrons and resulting in ultrafast response of record sub‐picoseconds at a low turn‐on voltage around 0.7 V. Simulation results show a typical electrical response down to 64 fs, which is ≈103 times faster than that of conventional semiconductor electronic devices. The coplanar asymmetric nanostructure allows a high rectifying ratio up to 106 which is superior to that of the most promising 2D semiconducting nanodiodes. In addition, heat death is overcome due to the inherent advantages from the novel nanostructure and underlying working mechanism. The intriguing nanodiodes will attract broadly interests in electronics due to their potential as rudimentary building blocks in ultrafast electronic integrated circuits.