An on-chip vacuum triode based on thermionic electron emission from super-aligned carbon nanotube films

An on-chip vacuum triode based on thermionic electron emission from suspended super-aligned carbon nanotube films is realized via microfabrication technology. The device employs a multilayer-stacked structure with an in-built vacuum cavity that separates the thermionic electron source and the collector electrode. The wafer-scale fabricated thermionic electron source exhibits an emission current of up to 200 μA with an emission density of 6.7 A cm⁻². To switch the emission current from the electron source to the collector electrode, the heavily doped silicon substrate underneath suspended carbon nanotubes works as the gate electrode, achieving an on/off current ratio of 10² and a subthreshold slope of ∼7 V dec⁻¹. Additionally, the vacuum triode exhibits good tolerance to harsh environments of high or low temperature and X-ray radiation. All these properties make the miniaturized vacuum triode a device with potential for application in harsh environments.