Towards a nanofabricated vacuum cold-emitting triode

A technique to fabricate a vacuum cold-cathode nanoelectronic diode with a remarkably low 2-V turn-on voltage was recently presented. A three-terminal device based on the same technology is here designed and fabricated, to implement a vacuum nano-triode. The attempt was partially successful as the excessively large gate radius does not allow effective current control. Nonetheless, the obtained experimental results still disclose fundamental behaviors improving both the art and knowledge in the field. Specifically, it is found that: 1) thermionic field emission is ascertained both from a metal tip and from a silicon tip with a nearly 2-V turn-on voltage; 2) the gate current is negligible and the cathode current is efficiently collected by the anode, 3) emission is quite insensitive to temperature and the device can work also at high temperatures, observed up to 300 °C in a reliable manner. Finally, the unexpected bidirectional conduction can open a new scenario for the implementation of triac-like vacuum nanodevices.