Work function consideration in vacuum field emission transistor design

Abstract

Effects of work function engineering on the electrical characteristics of nanoscale gate-all-around (GAA) vacuum field emission transistors (VFETs) is investigated using three dimensional technology computer aided design simulation. A low gate work function can be useful to reduce the threshold voltage suitable for lower power operation. As expected, the lower emitter work function GAA VFETs provide a reduced threshold voltage and an enhanced on-current due to the reduction of electron tunneling barrier height between the emitter and the vacuum channel. Even though a constant threshold voltage behavior has been observed with various collector materials, a higher collector work function can increase the tunneling barrier height nearby the collector side and mitigate carrier generation from the collector to vacuum, resulting in higher on-current with lower gate-leakage current.