Transconductance Amplification in Dirac‐Source Field‐Effect Transistors Enabled by Graphene/Nanotube Hereojunctions

Abstract Steep‐slope devices are predicted to provide excellent quality for analog integrated circuit applications due to their high transconductance efficiency ( g m / I ds ) breaking the metal‐oxide‐semiconductor field‐effect transistor limit (38.5 V −1 ). The potential advantage of a Dirac‐source FET (DSFET) as an analog transistor is explored based on a graphene/carbon nanotube (CNT) heterojunction. A high g m / I ds beyond 38.5 V −1 over four decades of current is experimentally demonstrated in an individual CNT‐based DSFET, reaching a peak value of 66 V −1 , which is a new record for all reported transistors. Importantly, this high g m / I ds extends beyond the subthreshold region and leads to transconductance amplification in the overthreshold region. The best peak transconductance at a low bias of −0.1 V exceeds 20 µS per tube, which has approximately threefold improvement over that of a normal CNT FET with a shorter gate length. Outperforming other advanced devices, the extended high transconductance efficiency greatly promotes DSFET competitiveness in the high‐precision analog field.