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

Steep‐slope devices are predicted to provide excellent quality for analog integrated circuit applications due to their high transconductance efficiency (gm/Ids) 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 gm/Ids 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 gm/Ids 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. [ABSTRACT FROM AUTHOR]