5.1 Double-Gate Design

The operation of CNT-FETs can be described in terms of carrier injection through the SCHOTTKY barrier at the metal-CNT interface (see Section 2.8.2). However, the ambipolar conduction results in performance limitation [64,262,261]. In this section the ambipolar conduction is studied in detail. Then, a double-gate design is proposed to suppress this behavior effectively. The first gate controls carrier injection at the source contact and the second one controls carrier injection at the drain contact, which can be used to suppress parasitic carrier injection. The effect of the second gate voltage on the performance of the device has been investigated. Our results indicate that by applying a proper voltage range to the second gate improved device characteristics can be achieved.


M. Pourfath: Numerical Study of Quantum Transport in Carbon Nanotube-Based Transistors