Choice of flat-band voltage, VDD and diameter of ambipolar Schottky-barrier carbon nanotube transistors in digital circuit design

Performance of carbon nanotube field-effect transistors (CNFETs) is advancing rapidly with simple digital logic circuits demonstrated. Typical Schottky barrier (SB)-mode operation of CNFETs, however, results in ambipolar conduction and a minimum leakage current exponentially increasing with the CNT diameter and power supply voltage when the transistor size is reduced. Ambipolar conduction imposes constraints on conventional CMOS applications. In this paper, we have studied the applicability of ambipolar SB CNFETs in conventional CMOS circuit design. The choice of CNT diameter and optimal supply voltage corresponding to the diameter has been discussed.