Optimal design and coulomb blockade suppressed leakage of carbon nanotube transistors

We consider a 1.5 nm diameter (19,0) CNT for which zero-Schottky-barrier contacts have been demonstrated. The model device has a wrap-around gate, 2 nm ZrO₂ dielectric, and the Fermi level of the metal contacts aligned with the conduction band of the source and drain. A number of different CNT lengths with various source/drain asymmetry are studied. A 40 nm length CNT with a 10 nm gate shows excellent performance as quantified below. We numerically calculate the gate delay (tau_s = C₉V_DD/I_ON), ON/OFF current ratio, and inverse subthreshold slope as a function of source to gate underlap L _exS