An analytical approach to model capacitance and resistance of capped carbon nanotube single electron transistor

Abstract

The single electron transistor (SET) as a nanoscale transistor operates according to the electron tunneling via two tunnel junctions. Since selecting a suitable island material plays a key role in electron transfer through the tunnel junctions, in this research capped Carbon NanoTube (CNT) is utilized for the SET island which produces the quantum capacitance (CQ). Its low value decreases the total capacitance (CT). Subsequently the coulomb blockade (CB) energy and the critical temperature are reduced. Moreover the resistance of the capped CNT as a two dimensional material is very low thus its effect on the total resistance can be neglected. The result of an investigation on the capped CNT SET tunnel junction shows that the tunneling time of electron into or out of island decreases therefore the operation speed of capped CNT SET increases. Furthermore both the resistance and the quantum capacitance are modeled and analyzed. Comparison studies of proposed models indicate that the capped CNT length and applied bias voltage play effective roles on the resistance. Additionally the capped CNT SET is simulated and the capped CNT SET stability diagrams are analyzed. The simulation result shows that the lower capped CNT length exhibits a smaller coulomb diamond regions. The lower CB range leads to faster capped CNT SET and a better reliability can be achieved.