This paper discusses the quantum capacitance effect in single-wall conventional CNTFET devices. The analytical expression for quantum capacitance has been derived based on the normalized number of carriers/total charge density. The total charge density in the inverted channel is suppressed at large drain voltage but remains unaffected by introducing any new sub-band. Lowering the quantum capacitance in the CNTFET device is a major challenge to improve the performance of the device. Quantum capacitance takes lower value at higher sub-band when operated at low gate bias voltage. Lower quantum capacitance can be achieved for larger tube’s diameter due to reduced band gap and by controlling the BTBT (band-to-band tunneling) leakage current which is possible by choosing the proper dielectric material and gate oxide thickness.
