OICC Press Majlesi Journal of Electrical Engineering 2345-3796 18 2 2024 06 03 Numerical Analysis of Diameter Dependency of Control Coefficient of Carbon Nanotube Field Effect Transistor 10.57647/j.mjee.2024.1802.37 EN Shaeekul Ameen Department of Electrical Electronic & Communication Engineering, Military Institute of Science & Technology, Dhaka, Bangladesh 0009-0003-9675-2193 Sayed Farhan Department of Electrical & Electronic Engineering, Ahsanullah University of Science and Technology, Dhaka, Bangladesh 0009-0000-4656-1397 Farhun Monsur Department of Electrical & Electronic Engineering, Ahsanullah University of Science and Technology, Dhaka, Bangladesh 0009-0001-7676-2234 Faysal Nayan Department of Electrical & Electronic Engineering, Ahsanullah University of Science and Technology, Dhaka, Bangladesh 0000-0001-9150-5829 Journal Article 2024 06 03 This study examines the behavior of carbon nanotube field effect transistors under ballistic conditions by analyzing the effect of gate (α_G) and drain (α_D) control coefficient modifications on the device's diameter. The effect of α_G and α_D on the outcome of CNTFETs has been thoroughly investigated, and the performance of the device has been evaluated using a variety of parameters for different diameters. In this CNTFET design, the lowest sub-threshold swing recorded is 60.7 mV/decade when using a lower CNT diameter which is 1 nm. The smaller value of sub-threshold swing is contributed by the highest value of gate control coefficient i.e. 0.98, which is desirable for a better ratio between the on- and off-currents and faster-switching device. Again, the maximum quantum capacitance obtained was 1.97×10-10 F/cm2 while utilizing a smaller CNT diameter of 1 nm. The maximum value of quantum capacitance is supplied by the value of the gate control coefficient, which is 0.83. Also, the highest transconductance measured, with a greater CNT diameter of 5 nm, is 14.50 uS. With a gate control coefficient of 0.98, the quantum capacitance reaches its maximum value. Overall, the sub-threshold swing decreases as the gate control coefficient increases, while it increases as the drain control coefficient increases. Again, as the gate control coefficient increases, the value of quantum capacitance decreases with a smaller diameter, whereas the quantum capacitance of the device does not fluctuate significantly with a larger diameter. When the diameter changes, the drain control coefficient undergoes an analogous transformation. Furthermore, an increase in the gate control coefficient causes the transconductance to increase. However, when the drain control coefficient is increased along with a change in diameter, the transconductance value remains almost unchanged. Thus, the ideal values for both control coefficients can be determined in this manner to ensure optimal performance.