The chiral properties of carbon nanotubes provide them with unique optoelectronic capabilities, making them highly sought-after one-dimensional nanoscale structures. CNTFETs can achieve outstanding ballistic transport at lower temperatures. Devices similar to MOSFETs would undeniably benefit from CNT's optoelectronic and low scattering characteristics. This investigation presents a highly efficient CNT transistor modeling technique. The approach employs the cubic spline estimation to analyze the impact of oxide thickness and dielectric material on the electric conduction of a nanoscale regime Schottky barrier CNTFET under ballistic consequences. By varying the dielectric constant of the insulator from a range of 3.9 to 30 while keeping the temperature at 100k and the gate voltage (V GS ) at 0.4 V, the drain current (I DS ) of a carbon nanotube (CNT) with a diameter of 1 nm increases by approximately 5 times when the drain voltage (V DS ) is set to 0.6 V. Similarly, when the gate voltage (V GS ) is increased to 0.65 V, the drain current (I DS ) increases by approximately 4 times, and when the gate voltage (V GS ) is further increased to 0.9 V, the drain current (I DS ) increases by approximately 3 times. The effect of tube diameter of CNT, oxide thickness, and DOS function is also evaluated.