The utilisation of Carbon Nanotubes (CNT) as replacement material in the development of transistors in nanoscale regime seems to be the prominent choice in the present era. Schottky Barrier Carbon Nano Tube Field Effect Transistor (SB CNTFET) is one of the transistors developed using CNTFET amongst several other available choices. The performance of SB CNTFET for the better utilization of CNTFET in the nanometer regime depends on the several factors oxide thickness, high dielectrics, contact material and device geometry. In geometry the Gate structure is one of the important factors for SB CNTFET. This paper reports the impact of single gate and double gate SB CNTFET structure on the device performance. The impact on device performance of single and double gate structures is due to variations in parameters like chirality, oxide thickness, High-k dielectric and channel length. The comparison of results for the structures suggests that, there is increase in control over I _ON in case of double gate CNTFET. The subthreshold slope and I _ON/I _OFF ratio for double gate structure is better than single gate structure. The values for chirality, oxide thickness, dielectric constant and channel length have clearly shown betterment of device performance by approximately 10 percent in simulated results. Thus increasing the suitability of Double Gate (DG) structures primarily for low power digital circuit applications is requirement in case of fast switching operations.