This book employs the FETToy code to investigate and compare the electrical characteristics of carbon nanotube field-effect transistors (CNT-FETs) and silicon nanowire field-effect transistors (SiNW-FETs) utilizing SiO2, ZrO2, and HfO2 as dielectric materials. The objective is to discern the impact of dielectric choices on the performance of these nanoscale transistors. The dielectric materials (SiO2, ZrO2, and HfO2) are systematically varied to understand their influence on device behavior. Results indicate that the choice of dielectric profoundly affects the electrical performance of both...