<p>This study presents the design and simulation of silicon-based thyristors aimed as exploding foil initiator (EFI) switches. Although recent EFI switch designs focus on devices based on silicon carbide (SiC) due to its wider bandgap and superior thermal performance, our work returns to silicon, a material used in foundational studies in the field, offering a cost-effective alternative for thyristor-based EFI applications. In contrast to SiC-based devices that employ well-controlled epitaxial drift layers, the use of silicon necessitates the integration of the substrate wafer itself as the drift region of the thyristor. This introduces challenges related to doping uniformity, as bulk substrates exhibit greater variation compared to epitaxial layers. This study aims to optimize critical design parameters, including layer dimensions and doping concentrations, to mitigate the effects of wafer variability. TCAD simulations are used to evaluate device behavior, and results are compared with both similar EFI designs from the literature and a commercial product, focusing on key performance metrics such as <i>di/dt</i>, breakdown voltage, and turn-on delay. The findings indicate that the proposed designs achieve comparable or even superior performance. Additionally, the study explores the impact of device type (N-type vs. P-type), doping concentrations, layer dimensions and placements, as well as layout configurations (square vs. cylindrical) on device performance, marking a significant contribution. The results of this study will serve as a valuable resource for researchers developing high-energy switching devices.</p>