Simulation-Based Performance Analysis of Auxetic Lonsdaleite Toroidal Mesh Structures for Thermal Management and Mechanical Resilience in GaN HEMT Devices

This preprint presents a simulation-based investigation of auxetic toroidal mesh structures fabricated from lonsdaleite for applications requiring combined thermal management and high-strain mechanical performance, with particular relevance to high-power Gallium Nitride (GaN) High-Electron-Mobility Transistors (HEMTs). High-fidelity numerical simulations were conducted to evaluate the multi-physics response of the proposed architecture under conditions representative of high-power device operation. Key results include a reduction in effective heat generation from a 12.4% baseline to 41.5%, alongside 92% absorption of incoming kinetic energy with structural sacrifice maintained below 8%. The design leverages the exceptional stiffness of lonsdaleite (Young’s modulus ≈ 1,229 GPa) combined with auxetic behavior (target Poisson’s ratio ν = −0.5) and localized piezoelectric response. All simulations were performed using established models of elasticity, fracture mechanics, and thermal transport, with material parameters drawn from published lonsdaleite data. This work provides a technical foundation for advanced material solutions in wide-bandgap semiconductor thermal management.