Meshed doped silicon photonic crystals for manipulating near-field thermal radiation

Highlights: • Significant enhancement in near-field thermal radiation is realized using practical and achievable micrometric gap, rather than nanometric gaps considered in majority of literature. • Near-field thermal radiation between meshed photonic crystal structure is investigated, for the first time in literature. • Enhancement in radiative heat transfer for meshed structures is 22 times higher than non-meshed ones, which is promising for thermal rectification and thermal management applications. • First-principle method is used to simulate the random thermal vibrations of charges within the material (i.e., the main mechanism of electromagnetic thermal emission). • Resonant modes validated and visualized by solving Helmholtz equation using weak-form formulations. - Abstract: The ability to control and manipulate heat flow is of great interest to thermal management and thermal logic and memory devices. Particularly, near-field thermal radiation presents a unique opportunity to enhance heat transfer while being able to tailor its characteristics (e.g., spectral selectivity). However, achieving nanometric gaps, necessary for near-field, has been and remains a formidable challenge. Here, we demonstrate significant enhancement of the near-field heat transfer through meshed photonic crystals with separation gaps above 0.5 µm. Using a first-principle method, we investigate the meshed photonic structures numerically via finite-difference time-domain technique (FDTD) along with the Langevin approach. Results for doped-silicon meshed structures show significant enhancement in heat transfer; 26 times over the non-meshed corrugated structures. This is especially important for thermal management and thermal rectification applications. The results also support the premise that thermal radiation at micro scale is a bulk (rather than a surface) phenomenon; the increase in heat transfer between two meshed-corrugated surfaces compared to the flat surface (8.2) wasn't proportional to the increase in the surface area due to the corrugations (9). Results were further validated through good agreements between the resonant modes predicted from the dispersion relation (calculated using a finite-element method), and transmission factors (calculated from FDTD).