Near-field thermal radiation between doped silicon grating and plate

Abstract

When radiating two bodies come close enough to catch evanescently decaying radiations at the interface, thermal radiation can exceed the blackbody radiation. Uniform micro-scale structures, especially grating structures, may induce additional radiation due to cavity mode resonance or magnetic polaritons. Due to the 'grating effects,' rigorous calculation is required to correctly simulate the heat transfer between gratings, and approximation considering only the near-field effect may be highly misleading. However, no research groups yet had meet experimental and theoretical approval of near-field radiation between grating structures. Here we suggest that the primary step should be in verifying whether the rigorous calculation of near-field thermal radiation in grating structures successfully agrees with the experiment. For this purpose, the narrowest grating fabricable by UV-lithography was patterned, and etched with deep reactive ion etching for the 7.3-$\mu$m depth. Phosphorous-doped silicon was deposited with low pressure chemical vapor deposition. Finally, this grating sample and a planar sample were brought down to 320 nm vacuum gap to observe near-field thermal radiation. The observation was compared with the proximity approximation, and thus the primary step for future experiment to compare with rigorous calculation was made.