Near-field thermal radiation between doped silicon plates at nanoscale gaps

Radiative heat transfer can be significantly enhanced via photon tunneling through a nanometer-scale gap to the point that it exceeds the blackbody limit. Here we report quantitative measurements of the near-field thermal radiation between doped-Si plates ($\text{width}\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}480\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\text{m}$ and $\text{length}\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}1.34\phantom{\rule{0.28em}{0ex}}\mathrm{cm}$). A novel MEMS-based platform enables us to maintain doped-Si plates at nanoscale gap distances that cannot be achieved by other methods. The measured radiative heat transfer coefficient was found to be 2.91 times greater than the blackbody limit at a 400-nm vacuum gap.