SUMMARY

Near-field thermal radiation which can exceed blackbody radiation by several orders of magnitude has potential applications in energy conversion systems, near-field thermal microscopy, and nanomanufacturing. At the same time, the determination of emissivity of nanostructured materials is critical in many applications, such as radiation thermometry, microelectronics manufacturing, and radiative cooling. The proposed thesis aims at studying the near-field energy transfer between closely spaced plates and direct calculation and measurement of thermal emission from nanostructures. Infrared radiative properties of heavily doped Si are investigated near room temperature. Accurate carrier mobility and ionization models are identified via a critical review of available literature and then incorporated in to a Drude model to predict the dielectric function of heavily doped Si. The calculated radiative properties of several samples are then compared with those measured with a Fourier-transform infrared spectrometer. The dielectric function model is employed to calculate near-field radiative energy transport between two semi-infinite Si bodies. The effects of doping level, polarization, and vacuum-gap width on the spectral and total radiative transfer are studied based on fluctuation electrodynamics. The maximum achievable near-field heat transfer is then calculated between two parallel plates at finite vacuum gap. Attention is also paid to the direct and indirect methods for calculation of thermal emission from novel multilayered structures. The emissivity of fabricated samples will be measured using a high-temperature emissometer developed through this thesis research. The results obtained from this thesis will facilitate the future design of MEMS devices and applications of nanoscale radiation for energy harvesting.