SUMMARY
Radiative properties studied in this work include bidirectional reflectance, spectral and directional absorptance, and emittance, in the wavelength region from ultraviolet to infrared. Since the radiative properties are demonstrated by the diffractions due to the periodicity of the structures, the diffraction efficiency of both 1D and 2D periodic structures are investigated. The lightly-doped silicon microstructures are fabricated and its diffraction at wavelength of 635 nm is studied for the transverse electric and the transverse magnetic wave incidence. The directions of diffractions are compared with theoretical predictions. Further modeling of diffraction efficiencies for periodic micro/nanostructures is studied by the rigorous coupled-wave analysis (RCWA). The RCWA is an algorithm for solving Maxwell’s equations for periodic structures, and its accuracy can be up to an arbitrary level. At wavelength between ultraviolet and near infrared, RCWA is also used to assess the validity for nanostructures of several approximate algorithms, which homogenize the periodic structures into one medium. On the other hand, with the help of the RCWA algorithm, the design of periodic micro/nanostructure with specific spectral and directional radiative properties is feasible. A design for TPV radiators is demonstrated as a kind of 1D grating, called complex gratings. Here, the complex grating is defined by its surface profile that superposes two or more 1D grating profiles. In future, RCWA will be further developed for incidence of arbitrary orientation and direction as well as the EM fields demonstration. Radiative properties of 1D nanostructures will be measured and compared with the modeling results from approximate algorithms and RCWA.