Spectral and thermal properties of tungsten selective emitters with rectangular microcavities for thermophotovoltaic generations

Spectral properties of 2D W surface gratings are investigated by numerical calculations based on rigorous coupled-wave analysis to obtain a good spectral selectivity enough to use as a selective emitter for thermophotovoltaic generations. To demonstrate the calculated results, a 2D grating with 1.0 /spl mu/m periodicity composed of rectangular microcavities is fabricated on a single crystalline W substrate by electron beam lithography and fast atom beam etching techniques. This grating shows high emissivity in the NlR region corresponding to the spectral response of GaSb PV cells. It is also found that spectral emissivity of emitters is considerably dependent on temperature. A theoretical analysis is conducted to evaluate the temperature dependence of spectral emissivity of metallic microstructured selective emitters in the frame of the Drude theory.