Perspectives on emissivity measurements and modeling in silicon

A spectral emissometer operating in the wavelength range of 1-20 μm and temperature range of 30-900°C has been utilized to simultaneously measure the reflectance, transmittance and emittance of silicon. Interesting differences in the optical properties have been reported due to differences in surface morphology. Quantitative results of the effects of rough side incidence versus smooth side on the optical properties of the same silicon wafer are analyzed in this study. This analysis is based on a standard one-parameter, multiple-reflection model as extended by Vandenabeele and Maex to include effects of a roughened surface. Their modification essentially replaces the usual internal attenuation factor by an enhanced effective attenuation factor to take into account the effects of surface roughness. In the present study, it has been found that this very simple model gives a good account of the optical properties when radiation is incident on the smooth side of the wafer but fails for incidence for the roughside.