Emissivity studies on polycrystalline silicon and a-Si/SiO₂/Si

Experimental studies of the room temperature emissivity of polysilicon are reported here. These measurements have been performed using a spectral emissometer operating in the wavelength range of 0.8-20 μm. The measured optical properties are deconvoluted to yield the wavelength dependent refractive indices and extinction coefficient of polysilicon. An in house developed computer program, OPCalc, is deployed to perform these calculations. Experimental results of the temperature dependent emissivity of a-Si/SiO₂/Si/SiO₂/a-Si, fabricated on single side polished silicon substrates, in the temperature range of 300 to 1100 K have been reported here. These measurements are performed for a-Si thickness of 2100 A. Comparisons of the temperature dependent radiative properties of these structures between the front and the back show that the contribution of surface roughness to emissivity is negligible. The exposure of these a-Si coated structures to high temperatures in open environment has caused these surfaces to oxidize. Interpretations have been sought by comparisons of the experimental data with those on SiO₂/Si structures.