Emissivities of liquid and solid silicon at the melting point

The normal spectral emissivities of solid and liquid silicon at the melting point have been determined over a wavelength range between 650 and 2300 nm by the cold crucible technique. The emissivity of solid silicon was found to be greater than that of liquid silicon and the emissivities of solid and liquid silicon were found to exhibit positive and negative wavelength dependence, respectively. In the emissivity spectrum of solid silicon, no particular structure was observed around 1100 nm in wavelength (which corresponds to the band gap of 1.12 eV). The uncertainty in the emissivity value has been estimated to be less than 6%. The wavelength dependence of the emissivities suggests that electrons contributing to the covalent bond dominate the emissivity in solid silicon, whereas conduction electrons do in liquid silicon.