Infrared absorption in silicon at elevated temperatures

Abstract

Isothermal electron beam heating combined with in situ optical measurements has been used to measure the temperature dependence of the spectral emissivity of lightly doped silicon in the range 345–723 °C for wavelengths between 1 and 9 μm. The absorption coefficient was deduced from the spectral emissivity and compared with the predictions of a model including phonon-assisted processes involved in interband transitions, free-carrier absorption, and lattice absorption. The experimental data agree well with the model’s results.