Absorption Coefficients of Crystalline Silicon at Wavelengths from 500 nm to 1000 nm

The absorption coefficient of single-crystal silicon is very important for applications in semiconductor processing and solar cells. However, large discrepancies exist in the literature about the absorption coefficient of silicon, especially in the visible and near-infrared region. Most existing review articles lack mutual comparison, and some are out of date. Due to the difficulties in accurate determination of the Si absorption coefficient in this region, additional measurements are deemed necessary. In the present study, room-temperature absorption coefficients of Si are obtained from transmittance measurements of ultrathin wafers down to thickness, at wavelengths from 500 nm to 1000 nm, using an integrating sphere and a monochromator. Furthermore, a systematic survey of available references and detailed intercomparison of existing results are performed, resulting in a critical assessment of the previous and current measurements.