Optical absorption coefficient of polycrystalline silicon with very high oxygen content

We report measurements of the room temperature optical absorption coefficient α(λ) of polycrystalline silicon ribbon material with high oxygen concentration (1.7 × 1018 at. cm−3) in the spectral range from 800 to 1200 nm. Between 800 and 1000 nm, absolute error is estimated as ≈2%. Sample to sample variations in this range are ±2%, and differences from Czochralski control samples are also within 2%. Within the experimental error, the α(λ) for our ribbon samples is indistinguishable from that of monocrystalline silicon between 800 and 1000 nm. Our data are well fitted in this region by α(λ) = (85.6/λ − 77.7)2, with λ in μm and α in cm−1. Although the experimental error rises sharply at longer wavelengths due to maximum ribbon thickness of only 450 μm, we can state that our results are consistent with the data compiled by Green [1] between 800 and 1200 nm for pure monocrystalline silicon.