Infrared Absorption of Oxygen in Silicon

Three infrared absorption bands have been correlated with the oxygen concentration of silicon. Spectra taken between 4.2°K and 297°K show an unusual temperature-dependent fine structure in the most intense band at 1106 cm^-1. Isotopic shifts of two bands have been observed at low temperatures in samples enriched with O¹⁸. These results can be explained by a model in which interstitial oxygen is bonded to two adjacent silicon atoms in a nonlinear Si-O-Si unit. Observations on samples with different history indicate a direct but complicated dependence of some growth-dependent variables on oxygen concentration.