Infrared Absorption and Oxygen Content in Silicon and Germanium

An optical absorption band at 9μ has been correlated with the oxygen content in silicon. Pulled silicon crystals were found to contain up to ${10}^{18}$ oxygen atoms per ${\mathrm{cm}}^3$ which seem to originate from the quartz crucible. The oxygen concentration in silicon crystals prepared by the floating zone technique in vacuum was found to be less than ${10}^{16}$ oxygen atoms per ${\mathrm{cm}}^3$. The 9μ absorption due to silicon-oxygen bond stretching vibrations provides a possibility for a quantitative oxygen analysis of high sensitivity. A corresponding absorption in germanium at 11.6μ is believed to be due to a germanium-oxygen vibration.