Determination of stoichiometry and oxygen content in platelike and octahedral oxygen precipitates in silicon with FT-IR spectroscopy

p-and n-type Si wafers with interstitial oxygen concentrations in the range of (9-11)x10(17) cm(-3) were subjected to different thermal treatments. FT-IR measurements were performed at 300K and 6K. The absorption spectra of octahedral and platelet precipitates can be reconstructed well by the theory of absorption of light by small particles. An empirical relationship is deduced to determine the concentration of oxygen in both types of precipitates, with an estimated accuracy of 15%. Analysis of the spectra leads to the conclusion of an oxygen density of 3x10(22) cm(-3) and identification bf the precipitates as consisting of SiO, which can be modeled as a mixture of SiO2 and a-Si.