Infrared spectrum of interstitial oxygen in silicon

A stress-induced dichroism study of the 1106-cm−1 and 515-cm−1 modes of interstitial oxygen in silicon has been undertaken in order to assign the 515-cm−1 mode. It has been found that the 515-cm−1 mode is due to the symmetric stretching motion of the Si–O–Si ‘‘defect molecule’’ that has often been used to explain the vibrational spectrum of interstitial oxygen. The implications of the assignment to both the structure of the oxygen interstitial and to the characterization of oxygen concentration are discussed.