Analysis of localized vibration of nitrogen in silicon

Normal modes of local vibration of nitrogen in CZ silicon are analyzed by using the molecular orbital calculation. Wavenumber and dipole are compared to the observed infrared absorption spectra. It is confirmed that the observed peaks at 963 and 764 cm−1 are due to a normal vibration mode of antisymmetric stretch of BF3-type planar four-atom molecule and H2O-type nonlinear three-atom molecule, respectively. Those modes in the N–N–O structure and N–N–O–O structure were identified and the 1026 cm−1 peak was assigned to the Si–O–Si vibration. The results help to establish the total nitrogen concentration in CZ-Si.