Origin of visible photoluminescence from Si-rich and N-rich silicon nitride films

Si-rich (SiN1.1) and N-rich (SiN1.5) silicon nitride films were grown on the Si wafers by plasma-enhanced chemical vapor deposition. Their composition and structure were investigated by Rutherford backscattering spectroscopy and transmission electron microscopy. The effect of composition and post-deposition annealing temperature on the SiNx light-emitting properties was investigated by the examination of photoluminescence. The intensive bands for the Si-rich and N-rich nitride films were detected in the red and blue spectral ranges, respectively. Photoluminescence bands transformations for the annealed nitride films can be ascribed to the increasing K- and N-centre concentration via the SiH and NH bonds rupture and the competitive processes of defect annihilation. On the basis of photoluminescence band FWHM broadening with “x” increasing, the FWHM dependence on the measurement temperature and SiNx films inhomogeneous structure, the emission from the SiN1.1 and SiN1.5 films is attributed to the transitions between the bands of defect and tail states associated with chemical disordering.