Evolution of the dispersion curves of SiNxthin films. The films were produced by the N2-reactive (full symbols) and the co-sputtering (empty symbols) methods as a function of the Ar/N2 gas flow ratio and the Si/Si3N4 target power ratio, respectively. The dispersion curve of Si3N4 from  is shown for comparison.
Debieu et al. Nanoscale Research Letters 2013 8:31 doi:10.1186/1556-276X-8-31