Silicon oxynitride as a tunable optical material

Thin disordered films of the ternary system SiO x N y with 0<x<2 and 0<y<1.33 have been sputtered reactively for optical and structural studies. Here we present structural information for these materials from EXAFS, from which it is found that the silicon oxynitride system is chemically ordered as expected. The optical tunability of this system has been determined from optical absorption, bandgap and refractive index measurements. We find that a specified bandgap with varying refractive index (or specified refractive index with tunable bandgap) is achievable within a restricted range of refractive index (or bandgap), for larger values of x and y. This conclusion from the experimental data is supported by bandgap and refractive index calculations using scaling theory.