Optical absorption in plasma-deposited silicon oxynitride films

Abstract

We present an experimental and theoretical study of the optical absorption of amorphous silicon oxynitride films. The optical absorption coefficient α in the energy range from 4 to 10 eV has been measured for SiOxNyHz films between the nitride and oxide compositions grown by plasma-enhanced chemical vapor deposition. We have also calculated the coefficient α for SiOxNy alloys assuming a random mixture of Si—N and Si—O bonds within the disordered alloy. The variation of the optical gap Eg with the composition and the appearance of steps in the optical absorption for oxygen-rich samples are discussed.