Optical behavior of reactive sputtered carbon nitride films during annealing

Abstract

The effect of annealing temperature (TA) on amorphous carbon nitride (a-CNx) thin films, deposited using radio-frequency (rf) magnetron sputtering technique of a graphite target in a pure nitrogen (N2) atmosphere at different rf power, is investigated. Film composition was analyzed using Fourier transform infrared absorption (FTIR), Raman spectroscopy, optical transmission, and photothermal deflection spectroscopy (PDS) experiments. The refractive index and the mass density were determined using optical transmission spectroscopy and elastic recoil detection analysis measurements. The microstructure analysis revealed the porous character of films, which decreases slowly with increasing annealing temperature (TA). The results of Raman spectroscopy, FTIR, and PDS experiments demonstrate that the films below 400°C mainly consist of aromatic cluster component and polymeric component. With increasing TA, the progressive graphitization of the material is accompanied by a high disorder form of Csp2 sites.