Precursor of N atoms of hydrogenated amorphous carbon nitride films formed from the microwave discharge of C2H2/N2 gas mixture

Abstract

Hydrogenated amorphous carbon nitride films with the [N]/([N] + [C]) ratios of 0.29–0.44 were formed from the microwave discharge of the gas mixture of C2H2 with an excess amount of N2. The ratio of the fluxes, s = Φa-CN/ΦCN(X), was evaluated in this study, where Φa-CN was the flux of N atoms incorporated into the films and ΦCN(X) was that of CN radicals in the gas phase. ΦCN(X) was evaluated from the density of CN radicals using the A2Πi–X2Σ+ laser-induced fluorescence spectra and from the flow speed using the time-resolved emission, and Φa-CN from the film mass calibrated against atomic compositions. The s value was in the range of 0.22–0.78, being 1.2–1.7 times the sticking probability of CN radicals corrected in this study, 0.19–0.45. Then, the contribution of CN radicals was evaluated to be 60–80% of the N source of the films. The chemical structure and mechanical property of the films were analyzed in terms of Raman scattering, IR absorption, and nanoindentation measurements.