Contribution of CN(X2Σ+) radicals to N atoms of hydrogenated amorphous carbon nitride films formed from the microwave discharge of the gas mixture of N2 and CH3CN

Abstract

Hydrogenated amorphous carbon nitride films with the [N]/([N]+[C]) ratios of 0.24–0.33 were formed from the microwave discharge of the gas mixture of CH3CN with an excess amount of N2. The contribution of CN radicals to the N atoms of films was evaluated on the basis of the ratio of the fluxes, s=Φa-CN/ΦCN(X), where Φa-CN was the flux of N atoms incorporated into the films and ΦCN(X) that of the gas-phase CN radicals arriving onto the film surface. ΦCN(X) was obtained from the density of CN radicals evaluated by using the A2Πi–X2Σ+ laser-induced fluorescence spectra and from the flow speed by using the time-resolved emission, and Φa-CN from the film mass calibrated against the atomic compositions. The s value was in the range of 0.13–0.98, which was 1–2 times larger than the sticking probability of CN radicals, 0.19–0.45. Therefore, 50–100% of N atoms of films were identified to originate from CN radicals.