Sticking probability of CN(X 2Σ +) radicals onto amorphous carbon nitride films formed from the decomposition of BrCN induced by the microwave discharge flow of Ar

Abstract

The sticking probability, s, of CN(X 2Σ +) radicals onto amorphous carbon nitride (a-CN x ) films with high [N]/([N] + [C]) ratios (≤0.5) was evaluated. CN(X 2Σ +) radicals were generated from the decomposition of BrCN with the microwave discharge flow of Ar in the two experimental configurations, I and II, where the distance between the tip of the nozzle introducing BrCN is close (≈10 mm) to and distant (≈0.3 m) from the laser-beam path or the Si substrate, respectively. For each configuration, s was evaluated both under the desiccated and H 2O-added conditions from the number density of CN(X 2Σ +) evaluated from the intensity of the CN(A 2Π i − X 2Σ +) laser-induced fluorescence spectrum calibrated against Rayleigh scattering intensity of Ar, the flow speed measured by a time-resolved emission, and the film mass. The [N]/([N] + [C]) ratios of films were evaluated as 0.4–0.5 and 0.3 in the configurations I and II, respectively, from the compositional analysis using Rutherford back scattering and elastic recoil detection analysis together with the XPS analysis. The variation of s under various experimental conditions was discussed based on the electron densities in the reaction region and the relative density of the hydrogen-termination structures of the film surface.