Effect of Nitrogen Plasma Afterglow on Amorphous Carbon Nitride Thin Films Deposited by Laser Ablation

By employing pulsed laser deposition, amorphous carbon nitride $(a-CN_{x})$ thin films, were prepared on unheated Si (100). Investigation of compositional and structural modifications induced by microwave nitrogen plasma afterglow on amorphous carbon nitride thin films, has been carried out in the range of nitrogen pressure 10-1000 Pa. The role of nitrogen plasma afterglow on the physicochemical and structural characteristics of a-$CN_{x}$ was explored using the diagnostic techniques: Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Upon analyzing the Raman and X-ray photoelectron spectra, it is concluded that employing nitrogen plasma afterglow during the films deposition favors, in general, the increase in nitrogen content and the formation of $sp^2$ bonding in the a-$CN_{x}$ films. The analysis of scanning electron and atomic force microscopy images demonstrated that the films had a granular structure formed from particles coalesced together into cauliflower-like clusters and the particles size increased by increasing nitrogen pressure. A 2D atomic force microscopy line profile measurements provide evidence to a decrease in size of clusters using nitrogen plasma afterglow which could be due to the annihilation of excess vacancies and/or the elimination of grain boundaries. These analyses were found to be quite reliable to help understand the effects of microwave nitrogen plasma afterglow on amorphous carbon nitride thin films.