Investigation of local thermodynamic equilibrium of laser induced Al2O3–TiC plasma in argon by spatially resolved optical emission spectroscopy

Plasma plume of Al2O3–TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES) at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma

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