Nanostructural C-Al-N thin films studied by x-ray photoelectron spectroscopy, Raman and high-resolution transmission electron microscopy

摘要

The effects of Al incorporation and post-deposition annealing on the structural properties of C-Al-N thin films prepared by reactive unbalanced dc-magnetron sputtering were investigated using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). XPS studies demonstrated the presence of abundant Al-N bonds in addition to C-C and N-C bonds. At low incorporations of Al and N, the films were found to be essentially amorphous. By Raman and HRTEM, the formation of ～5 nm fullerene-like carbon nitride (FL-CN_x) nanostructures in an amorphous (C, CN_x matrix was evidenced with increasing Al content in the films. Crystalline improvement of FL-CN_x nanostructures was seen, as well as the precipitation of ～3-4 nm face centered cubic (fcc-) A1N nanograins by thermal annealing at 500 ℃ or above. Through these improvements, C-Al-N nanocomposite thin films were achieved. The effects of the incorporated Al and annealing on stabilizing fcc-A1N nanograins and FL-CN_x nanostructures are elucidated and explained through the use of thermodynamic considerations.