Structural properties and surface morphology of laser-deposited amorphous carbon and carbon nitride films

• Published in: Surface & coatings technology 2000-03, Vol.125 (1-3), p.124-128
• Main Authors: Riedo, E., Comin, F., Chevrier, J., Schmithusen, F., Decossas, S., Sancrotti, M.
• Format: Article
• Language: English
• Subjects: AFM; CNx films; Cross-disciplinary physics: materials science; rheology; Diamond-like carbon films; EELS; Exact sciences and technology; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Pulsed laser deposition; XPS
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/S0257-8972(99)00591-5

A study of the relationship between structure and growth parameters for existing and candidate carbon-based protective coatings has been carried out. In particular, diamond-like carbon (DLC) and carbon nitride thin films were deposited on silicon wafers by pulsed Nd:YAG laser (wavelength 532nm) ablation of graphite in high vacuum (p=1.5×10−7Pa) and in a nitrogen atmosphere (p=13Pa). The composition (N/C ratio), the structural and electronic properties and the surface morphology of the deposited films were investigated as a function of laser fluence (1–12J/cm2). The highest N/C ratio 0.40 was obtained with a laser fluence of 12J/cm2; for this nitrogen concentration X-ray photoelectron spectroscopy (XPS) reveals an increase of CN bonds instead of CN bonds with respect to lower concentrations. Electron energy loss spectroscopy (EELS) and XPS show an increase of sp2 carbon bonded sites in the DLC films deposited with lower laser fluences in agreement with the theory of the so-called sub-implantation model. EELS also reveals a gradient in the chemical nature of the films through the thickness. Atomic force microscopy analysis shows that the root-mean-squared roughness of the DLC samples is about 3Å over the laser fluence range investigated.