Experimental comparison of N(1s) X-ray photoelectron spectroscopy binding energies of hard and elastic amorphous carbon nitride films with reference organic compounds

• Published in: Carbon (New York) 2003, Vol.41 (10), p.1917-1923
• Main Authors: Gammon, W.J., Kraft, O., Reilly, A.C., Holloway, B.C.
• Format: Article
• Language: English
• Subjects: A. Carbon films; B. Plasma sputtering; C. X-ray photoelectron spectroscopy; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; D. Chemical structure, Mechanical properties; Deposition by sputtering; Exact sciences and technology; Materials science; Mechanical and acoustical properties; Methods of deposition of films and coatings; film growth and epitaxy; Physical properties of thin films, nonelectronic; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/S0008-6223(03)00170-2

In this work, hard and elastic amorphous carbon nitride (a-CN x ) films were deposited by DC magnetron sputtering on heated Si(001) substrates at 400 °C. Nanoindentation results confirmed that the films were highly compliant and had high elastic recovery. X-ray photoelectron spectroscopy (XPS) was used to investigate nitrogen bonding by directly comparing the N(1s) spectra of a-CN x with the N(1s) peak positions of a variety of organic compounds that were characterized in the same XPS system. The N(1s) XPS spectra of hard and elastic a-CN x is resolved into two dominant intensity contributions at 398.5 and 400.6 eV. We show that the N(1s) spectra of a-CN x do not conclusively support a film-structure model with nitrogens bonded to sp 3 carbons. We offer an alternate interpretation based on the presented data and previous XPS, nuclear magnetic resonance (NMR), and computational work. Together, the data suggest that hard and elastic a-CN x consists of an sp 2 carbon network and that single-atom vacancy defects, as found in a graphite layer, may be present in the material. This implies that the low binding energy N(1s) component at 398.5 eV may be due to pyridine-like nitrogen bonded at the perimeter of a vacancy defect.