Characterization of N-doped DLC Thin Films Prepared by Hydrocarbons Pyrolysis Method

Abstract

Nitrogen-doped DLC thin films prepared by a hydrocarbons pyrolysis method were characterized with Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and a four-terminal current-voltage measuring method in terms of their structural, bonding, optical and electrical properties. Raman spectra showed that doping N atoms in the DLC films caused the full width at half maximum (FWHM) values of G-peak to be broader, the G-peak positions to shift downward and the ID/IG ratio to be lower than non-doped DLC films. These indicate that N-doping to DLC induces the reduction of the sp2 based nanocluster size. The chemical bonding state of the N-doped DLC films was homogeneous in bulk, which was evaluated with XPS by Ar sputtering of the DLC films. The XPS spectra of C1s and N1s showed that the hybridized C ratio (sp3C/sp2C) of the deconvoluted C1s spectra increased due to the formation of the N bonded to sp3C (N-sp3C). In addition, the optical band gap and the resistance increased by doping N atoms in the DLC films. Our experimental results show that N-doping leads to an increase of the sp3C/sp2C and the resistance as well as the optical band gap of the DLC films prepared with the hydrocarbons pyrolysis method.