Effect of the analytic regions on the quality trend of diamond-like/ graphitic carbon ratios in raman spectra

Abstract

Raman spectroscopy is a useful and non-destructive tool for the structural characterization of diamond-like carbon (DLC) films. Even though Raman spectroscopy is not a quantitative technique, the area integral intensity ratio of D and G peaks (ID/IG) derived by the fitting of separate Gaussian curves usually serves as an indicator of the quality trend of diamond-like material. However, conflicting reports still exist on the diamond-like films analyzed by the fitting method of Raman spectra. In this work we show that the quality trend of the diamond-like/graphitic carbon ratio is critically dependent upon the boundary conditions of the analytic regions. We also examine the possibility of directly applying the peak height ratio H D/HG as an alternative method to analyze Raman spectra. The method based on peak height ratios (HD/HG), and an established method using ID/IG ratios can give similar results depending on the choice, in the latter method, of the boundary conditions used for integration. However, the method based on the determination of peak heights avoids the arbitrary assignment of integral boundary conditions while additionally generating a data set that shows statistically smaller standard deviations than the commonly used integration method. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen.