Raman ‘‘fingerprinting’’ of amorphous carbon films

Abstract

We compare the Raman spectra and other macroscopic properties of nearly one hundred amorphous carbon films deposited at five research laboratories by a total of five different methods in search of correlations useful for both process control and basic understanding of the structure of these materials. For the full range of carbon‐hydrogen alloys, including so‐called ‘‘amorphous diamond,’’ hydrogenated ‘‘diamondlike’’ carbon, and plasma‐polymers, a simple parametrization of the Raman spectrum in the usual 1000 cm⁻¹ to 2000 cm⁻¹ range can be used as a reliable predictor of hydrogenation and other properties (e.g., optical gap, hardness). Raman features in the 200 cm⁻¹ to 1000 cm⁻¹ range, a spectral region not usually reported for carbon films, may also be used as an indicator of hydrogenation. These growth method independent correlations greatly enhance the utility of Raman spectroscopy as a non‐destructive characterization and process control tool.