Solid-state nuclear magnetic resonance (NMR) spectroscopy is applied to the study of films from pulsed plasma enhanced chemical vapor deposition from two hydrofluorocarbon gases, CHF2CHF2 and CH2F2. Beyond confirming the relative CFx fractions obtained from X-ray photoelectron spectroscopy, NMR offered greater structural insight into the plasma film network. 19F NMR identified various network sequences, three CF3 (CF*3 C, CF*3 CF, CF*3 CF2), five CF2 (CF2CF*2CF2, CF2CF*2CF3, CF2CF*2CHF2, CF2CF2CHF*2, CFxCF*2CFx), and three CF (CF*, CH2F*, CF* = C<) segments, based on differences in next nearest neighbor attachment. 13C NMR distinguished between sp3 and sp2 bond configurations, with further separation of unsaturated nonfluorinated carbons into two distinct types. One is attributed to aromatic or graphitic carbon structures while the other is due to unsaturated carbons in closer proximity to fluorines. NMR also allowed changes in structure to be probed upon film thermal decomposition. The film from CHF2CHF2 showed both precursor desorption and CF3 detachment, while that from CH2F2 showed only CH2F loss.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry