Ultraviolet Raman spectroscopy characterizes chemical vapor deposition diamond film growth and oxidation

Abstract

The Raman spectra of diamond and chemical-vapor-deposition (CVD) diamond films in the UV have been excited within the diamond band gap at 228.9 nm for the first time. The lack of fluorescence in the UV-excited Raman spectrum of diamond and CVD diamond films allows Raman spectroscopy to monitor the carbon-hydrogen (C-H) stretching vibrations of the nondiamond components of the CVD film as well as the third-order phonon bands of diamond. The relative intensity of the C-H stretching bands at-2930 cm-' to the diamond first-order phonon band at 1332 cm-' is proportional to the atomic fraction of covalently bound hydrogen in the CVD diamond film. The third-order phonon band intensity and frequency maxima are very sensitive to the size of the diamond crystallite. Its intensity decreases, and the maximum shifts to lower frequency as the size of the diamond crystallite decreases. It is shown here that UV Raman diamond measurements have significantly greater information content than visible Raman measurements.

The Electrochemical Properties of Nanocrystalline Diamond Thin‐Films Deposited from C 60 /Argon and Methane/Nitrogen Gas Mixtures

“…These``amorphous carbon bands'' in the nanocrystalline diamond spectra result from the sp 2 -bonded carbon in the grain boundaries. It is well known that the relative intensities of the sp 2 and sp 3 carbon Raman and emission spectral features depend on the grain size [29], ®lm stress [30,31], and excitation wavelength [21,29]. Raman spectroscopy using UV excitation has been shown to provide reliable characterization data of nanocrystalline diamond [21,22].…”

Micro‐Raman Studies on DLC coatings

“…In the C-H stretching region hydrogen bound to both sp 3 carbon (~2900 cm ±1 ) and sp 2 carbon (~3100 cm ±1 ) has been observed in the Raman spectra. [68] Additional elements such as nitrogen, silicon, boron, fluorine, phosphorus and various metals have been introduced in the carbonaceous structure to modify the properties of conventional DLC coatings, in particular hardness, friction, wear, biocompatibility, optical and electrical characteristics.…”

UV Raman spectroscopy of segregated carbon in silicon oxycarbides

“…1. UV Raman spectra of SiOC/C (¯1 vol.%), SiC, HOPG 29) and nanodiamond. Spectra are offset for clarity.…”

“…A much narrower G peak is seen in the spectrum of highly ordererd pyrolytic graphite (HOPG). 29) Note that graphite shows no D mode (1380 cm…”