<title>Attenuated total reflectance infrared absorption in CVD diamond films</title>

Abstract

The infrared absorption in microwave plasma-deposited, polycrystalline diamond films has been measured for the C-H stretch-mode and the diamond two-phonon mode, giving absorption coefficients of -26 and 7.5 cm' respectively for a 2Oun thin film, assuming that the whole thickness of the film is responsible. The C-H absorption band envelope has been deconvoluted into its various components, allowing some estimation ofthe relative importance ofCH, CH2, and CH3 groupings in the films. A significant absorption at 3 j.m due to N-H has been measured in films exposed to atomic nitrogen. 1JNFRARED ABSORPTION IN DIAMONDThe principal infrared absorptions in diamonds are due to one-phonon absorption (near lOjim), two-phonon absorption (near 5jun), and three-phonon absorption (near 3ji.m)'; in addition there are impurity-related bands in doped material (eg a 7.8un band for nitrogen)2 and C-H stretch-mode absorptions near 3.5un fordiamond grown in hydrogen 3. With the advent of "synthetic" diamond prepared by chemical vapour deposition techniques, the relative importance of these bands has changed from the domination by impurities in natural diamond to the significant C-H absorptions observed in microwave plasma deposited films .Since plasma CVD processes can produce polycrystalline diamond having no detectable incorporation of metals, nitrogen or oxygen, it is now possible to grow material in which the two-phonon and C-H absorptions are the absorption limitations for mid-JR transparency. Since the two-phonon absorption appears to be a fundamental property of the diamond lattice, the only possible improvement may be to reduce the hydrogen content of the polycrystalline diamond.2JNFRARED SPECTROMETRY 0.0200-' 0.0150-H w C-)

Structural Transformation upon Nitrogen Doping of Ultrananocrystalline Diamond Films by Microwave Plasma CVD

“…The distinctive differences between N-doped and undoped UNCD films at center are in the spectral range of 2800∼3100 cm −1 . The sp 2 -CH 2 asymmetric and sp 2 -CH stretching vibrations at 3078 cm −1 and 3039 cm −1 are observed in N-doped UNCD films [14,18,19]. The sp 3 -CH and sp 3 -CH 2 asymmetric stretching vibrations at 2895 cm −1 and 2923 cm −1 are shown for undoped UNCD films [13,14,18,19].…”

“…The sp 2 -CH 2 asymmetric and sp 2 -CH stretching vibrations at 3078 cm −1 and 3039 cm −1 are observed in N-doped UNCD films [14,18,19]. The sp 3 -CH and sp 3 -CH 2 asymmetric stretching vibrations at 2895 cm −1 and 2923 cm −1 are shown for undoped UNCD films [13,14,18,19]. We have also analyzed the ATR/FT-IR absorption spectra in the same spectral ranges as in Figure 3(b) for undoped and N-doped UNCD films at the edge position of substrate, and the results are quite similar to those at the center.…”

“…On the other hand, IR spectroscopy is known as a complementary technique to Raman scattering for the studies of structural vibrations, such as C-H bonds stretching (2750 ∼ 3300 cm −1 ) in sp 2 /sp 3 carbon-based materials [2,13]. In particular, attenuated total reflection Fourier transform infrared (ATR/FT-IR) spectroscopy is an effective technique for UNCD mirrorflat thin films samples due to the increasing optical path length by the multiple-reflected radiation in the total internal reflection element [14]. In this paper, we investigate and compare the spatial uniformity of molecular properties and surface morphology of MPCVD UNCD films processed with and without the addition of 20% nitrogen by using Raman and ATR/FT-IR spectroscopy as well as AFM for morphology images and XPS for chemical environment identifications.…”

Effect of Nano‐Ni Catalyst on the Growth and Characterization of Diamond Films by HFCVD

“…In Figure 5(a), the sp 3 -CH 2 asymmetric and symmetric vibrations at 2918 cm −1 and 2850 cm −1 are distinctively observed in CVDD-Ni diamond films. Meanwhile, the additional sp 3 -CH vibration at 2894 cm −1 is found in CVDD-NDP diamond films [20]. The incorporation of more hydrogen in CVDD-Ni diamond films may come from the catalytic dissociation of hydrogen which leads to hydrogenation of t-PA into methylene-like chains in the presence of nano-Ni, as evidenced by Raman spectra in Figure 3.…”