Study of infrared absorption spectrum of diamond during growth by FTIR
College of Science, Changchun University of Science and Technology, Changchun 130022, China.Guang pu xue yu guang pu fen xi = Guang pu (Impact Factor: 0.29). 06/2008; 28(5):1049-51.
The diamond thin films were deposited on silicon substrates under invariable conditions of process pressure, substrate temperature negative direct-current (dc) bias of substrate and microwave power while the rations of methane (CH4) to hydrogen (H2) changing from 3% to 5% and 9% using electron-cyclotron-resonance microwave plasma-assisted chemical vapor deposition technique (ECRCVD). In situ Fourier transform infrared spectroscopy (FTIR) have been used to study the plasma species absorbed on the substrate surfaces as well as the species above the substrates surfaces both before and during the nucleation and film growth. It is demonstrated that these techniques can provide useful information on the early stages of diamond growth. When correlated with film properties measured by Raman spectroscopy and scanning electron microscopy, the results from FTIR indicate that the absorption of the graphitic and diamond phases are related to the ratio of CH4 to H2 and can be identified at the early stages of film growth.
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ABSTRACT: The growth mechanism and crystallization phase state were investigated by the methods of atomic force microscopy (AFM) and X-ray diffraction (XRD). The pentacene films were deposited with a self-assembling monolayer by thermal evaporation on p(+)-Si wafer substrates at room temperature and annealed at a constant temperature (80 degrees C) for 120 min. The experimental results show that pentacene films were grown with terraces island structure with the diameter of island of about 100 nm and constituted a layer consisting of faceted grains with a average step height between terraces of 1.54 nm x s(-1), which were accord with the long axis length of pentacene molecule, and the film were vertically grown on the substrate surface. The crystallization of pentacene thin films is shown in XRD pattern. The increase in the thin film thickness introduced a second set of diffraction peaks, which were attributed to the pentacene triclinic bulk phase. The critical thickness of both phases is 150 and 80 nm, respectively. At a film thickness of 150 nm, the triclinic phase diffraction peaks become the dominant phase. This is contrast to the XRD spectrum of very thin film of 80 thickness, where the thin film phase is the only contribution.
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ABSTRACT: Optical emission spectroscopy is an effective tool to measure plasma parameters and species distribution in plasma. Optical emission spectroscopy is used to measure the microwave plasma of CH4/H2 in situ. The internal radicals, the influence of methane volume fraction on radical emission intensity, and spatial distribution of the radicals and the influence of methane volume fraction on the spatial distribution in MPCVD plasma are investigated. The results show that the optical emission intensity of C2 in plasma increases with the methane volume fraction increasing obviously. Intensity ratios of CH, Hβ, Hγ to C2 reduce with increasing methane volume fraction. The spatial distributions of the radicals especially of C2 become inhomogeneous with the methane volume fraction increasing.
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