AVS 47th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE-TuA

Paper SE-TuA5
CVD Diamond Nucleation under Extreme Conditions

Tuesday, October 3, 2000, 3:20 pm, Room 201

Session: Surface Engineering: Surface Preparation to Postcoating Surface Finishing
Presenter: K.-A. Feng, Institute of Physics, CAS, China
Authors: K.-A. Feng, Institute of Physics, CAS, China
J. Kang, University of Michigan
Z. Lin, Institute of Physics, CAS, China
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It is well known that the diamond is an outstanding material for a wide range of applications. The synthesis of the diamond films using various methods of CVD ( chemical vapor deposition) have received significant in recent years. In order to enhance the density of diamond nucleation, abrading the substrate surface with diamond paste and adding negative bias to the substrate are two routine pretreatment methods. Here, we propose a new method to greatly enhance the nuclei density. Under extreme low pressure and ultra pure hydrogen, high-density nucleation of diamond is achieved on mirror-polished silicon in a hot-filament chemical vapor deposition (HFCVD). The diamond film are studied by Scanning Electron Microscopy (SEM) and Raman Spectrum. The enhanced nucleation at very low pressure should be attributed to an increased mean free path, which induces a high density of atomic hydrogen and hydrocarbon radicals near the silicon surface. Atomic hydrogen can effectively etch the oxide layer on the surface of silicon and so greatly enhance the nucleation density. The residual oxygen in the hydrogen (not ultra pure) is shown a very obvious negative effect on the nucleation of diamond, that is, oxygen atoms possess opposite effects in the nucleation stage and the growth stage of the diamond.