Synthesis of nanocrystalline diamond by the direct ion beam deposition method
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Synthesis of nanocrystalline diamond by the direct ion beam deposition method X.S. Sun, N. Wang, W.J. Zhang, H.K. Woo, X.D. Han, I. Bello, C.S. Lee, and S.T. Leea) Center of Super-Diamond and Advanced Films, Department of Physics & Materials Science, City University of Hong Kong, Hong Kong (Received 13 August 1998; accepted 14 June 1999)
Nanocrystalline diamond has been synthesized on a mirror-polished Si(001) substrate by means of direct ion beam deposition. Low-energy (80–200 eV) hydrocarbon and hydrogen ions, generated in a Kaufman ion source, were used to bombard the substrates. The bombarded samples were characterized by high-resolution transmission electron microscopy and Raman spectroscopy. Nanocrystalline diamond particles of random orientation were observed in a matrix of amorphous carbon film on the Si(001) substrate. The size of the nanocrystalline diamond particles varied in the range of 50–300 Å. The mechanism of ion-induced formation of nanocrystalline diamond is discussed.
Recently, important progress toward large-area heteroepitaxial diamond using chemical vapor deposition (CVD) has been achieved. By combination of a biasenhanced nucleation (BEN) technique1–3 with subsequent CVD growth, oriented diamond films have been deposited.4,5 The biasing treatment of substrate has not been recognized as an established method for enhancing nucleation to deposit oriented diamond film on a nondiamond substrate. The mechanism of BEN is, however, not clearly understood to date. From previous experimental results,6,7 it is known that substrate biasing leads to extraction of ion species from the plasma and accelerates the ions toward the substrate to form ion bombardment. Energetic ion bombardment is proposed to play a key role in the nucleation process,8 but how ion bombardment works on the nucleation enhancement has not been clearly identified. From the technique point of view, the ion beam technique is the most direct method to study the effect of ion bombardment. In general, the advantage of ion beam technique is the controllability of the energies and fluences of the ions incident on the growing surface. The ion beam deposition technique also allows independent variation of the ion species, ion energy, and current density of the ion beam and the substrate temperature. In fact, many attempts have been made in the deposition of diamond by means of ion implantation and mass-selected ion beam method. Among the various homogrowths of diamond,9–11 Lee et al.11 recently reported that mediumenergy (5–25 keV) carbon ion implantation into diamond substrates led to the growth of polycrystalline diamond a)
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J. Mater. Res., Vol. 14, No. 8, Aug 1999 Downloaded: 18 Mar 2015
with a very high density of extended defects. For the heterosubstrates, many attempts of using carbon ion implantation have also been made;12–15 however, no definitive evidence was obtained for the f
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