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The production of diamond films over large areas is very promising for industrial applications. The films could be fractioned, allowing for low cost use as cutting tools, optical windows, heat dissipaters, and semiconductor devices [1,2]. A deposition method, which is relatively cheap and easy to operate and produces reasonable quality polycrystalline diamond films, is the hot filament chemical vapor deposition (HFCVD) [3]. However, it presents some disadvantages, such as the contamination of the diamond film with filament material [3], which can cause internal stresses [4]. A two-step growth method can be employed in order to improve the quality of diamond films grown by HFCVD [5]. In this work, diamond films were deposited on a Si(100) substrate having an area of 45 cm2 and a thickness of 500 mm, employing an HFCVD system. Then the sample was treated in a saturated solution of H2SO4:CrO3 and then rinsed in a (1:1) solution of H2O2:NH4OH. After this procedure, a second deposition was performed. The diamond films were characterized by Raman scattering spectroscopy (RSS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). We obtained high purity films having a thickness of 60 mm and presenting uniformity over a large area.
[1] F.X. Lu et al., Diamond Relat. Mat. 9 (2000) 1655-1659.
[2] Y. Tang, D.M. Aslam, J. Vac. Sci. Technol. B 23 (2005) 1088-1095.
[3] P.W. May, Phil. Trans. R. Soc. London A 358 (2000) 473-495.
[4] Y. Nakamura et al., Thin Solid Films 308-309 (1997) 249-253.
[5] Y. Liao et al., Thin Solid Films 368 (2000) 303-306.
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