Incorporation of hydrogen in diamond thin films

Article history:Received 28 November 2008Received in revised form 5 March 2009Accepted 28 April 2009Available online 3 May 2009PACS:68.55.Ln82.80.Yc81.07.BcKeywords:CVD diamond filmsHydrogenGrain size dependenceERDAXPSRS In this investigation, diamond thin films with grain size ranging from 50 nm to 1 µm deposited using hotfilament chemical vapor deposition (HFCVD) have been analyzed by elastic recoil detection analysis (ERDA)for determining hydrogen concentration. Hydrogen concentration in diamond thin films increases withdecreasing grain size. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed thatpart of this hydrogen is bonded to carbon forming C–H bonding. Raman spectra also indicated the increase ofnon diamond phase with the decrease in crystallite size. Incorporation of hydrogen in the samples andincrease of hydrogencontent in nanocrystalline sample are discussed. Large separation between filament andsubstrate used for the synthesis of nanocrystalline film helped to understand the large incorporation ofhydrogen in nanocrystalline diamond films during growth. The study addresses the hydrogen trapping indifferent samples and higher hydrogen concentration in nanocrystallites by considering the synthesisconditions, growth mechanisms for different grain sized diamond films and from the quality of CVD diamondfilms.© 2009 Elsevier B.V. All rights reserved.