Author:

Keywords:

bias, chemical vapor deposition, molecular dynamics, nanodiamond, Raman spectroscopy, transmission electron microscopy, Science & Technology, Technology, Physical Sciences, Materials Science, Multidisciplinary, Physics, Applied, Physics, Condensed Matter, Materials Science, Physics, ENHANCED NUCLEATION, MOLECULAR-DYNAMICS, ULTRANANOCRYSTALLINE DIAMOND, FILM GROWTH, SURFACE, MECHANISM, FUNCTIONALIZATION, QUANTIFICATION, SCATTERING, HYDROGEN, 0204 Condensed Matter Physics, 0912 Materials Engineering, 1007 Nanotechnology, Applied Physics, 4016 Materials engineering, 4018 Nanotechnology, 5104 Condensed matter physics

Abstract:

In this work, a detailed structural and spectroscopic study of nanocrystalline diamond (NCD) thin films grown by a continuous bias assisted CVD growth technique is reported. This technique allows the tuning of grain size and phase purity in the deposited material. The crystalline properties of the films are characterized by SEM, TEM, EELS, and Raman spectroscopy. A clear improvement of the crystalline structure of the nanograined diamond film is observed for low negative bias voltages, while high bias voltages lead to thin films consisting of diamond grains of only ∼10 nm nanometer in size, showing remarkable similarities with so-called ultrananocrystalline diamond. These layers arecharacterized by an increasing amount of sp 2-bonded carbon content of the matrix in which the diamond grains are embedded. Classical molecular dynamics simulations support the observed experimental data, giving insight in the underlying mechanism for the observed increase in deposition rate with bias voltage. Furthermore, a high atomic concentration of hydrogen has been determined in these films. Finally, Raman scattering analyses confirm that the Raman line observed at ∼1150 cm -1 cannot be attributed to trans-poly-acetylene, which continues to be reported in literature, reassigning it to a deformation mode of CH x bonds in NCD. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.