Hydrogen quantification in hydrogenated amorphous carbon films by infrared, Raman, and x-ray absorption near edge spectroscopies

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DC substrate bias effects on the physical properties of hydrogenated amorphous carbon films grown by plasma-assisted chemical vapour deposition

Hydrogenated amorphous carbon (a-C:H) films have been grown from argon/methane gas mixtures by electron cyclotron resonance chemical vapour deposition (ECR-CVD) on silicon substrates. The effects of the application of a DC substrate bias on the structural, morphological and mechanical properties of the films have been explored by multiple analysis techniques such as infrared and micro-Raman spectroscopy, atomic force microscopy, nanoindentation and pin-on-disk wear testing. In general, within the range of applied substrate bias (i.e. from -300 up to + 100V) we have observed a strong correlation between all measured properties of the a-C:H films and the ion energy. This work shows that the properties can differ greatly and indicates a threshold energy in the order of 90 eV. For the production of hard, low-friction coatings energies above this value are required. (C) 2007 Published by Elsevier Ltd.status: publishe

Hydrogen quantification in hydrogenated amorphous carbon films by infrared, Raman, and x-ray absorption near edge spectroscopies

In this study, we have employed infrared (IR) absorption spectroscopy, visible Raman spectroscopy, and x-ray absorption near edge structure (XANES) to quantify the hydrogen (HI) content in hydrogenated amorphous carbon (a-C: HI) films. a-C: H films with a hydrogen content varying from 29 to 47 at. % have been synthesized by electron cyclotron resonance chemical vapor deposition at low substrate temperatures (< 120 degrees C) applying a wide range of bias voltage, V-b, (- 300 V < V-b < + 100 V). With the application of high negative V-b, the a-C: II films undergo a dehydrogenation process accompanied by a sharp structural modification from polymer-to fullerenelike films. The trend in the H content derived from elastic recoil detection analysis (ERDA) is quantitatively reproduced from the intensity of the C-H bands and states in the IR and XANES spectra, respectively, as well as from the photoluminescence (PL) background drop in the Raman spectra. Using the H contents obtained by ERDA as reference data, semiquantitative expressions are inferred for the amount of bonded hydrogen as a function of the experimental spectroscopic parameters, i.e., the integrated area of the IR C-H stretching band at about 2900 cm(-1), the PL background in visible Raman spectra, and the XANES intensity of the sigma*-CH peak. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3103326]status: publishe

TiNxOy/TiN dielectric contrasts obtained by ion implantation of O+2 ; structural, optical and electrical properties

The properties of TiN can be gradually transformed by O+2 implantations in the 10–40 keV range and fluences in the 5 × 1013–5 × 1016 cm−2 range. The resulting structure consists of shallow TiNxOy(TiNO)/TiN contrasts with increased resistivity on the top layer. In fact, oxygen actively replaces nitrogen in the implanted TiN region as illustrated by Rutherford backscattering spectrometry. N substitutions and vacancies in the lattice induce structural distortions and strain generation as illustrated by x-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy. The influence of these modifications in the optical and electrical properties was characterized by spectroscopic ellipsometry and four probe resistivity measurements. The proposed process, especially at the lower energy, is liable to help in the creation of electrical/photonic structures based in shallow TiNO/TiN electric/dielectric contrasts.JRC.DG.I.5-Nanobioscience

Direct observation of waveguide formation in KGd(WO4)2 by low dose H+ ion implantation

In this letter, a direct measurement of a refractive index change in potassium gadolinium tungstate (KGW) created by a low-dose ion implantation of 1\u2004MeV hydrogen ions is reported. The characterization was performed using both microreflectivity and Raman spectroscopy measurements. The microreflectivity results show both negative and positive changes in refractive index in the damage region when measuring refractive index along different polarization axes. Micro-Raman spectroscopy analysis shows preservation of the Raman characteristics of KGW in the nondamaged crystal regions. These results show that ion implantation in KGW has a great potential for fabricating waveguide structures in Raman-based photonic devices.Peer reviewed: YesNRC publication: Ye