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Ambrosone G.,CNR Institute of Neuroscience | Ambrosone G.,University of Naples Federico II | Basa D.K.,Utkal University | Coscia U.,University of Naples Federico II | And 3 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2011

Silicon rich hydrogenated amorphous silicon-carbon alloy films were deposited by plasma enhanced chemical vapour deposition in low power regime from silane methane mixtures diluted in helium by varying the methane fraction between 0.4 and 0.8. Films with carbon content ranging from 0.06 to 0.28 were obtained with a deposition rate of about 0.1 nm/s. The influence of carbon incorporation on the optical properties as well as disorder and defect density of the films has been investigated. The increase in carbon content leads to a decrease of the refractive index and an increase of the optical gap and disorder in the films. The defect density also increases with increasing carbon content, however lower values than those of films deposited by undiluted silane methane mixtures have been obtained for a carbon content greater than 0.1. Finally, the enhancement of carbon content causes the shift of peak position as well as the increase in the intensity and the width of the photoluminescence spectra. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Coscia U.,University of Naples Federico II | Coscia U.,Complesso Universitario | Ambrosone G.,University of Naples Federico II | Ambrosone G.,CNR Institute of Neuroscience | And 4 more authors.
Thin Solid Films | Year: 2013

Nanostructured silicon carbon thin films, composed of Si nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix, have been prepared by varying rf power in ultra high vacuum plasma enhanced chemical vapour deposition system using silane and methane gas mixtures diluted in hydrogen. In this paper we have studied the compositional, structural and electrical properties of these films as a function of rf power. It is shown that with increasing rf power the atomic densities of carbon and hydrogen increase while the atomic density of silicon decreases, resulting in a reduction in the mass density. Further, it is demonstrated that carbon is incorporated into amorphous matrix and it is mainly bonded to silicon. The study has also revealed that the crystalline volume fraction decreases with increase in rf power and that the films deposited with low rf power have a size distribution of large and small crystallites while the films deposited with relatively high power have only small crystallites. Finally, the enhanced transport properties of the nanostructured silicon carbon films, as compared to amorphous counterpart, have been attributed to the presence of Si nanocrystallites. © 2013 Elsevier B.V. Source


Basa D.K.,Utkal University | Abbate G.,University of Naples Federico II | Abbate G.,CNR Institute of Neuroscience | Ambrosone G.,University of Naples Federico II | And 5 more authors.
Journal of Applied Physics | Year: 2010

The optical properties of the hydrogenated amorphous silicon carbon alloy films, prepared by plasma enhanced chemical vapor deposition technique from silane and methane gas mixture diluted in helium, have been investigated using variable angle spectroscopic ellipsometry in the photon energy range from 0.73 to 4.59 eV. Tauc-Lorentz model has been employed for the analysis of the optical spectra and it has been demonstrated that the model parameters are correlated with the carbon content as well as to the structural properties of the studied films. © 2010 American Institute of Physics. Source


Ambrosone G.,CNR Institute of Neuroscience | Ambrosone G.,University of Naples Federico II | Basa D.K.,Utkal University | Coscia U.,University of Naples Federico II | And 2 more authors.
Thin Solid Films | Year: 2010

Hydrogenated amorphous silicon carbon alloy films of different carbon content were prepared by Plasma Enhanced Chemical Vapor Deposition using silane and methane with helium dilution and were characterized to study their opto-electronic, structural and defective properties. A linear correlation between micro structural disorder and overall disorder has been demonstrated. Further, it has been shown that the increase in the intrinsic disorder leads to an increase in the defect density while the increase in voids results in the decrease in the mass density for the studied films. © 2010 Elsevier B.V. All rights reserved. Source


Ambrosone G.,CNR Institute of Neuroscience | Ambrosone G.,University of Naples Federico II | Basa D.K.,Utkal University | Coscia U.,University of Naples Federico II | And 2 more authors.
Thin Solid Films | Year: 2012

Nanostructured silicon carbon films composed of silicon nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix have been deposited by plasma enhanced chemical vapour deposition technique using silane and methane gas mixture highly diluted in hydrogen. The structural and optical properties of the films have been investigated by X-ray diffraction, Raman, Fourier transform infrared, ultra violet-visible-near infrared and photoluminescence spectroscopies while the composition of the films has been obtained from nuclear techniques. The study has demonstrated that the structure of the films evolves from microcrystalline to nanocrystalline phase with the increase in radio frequency (rf) power. Further, it is shown that with increasing the rf power the size of silicon nanocrystallites decreases while the optical gap increases and a blueshift of visible room temperature photoluminescence peak can be observed. © 2012 Elsevier B.V. All rights reserved. Source

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