P. Azadfar

Islamic Azad University, Teheran, Tehrān, Iran

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Publications (4)6.34 Total impact

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    ABSTRACT: Boron-doped diamond nanocrystals were grown on Si wafers through introduction of the gas mixture of B2O3 dissolved in ethanol and hydrogen by a hot filament chemical vapor deposition (HFCVD) technique. Boron level in diamond films were controlled in the range from 100 to 500 ppm by adjusting the B/C ratios of gas mixtures in order to synthesize and improve the conductivity and quality of HFCVD diamond films with cluster size of nanometer. To investigate the effect of different boron percentage in the chamber on deposited films, Raman spectroscopy, field emission scanning electron microscopy and four point probe techniques were applied to characterize the properties of diamond films. Experimental results indicated that higher boron incorporation in the diamond films introduced bigger crystal clusters, better crystal quality and smaller film resistivity when the level of boron increased from 100 to 300 ppm, while they showed an opposite trend with a further increase of boron level from 300 to 500 ppm. However, in any case the higher boron-doping level led to a decrease of the non-diamond phase in the nanodiamond films.
    No preview · Article · Apr 2015 · Journal of Crystal Growth
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    ABSTRACT: In this study, diamond films were synthesized on directed Si and improved nucleation nano-iron layer Si substrates using B2O3 in ethanol and hydrogen gas mixture by hot filament chemical vapor deposition method. To investigate the role of catalyst in purity, cluster size, growth rate and conductivity of grown boron-doped films, the boron to carbon ratio was constant. Raman spectroscopy, field emission scanning electron microscopy and four point probe techniques were applied to characterize the properties of films. It was found that nano-iron layer leads to deposit boron-doped diamond film with better structural quality as well as more effective boron doping concentration. This rising in the conductivity of the grown film on Fe-coated substrate can be mainly attributed to the catalytic activity of iron to increase the diamond cluster size as well as reduce the formation of pores and amorphous phases. Moreover, a 25 % increase in film thickness assisted by iron-catalyst was observed.
    No preview · Article · Mar 2015 · Journal of Inorganic and Organometallic Polymers and Materials
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    ABSTRACT: Carbon dioxide ions with 29keV energy were implanted into (400) high-purity p-type silicon wafers at nearly room temperature and doses in the range between 1×1016 and 3×1018ions/cm2. X-ray diffraction analysis (XRD) was used to characterize the formation of SiC in implanted Si substrate. The formation of SiC and its crystalline structure obtained from above mentioned technique. Topographical changes induced on silicon surface, grains and evaluation of them at different doses observed by atomic force microscopy (AFM). Infrared reflectance (IR) and Raman scattering measurements were used to reconfirm the formation of SiC in implanted Si substrate. The electrical properties of implanted samples measured by four point probe technique. The results show that implantation of carbon dioxide ions directly leads to formation of 15R-SiC. By increasing the implantation dose a significant changes were also observed on roughness and sheet resistivity properties.
    Full-text · Article · Dec 2008 · Applied Surface Science
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    ABSTRACT: In this work the surface of (4 0 0) p-type Si wafers is bombarded with 29 keV nitrogen ions at various ion beam fluency varied from 10$^{16}$ to 10$^{18}$ ions/cm$^2$ and the results are investigated. Si$_3$N$_4$ film with orthorhombic structure is formed on silicon surface with cubic structure while the lattice parameter of the generated layer is not affected by change of nitrogen ion beam dose. RMS roughness of implanted samples increases by increasing the nitrogen dose, specially when the dose is more than 3$\times$10$^{17}$ ions/cm$^2$. Surface resistivity of samples is increased by increasing the dose of ion beam. Although changes in the transmission of implanted samples does not differ very much in comparison with row sample but reflection of implanted samples decrease about 60% for the electromagnetic wave in the range of 200 to 1500 nm. Absorption coefficient of samples is obtained and the band gap energy of samples is calculated. It is observed that formation of defect levels changes the magnitude of band gap energy.
    Full-text · Article · May 2008 · The European Physical Journal Applied Physics

Publication Stats

7 Citations
6.34 Total Impact Points


  • 2015
    • Islamic Azad University
      • Plasma Physics Research Centre (PPRC)
      Teheran, Tehrān, Iran
  • 2008
    • Islamic Azad University Karaj Branch
      Leredi, Alborz, Iran