P. Ghosh

Jadavpur University, Kolkata, Bengal, India

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Publications (37)53.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Thin amorphous diamond-like nanocomposite (a-DLN) films are deposited on p- type crystalline silicon (c-Si) by plasma assisted chemical vapour deposition (PACVD) technique to use it as an ammonia (NH 3) gas sensor operable at room temperature. The non-linear current–voltage (I–V) characteristic of a-DLN/c-Si heterojunction shows a very good rectifying property of the junction in air and quick sensitivity in NH 3 gas at room temperature. The current output in reverse biased condition of the a-DLN/c-Si ...
    Physics of Semiconductor Devices, 01/2014: chapter MEMES and SENSOR: pages 479-482; Springer International Publishing.
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    ABSTRACT: Silicon nanowire (SiNW) arrays were synthesized using single step metal assisted chemical etching (SSMACE) method on n-type mono crystalline silicon. The effect of encapsulation of SiNW arrays with diamond-like nanocomposite (DLN) deposited by plasma assisted chemical vapor deposition (PACVD) method has been investigated. The structural and optical properties of SiNW and DLN thin film has been studied using FESEM, FTIR and UV–VIS-NIR spectroscopy. A very low (3–4 %) and high broadband (300–1,000 nm) reflection has been achieved from SiNWs array. However, after deposition of DLN thin film on nanowire array, the reflection further reduces significantly to 1.7 %. The SiNW arrays encapsulated with DLN thin film has a great potential to use in solar cell.
    Physics of Semiconductor Devices, Edited by V. K. Jain vkjain@amity.edu (4) Abhishek Verma, 01/2014: chapter Environmental Science and Engineering: pages 327-330; Springer International Publishing., ISBN: 978-3-319-03002-9
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    ABSTRACT: Thin amorphous diamond-like nanocomposite (a-DLN) films are deposited on p-type crystalline silicon (c-Si) by plasma assisted chemical vapour deposition (PACVD) technique to use it as an ammonia (NH3) gas sensor operable at room temperature. The non-linear current–voltage (I–V) characteristic of a-DLN/c-Si heterojunction shows a very good rectifying property of the junction in air and quick sensitivity in NH3 gas at room temperature. The current output in reverse biased condition of the a-DLN/c-Si heterojunction is ~ 15 times higher in NH3 than in air. Sensor also shows a good recovery property to the original state, even at room temperature. Sensing material is characterized by using Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV–VIS Near-IR Spectroscopy, to understand the sensing behaviour.
    International Conference on Physics of Semiconductor Devices, India; 12/2013
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    P. K. Ghosh, K. K. Chattopadhyay
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    ABSTRACT: Nanoparticles of ZnS have been synthesized via radio frequency magnetron sputtering technique. Selected area electron diffraction patterns confirmed the nanocrystalline cubic phase of ZnS. TEM micrographs of the thin films revealed the manifestation of ZnS nanoparticles (3.00 - 5.83 nm). UV-VIS-NIR spectrophotometric measurements showed that the films are highly transparent ~ 90 % with a blue shift of absorption edge. The particle size calculated from the shift of direct bandgap (3.89-4.44 eV) due to quantum confinement of nanoparticles lying in the range 3.23 - 5.60 nm, which well support the TEM results. The photoluminescence spectra of the films showed sulfer vacancy in the films and the EDX results also supported these results.
    06/2013;
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    ABSTRACT: We are presenting the feasibility study on the industrial solar cell processing with n-type crystalline silicon. For the performing feasibility study, we have introduced SWOT (strength-Weakness-Opportunities, & Threat) analysis of crystalline solar cell with n-type crystalline silicon. Cost comparison of crystalline silicon p-type wafer and n-type wafer has also been given in this paper for better understanding the cost benefit of the total integrated crystalline silicon production line. An additional motivation for highlighting of already existing industrial process sequence for n-type silicon is incorporating in this paper.
    IOSR Journal of Engineering. 07/2012; 2(7):2250-3021.
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    ABSTRACT: Nanocrystalline cadmium sulfide thin films were deposited by the radio frequency magnetron sputtering technique on Si and glass substrates with different particle sizes and thicknesses by varying deposition time. X-ray diffraction and transmission electron microscopic studies confirmed the nanocrystalline cubic CdS phase formation. TEM micrographs of the films revealed the manifestation of nano-CdS phase with average particle size of 3.6–7.3 nm for different films. These nanocrystalline films were analyzed by spectroscopic ellipsometry. The optical constants and the fitting constants were obtained by fitting the ellipsometric parameter del and psi data using Forouhi and Bloomer models in the wavelength range 248–825 nm. The optical band gaps of the films were also measured by spectrophotometric studies. It was found that the energy band gap decreased from 3.28 to 2.54 eV when the film thickness increased from 153 to 205 nm.
    Physica E Low-dimensional Systems and Nanostructures 06/2010; 42(8):2097–2102. · 1.52 Impact Factor
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    ABSTRACT: The electrical transport properties of hydroiodic acid doped polyaniline in the temperature range 77 ≤ T ≤ 300 K were studied. The magnetic field strength was varied to a maximum of 1T in the frequency range of 20 Hz–1 MHz. The ac conductivity followed the universal dielectric response σ′(f) ∞ fs. The trend in the variation of ‘s’, the temperature dependence of the frequency exponent, indicated that correlated barrier hopping is the dominating charge transport mechanism. The ac conductivity also shows a positive variation with magnetic field, which can be interpreted by Maxwell-Wagner capacitor model. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
    Polymer Engineering and Science 03/2009; 49(5):910 - 915. · 1.24 Impact Factor
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    ABSTRACT: We investigated the electrical-transport properties of hydroiodic acid doped polyaniline in the temperature range 77–300 K, applying magnetic field strength to a maximum of 1 T in the frequency range 20 Hz–1 MHz. The direct-current conductivity was explained by variable range hopping theory, and the direct-current magnetoconductivity, which was positive, was interpreted by orbital magnetoconductivity theory. The alternating-current (ac) conductivity was found to follow the universal dielectric response σ′(f) ∝ fs, where σ′(f) is the frequency-dependent real part of the complex ac conductivity, f is the frequency, and s is the frequency exponent. The trend in the variation of s, the temperature dependence of the frequency exponent, corroborated the fact that the correlated barrier hopping was the dominating charge-transport mechanism. The ac conductivity also showed a positive variation with magnetic field, which could be interpreted by this theory. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
    Journal of Applied Polymer Science 02/2008; 108(4):2312 - 2320. · 1.40 Impact Factor
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    ABSTRACT: Nanocrystallites of cadmium sulfide (CdS) thin films have been deposited by radio frequency magnetron sputtering technique. XRD and TEM diffraction patterns have confirmed the nanocrystalline cubic CdS phase formation. The intensity of XRD peaks also increases with the increase of deposition time that implies that better crystallinity takes place at higher deposition time. TEM micrographs of the films have revealed the manifestation of nano CdS phase with average particle size lying in the range 2.00 nm to 5.36 nm. UV-VIS spectrophotometric measurement showed high transparency of the film with a blue-shift of the absorption edge. The direct optical bandgap values of the films increased with the increase of deposition time and lie in the range from 3.06 - 3.94 eV.
    Physics of Semiconductor Devices, 2007. IWPSD 2007. International Workshop on; 01/2008
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    ABSTRACT: Ni nanoclusters in silica matrix have been synthesized via sol–gel process for different percentage of Ni in the matrix. Transmission electron microscopic studies showed that the particle size of nickel was in the range 6–8.5nm for a variation of Ni content in the silica matrix 5–15%. Selected area electron diffraction patterns confirmed that these nanoparticles are cubic Ni and XRD studies of the composite powder also supported the presence of metallic Ni. It was observed that with the increase of nickel percentage in the silica matrix, the particle size increased, and stress decreased. ac conductivity, dielectric constant and complex permittivity spectrum have been studied over a wide range of frequency for different percentage of Ni content in the samples at room temperature. ac conductivity (σac) measurements indicated σac increased in the lower frequency region (below 12–14kHz), but becomes nearly constant in the high frequency range. In the Cole–Cole plot two semicircular arcs appeared which indicated polydispersive nature of the dielectric properties of the Ni–silica nanocomposite. It was also observed that the dielectric properties of the Ni–silica nanocomposite not only depended on frequency but also changes with the grain size.
    Journal of Alloys and Compounds 01/2008; 453(1):1-6. · 2.73 Impact Factor
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    ABSTRACT: Nanoparticles of ZnS:Mn have been grown by radio frequency magnetron sputtering technique on glass and Si substrates at a substrate temperature 300 K. X-ray diffraction patterns and selected area electron diffraction patterns confirmed the nanocrystalline cubic ZnS phase formation. TEM micrographs of the films revealed the manifestation of ZnS:Mn nanoparticles with an average size ∼6 nm. UV–Vis–NIR spectrophotometric measurement showed that the films are highly transparent (∼90%) in the wavelength range 400–2600 nm. From the measurements of transmittance spectra of the films the direct allowed bandgap values have been calculated and they lie in the range 3.89–4.12 eV. The bandgap decreased with the increase of Mn concentration in the films. The Mn concentrations in the films have been varied from 0% to 8.9% and was measured by energy dispersive X-ray analysis. The photoluminescence of the Mn doped ZnS nanoparticles was measured. The intensity of the PL peaks at first increased with the increase of Mn concentration in the films up to 3.8% of Mn doping and at a Mn concentration higher than this, the intensity of PL peak decreased. Nanocrystalline ZnS:Mn showed good field emission property with a turn on field lying in the range 5.26–6.78 V/μm for a variation of anode to sample distance from 60 μm to 100 μm.
    Optical Materials 08/2007; · 2.08 Impact Factor
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    ABSTRACT: The results on the measurement of conductivity of oxalic acid doped polyaniline in the temperature range , applying magnetic field up to 1 T in the frequency range 20–1 MHz are being reported. The dc conductivity has been interpreted by variable range hopping theory. The magnetoconductivity is positive, which is well explained by orbital magnetoconductivity theory. The frequency dependence of conductivity has been described by power law and the frequency exponent ‘s’ is found to be decreasing with temperature. The dielectric permittivity is large, which has been interpreted by the grain and grain boundary effect. Magnetic field dependence ac conductivity shows a positive variation. A firm theoretical explanation of magnetic field dependence of ac conductivity is still lacking. The different parameters like Mott characteristic temperature and localization length were calculated from the experimental data, the values of these parameters depend strongly on the resistivity ratio.
    Solid State Communications 01/2007; 143:358-363. · 1.53 Impact Factor
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    ABSTRACT: Zn1−xMnxO sub-micron fibrous thin films were synthesized by a simple sol–gel dip-coating technique. XRD pattern confirmed the hexagonal wurtzite structure of the synthesized material. Expansion of the c-axis lattice parameter has been observed with the increase of manganese content in the films. Manganese content (x) in the films varied from 0.0098–0.0568 and was determined by energy-dispersive X-ray analysis. The average diameter of the ZnO fibers were ∼700 nm whereas the length was several hundred micro-meters and hence the aspect ratio was quite large (>150). Branching and uneven growth occurred with the increase of manganese content as is evident from SEM analysis. Optical transmittance spectra showed absorption band due to characteristic d–d transition of Mn2+ ions nearly at 3 eV. The band gap, as determined from the transmittance spectra, decreased to 3.28 eV for x=0.0287 and then increased upto 3.38 eV for x=0.0568 as compared with the undoped film for which the band gap is 3.31 eV. Photoluminescence spectra of Zn1−xMnxO fibrous thin films on glass substrate for different doping levels were also studied which showed a broad UV band at ∼397 nm, a narrow blue–green band at ∼466 nm and another broad peak at ∼526 nm. Mn doping causes a large reduction in the intensity of the UV emission and small reduction in green emission intensity of the PL spectra.
    Physica B Condensed Matter 01/2007; · 1.28 Impact Factor
  • Indian Journal of Physics. 01/2007; 81(1):69-73.
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    ABSTRACT: Nanocrystalline ZnS thin films have been synthesized by radio frequency magnetron sputtering technique on glass and Si substrates at a substrate temperature 300 K. X-ray diffraction and selected area electron diffraction studies confirmed the formation of nanocrystalline cubic phase of ZnS in the films, although the target material was hexagonal ZnS. The particle size, calculated from the XRD patterns of the thin films was found in the range 2.06–4.86 nm. TEM micrographs of the thin films revealed the manifestation of ZnS nanoparticles with sizes in the range 3.00–5.83 nm. UV–vis–NIR spectrophotometric measurements showed that the films were highly transparent (∼90%) in the wavelength range 400–2600 nm with a blue shift of the absorption edge. The direct allowed bandgaps have been calculated and they lie in the range 3.89–4.44 eV. The particle size, calculated from the shift of direct bandgap, due to quantum confinement effect lying in the range 3.23–5.60 nm, well support the TEM results. The room temperature photoluminescence spectra of the films showed two peaks centered around 315 and 450 nm. We assigned the first peak due to bandgap transitions while the latter was due to sulfur vacancy in the films. The composition analysis by energy dispersive X-rays also supported the existence of sulfur deficiency in the films. The dielectric property study showed high dielectric constant (85–100) at a higher frequency (>5 kHz).
    Materials Research Bulletin. 01/2007;
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    ABSTRACT: Thin films of cadmium doped zinc oxide rod like microstructure have been synthesized by a very simple sol-gel dip coating technique. Sols were prepared from hydrated zinc oxide precursor and 2-methoxyethanol solvent with monoethanolamine as a sol stabilizer. XRD pattern confirmed the hexagonal wurtzite structure of the deposited ZnO films. Surface morphologies of the films have been studied by a scanning electron microscope and an atomic force microscope, which confirmed that the films are composed of densely packed randomly oriented nano/submicron rods with diameter in the range 300–400nm having various lengths. We proposed a possible growth mechanism for this rodlike structure. X-ray photoelectron spectroscopic study was used to determine the binding energies and the Zn 2p3/2, Cd 3d5 and O 1s peaks in the XPS spectra were located at 1021.08eV, 404.6eV and 529.8eV respectively, which confirmed the Cd doping in ZnO. Cadmium content in the film was estimated both from energy dispersive X-ray analysis and XPS measurement. Band gap energy determined from optical transmittance spectra systematically varied from 3.28eV to 3.15eV for 0% to 5.6% of Cd doping. Urbach parameter determined from the band tail of the transmittance spectra showed that it increased with doping percentage and this parameter for a fixed cadmium doping level decreased with increase of temperature.
    Journal of Sol-Gel Science and Technology 12/2006; 41(1):87-92. · 1.66 Impact Factor
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    ABSTRACT: We have observed low-macroscopic field electron emission from wide bandgap nanocrystalline Al doped SnO2 thin films deposited on glass substrates. The emission properties have been studied for different anode-sample spacings and for different Al concentrations in the films. The turn-on field and approximate work function were calculated and we have tried to explain the emission mechanism from this. The turn-on field was found to vary in the range 5.6–7.5V/μm for a variation of anode sample spacing from 80–120μm. The turn-on field was also found to vary from 4.6–5.68V/μm for a fixed anode-sample separation of 80μm with a variation of Al concentration in the films 8.16–2.31%. The Al concentrations in the films have been measured by energy dispersive X-ray analysis. Optical transmittance measurement of the films showed a high transparency with a direct bandgap ∼3.98eV. Due to the wide bandgap, the electron affinity of the film decreased. This, along with the nanocrystalline nature of the films, enhanced the field emission properties.
    Applied Physics A 12/2006; 86(1):139-143. · 1.69 Impact Factor
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    ABSTRACT: The field emission property of zinc sulphides nanorods synthesized in the thin film form on Si substrates has been studied. It is seen that ZnS nanorod thin films showed good field emission properties with a low-macroscopic turn-on field (2.9–6.3 V/μm). ZnS nanorods were synthesized by using radio frequency magnetron sputtering of a polycrystalline prefabricated ZnS target at a relatively higher pressure (10−1 mbar) and at a lower substrate temperature (233–273 K) without using any catalyst. Transmission electron microscopic image showed the formation of ZnS nanorods with high aspect ratio (>60). The field emission data were analysed using Fowler–Nordhiem theory and the nearly straight-line nature of the F–N plots confirmed cold field emission of electrons. It was also found that the turn-on field decreased with the decrease of nanorod's diameters. The optical properties of the ZnS nanorods were also studied. From the measurements of transmittance of the films deposited on glass substrates, the direct allowed bandgap values have been calculated and they were in the range 3.83–4.03 eV. The thickness of the films was ∼600 nm.
    Applied Surface Science 11/2006; · 2.54 Impact Factor
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    ABSTRACT: Electrical transport properties of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 ≤ T ≤ 300 K, applying magnetic fields up to 1 T in the frequency range 20 Hz–1 MHz. The room temperature dc resistivity increases with increase in Co content. The dc resistivity and magnetoresistivity of these samples have been interpreted in terms of the variable range hopping theory. The frequency dependence of conductivity has been described by a power law σ(ω) ∝ ωS. The value of s is found to be temperature dependent, which shows a decreasing trend with temperature. The correlated barrier hopping model is the most likely mechanism for the electron transport. The different physical parameters were calculated from the experimental data.
    Journal of Physics D Applied Physics 06/2006; 39(14):3047. · 2.53 Impact Factor
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    ABSTRACT: The low frequency (20 Hz to 1 MHz) ac conductivity and magnetoconductivity behaviour of ceramic nanocomposite (Ni-SiO2) at low temperature down to 77 K are reported. The frequency dependent conductivity followed the power law, σ(ω) ∝ ω s . The fractional exponent s is a function of temperature and was found to increase with increasing temperature. This type of variation may be attributed to small polaron hopping. A peak present in the loss tangent indicates the presence of a Debye relaxation process. The magnetoconductivity of the samples is positive, which strongly depends on frequency. A firm theoretical explanation of frequency dependent magnetoconductivity is still lacking.
    Czechoslovak Journal of Physics 01/2006; 56(2):201-210. · 0.42 Impact Factor

Publication Stats

167 Citations
53.83 Total Impact Points

Institutions

  • 2004–2013
    • Jadavpur University
      • Department of Physics
      Kolkata, Bengal, India
  • 2005–2009
    • National Institute of Technology, Durgapur
      Durgāpur, Mahārāshtra, India
  • 2004–2008
    • Bharati Vidyapeeth Deemed University
      Poona, Mahārāshtra, India
  • 1983
    • University of Calcutta
      Kolkata, Bengal, India