• BIBHU P SWAIN

      Articles written in Bulletin of Materials Science

    • Effect of nitrogen flow rate on the mechanical properties of CVD-deposited SiCN thin films

      DHRUVA KUMAR RANJAN Kr GHADAI SOHAM DAS ASHIS SHARMA BIBHU P SWAIN

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      Silicon carbonitride (SiCN) thin films were deposited on p-Si (100) substrates with different N₂ flow rates using SiC and Si₃N₄ powder precursors by chemical vapour deposition. To investigate the structural, vibrational and mechanical properties, the SiCN thin films were characterized by atomic force microscopy, Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared and nanoindentation techniques. The XRD results reveal nanocrystals embedded with amorphous networks in the SiCN thin films. An increase in the $I$_{D}/$I$_{G} ratio with an increase in the N₂ flow rate indicated the increase of sp³ bonds in the SiCN thin film. The hardness ($H$), Young’s modulus ($E$), plasticity index ($H/E$) and ($H$³/$E$²) increase with an increase in the N₂ flow rate.

    • Bandgap engineering of PEDOT:PSS/rGO a hole transport layer for SiNWs hybrid solar cells

      RABINA BHUJEL SADHNA RAI UTPAL DEKA GAUTAM SARKAR JOYDEEP BISWAS BIBHU P SWAIN

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      Silicon nanowire (SiNW) hybrid solar cell has been fabricated using PEDOT:PSS and rGO-PEDOT:PSS as the organic hole transport layer. The electrical characterization of the as-fabricated solar cell was done by both dark and photo $J–V$ characteristic curves. Vertically aligned arrays of SiNWs have been synthesized by following the electroless metal-assisted chemical etching method, as confirmed by both the scanning electron microscopy and atomic force microscopy images. The structural properties of SiNWs, PEDOT:PSS and rGO-PEDOT:PSS were characterized with thehelp of X-ray diffraction and Raman characterization techniques. The bandgap of PEDOT:PSS comes out to be 1.77 eV asobtained from the UV–visible and photoluminescence spectra. In addition, the bandgap of PEDOT:PSS was 1.76 eV and for reduced graphene oxide (rGO) it was 0.04 eV, as obtained from the cyclic voltammetry curve. rGO-PEDOT:PSS heterojunction showed excellent $J–V$ characteristic property in the dark and under the illumination of 1 sun. Hence the incorporation of rGO in PEDOT:PSS can improve the photovoltaic properties by increasing the conductivity of the hole transport layer, making a good interface between organic–inorganic heterojunction as well as by reducing the recombination of electron–hole pairs.

    • Silver-decorated reduced graphene oxide nanocomposite for supercapacitor electrode application

      NAOREM ARUNA DEVI SAYANTAN SINHA W ISHWARCHAND SINGH SUMITRA NONGTHOMBAM BIBHU P SWAIN

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      Silver-decorated reduced graphene oxide (Ag@rGO) nanocomposite was synthesized via a facile chemical reduction method, and its morphology, functional groups, structure, optical and electrical characteristics were investigated.Large distributions of spherical Ag nanoparticles with particle size ranging from 108 to 126 nm anchored into rGO sheets were observed. The energy dispersive X-ray confirms the presence of carbon, oxygen and silver elements in the Ag@rGO nanocomposite. Fourier-transform infrared spectrum exhibited stretching vibrations due to C=O, C–H$_2$, C–O,C=C, O–H and Ag–O bonds in Ag@rGO nanocomposite. X-ray diffraction results of Ag@rGO nanocomposite confirmthe formation of rGO and metallic Ag nanoparticles exhibiting FCC structure. The bandgap and ID/IG values of Ag@rGO nanocomposite were obtained as 2.76 and 1.49 eV respectively. Moreover, the study of electrochemical properties ofAg@rGO nanocomposite was carried out, where the maximum specific capacitance of 717.3 and 433.05 F g$^{-1}$ was achieved at 5 mV s$^{-1}$ scan rate and 1 A g$^{-1}$ current density. Moreover, the impedance spectroscopy study exhibited thecharge transfer resistance (R$_{CT}$) value as 6.98 and 71.29${\Omega}$ from the Nyquist and Bode plots. I–V characteristics curveshows that the addition of Ag into rGO increases its electrical conductivity. Thus, the results of Ag@rGO nanocompositecan be suitable for supercapacitor application.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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