• K S R K Rao

      Articles written in Bulletin of Materials Science

    • Influence of deviation from stoichiometry on the photoluminescence in CdTe doped with indium

      Suma Gurumurthy K S R K Rao A K Sreedhar H L Bhat B Sundersheshu R K Bagai Vikram Kumar

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      Low temperature photoluminescence of vacuum and cadmium annealed CdTe:In is reported here. A new peak at ∼ 1·14 eV related to transitions from the conduction band to an acceptor involving a tellurium vacancy has been observed.

    • Pulsed laser deposition of indium antimonide

      R Venkataraghavan K M Satyalakshmi K S R K Rao A K Sreedhar M S Hegde H L Bhat

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      Single crystalline oriented films of indium antimonide have been grown on cadmium telluride substrates by the pulsed laser deposition technique. The films were (111) oriented which is the substrate orientation. The composition of the grown films were found to deviate from that of the target owing to loss of antimony during evaporation. This deviation from stoichiometry led to film-substrate reaction, resulting in mixed interface. The antimony deficiency in the films were controlled by correcting the stoichiometry, which led to avoiding mixed interfaces. The stoichiometric films showed good surface morphology and well defined sharp interfaces. The IR transmission spectrum showed sharp band to band absorption and effective detection in the MWIR.

    • Design and fabrication of liquid phase epitaxy system

      R Venkataraghavan N K Udayashankar Blasius Victor Rodrigues K S R K Rao H L Bhat

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      The design and fabrication of a simple and versatile liquid phase epitaxial (LPE) system has been described. The present LPE system makes use of the horizontal multi-bin boat and slider arrangement which enables the growth of even multilayered structures. The growth chamber is heated by a single-zone resistive furnace precisely controlled through a Eurotherm 902P temperature programmer and controller. The vacuum manifolds and accessories are set up in such a way as to ensure high vacuum needed for growth experiments. The provision is also made to admit high purity gases like hydrogen or nitrogen into the growth chamber. The design has been kept simple without sacrificing the versatility and adaptability for novel growth experiments. The typical films grown by this LPE system are also presented.

    • Thickness dependent electrical properties of CdO thin films prepared by spray pyrolysis method

      L C S Murthy K S R K Rao

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      A large number of thin films of cadmium oxide have been prepared on glass substrates by spray pyrolysis method. The prepared films have uniform thickness varying from 200–600 nm and good adherence to the glass substrate. A systematic study has been made on the influence of thickness on resistivity, sheet resistance, carrier concentration and mobility of the films. The resistivity, sheet resistance, carrier concentration and mobility values varied from 1·56–5·72×10−3 Ω-cm, 128–189 Ω/□, 1·6–3·9×1021 cm−3 and 0·3–3 cm2/Vs, respectively for varying film thicknesses. A systematic increase in mobility with grain size clearly indicates the reduction of overall scattering of charge carriers at the grain boundaries. The large concentration of charge carriers and low mobility values have been attributed to the presence of Cd as an impurity in CdO microcrystallites. Using the optical transmission data, the band gap was estimated and found to vary from 2·20–2·42 eV. These films have transmittance around 77% and average reflectance is below 2·6% in the spectral range 350–850 nm. The films aren-type and polycrystalline in nature. SEM micrographs of the CdO films were taken and the films exhibit clear grains and grain boundary formation at a substrate temperature as low as 523 K.

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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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