• S Dhar

      Articles written in Bulletin of Materials Science

    • An investigation of the growth of In0·53Ga0·47As layers on InP by liquid phase epitaxy

      S Dhar Mala Mitra J B Roy B R Nag

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      Liquid phase epitaxial growth of lattice-matched In0·53Ga0·47As layers on InP substrates is investigated with particular emphasis on the role of interface defects on layer quality. By differential Hall measurements it is established that a bad interface, resulting from the thermal decomposition of InP substrate prior to growth, degrade the electron mobility in all parts of the layer and the effect is most pronounced at regions close to the interface. However layers with much better physical and electrical characteristics are grown following steps to ensure substrate surfaces free from any thermal damage.

    • ERD facility for analysis of hydrogen and deuterium in solids

      T Som S Dhar N Banerji K Ramakrishnan V N Kulkarni

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      Hydrogen is the lightest element in nature, and so, its detection and quantitative analysis is difficult by the conventional methods utilized for other elements. In the recent years the technique of elastic recoil detection analysis (ERD) using 1–2 MeV He+ beam has been developed to quantitatively and simultaneously analyze hydrogen and its isotopes in solids. Such a facility has been set up using the 2 MeV Van-de-Graaff accelerator at IIT Kanpur. It facilitates H and D analysis in a material up to a depth of ∼ 1µm with a detection sensitivity of 0·1 at.% and depth resolution of about 300 Å. The application potential of this setup is illustrated by presenting the results of measurements performed on Al:H:D systems prepared by plasma source ion implantation and highTc YBCO pellets exposed to humid atmosphere.

    • Characterization of deep level defects in Si irradiated with MeV Ar+ ions using constant capacitance time analyzed transient spectroscopy

      P K Giri S Dhar V N Kulkarni Y N Mohapatra

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      An isothermal spectroscopic technique called time analyzed transient spectroscopy (TATS) in the constant capacitance (CC) mode has been used to characterize electrically active defects in the MeV Ar+ implanted silicon. The problems associated with high defect density and the presence of damaged region in the as-implanted material are overcome by CC-TATS method. The CC-TATS spectra of the as-implanted sample shows two positive peaks and an attendant negative peak. Two distinct traps have also been identified using thermally stimulated capacitance method modified to operate in constant capacitance mode. Variable pulse width measurements using CC-TATS show exponential capture kinetics in contrast to extremely slow capture observed in conventional deep level transient spectroscopy (DLTS) experiment. The results indicate that trapping behaviour is due to point-like defects associated with extended defects such as dislocation and stacking fault.

    • Ar ion induced copper germanide phase formation at room temperature

      S Dhar T Som Y N Mohapatra V N Kulkarni

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      The copper germanide phase Cu3Ge which is emerging as an alternative material for making contacts and interconnects for semiconductor industry has been produced across the interface of Cu/Ge bilayers by ion beam mixing at room temperature using 1 MeV Ar ions. The dose dependence of the thickness of the mixed region shows a diffusion controlled mixing process. The experimental mixing rate and efficiency for this phase are 5·35 nm4 and 10·85 nm5/keV respectively. At doses above 8 × 1015 Ar/cm2 the formation and growth of another copper rich phase Cu5Ge has been observed. The present theoretical models are inadequate to explain the observed experimental mixing rate.

  • Bulletin of Materials Science | News

    • 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

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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