• Dinesh Kumar

      Articles written in Bulletin of Materials Science

    • Semiconductor applications of plasma immersion ion implantation technology

      Mukesh Kumar Rajkumar Dinesh Kumar P J George

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      Many semiconductor integrated circuit manufacturing processes require high dose of implantation at very low energies. Conventional beam line ion implantation system suffers from low beam current at low energies, therefore, cannot be used economically for high dose applications. Plasma immersion ion implantation (PIII) is emerging as a potential technique for such implantations. This method offers high dose rate irrespective of implantation energy. In the present study nitrogen ions were implanted using PIII in order to modify the properties of silicon and some refractory metal films. Oxidation behaviour of silicon was observed for different implantation doses. Diffusion barrier properties of refractory barrier metals were studied for copper metallization.

    • Effect of thin Mo2C layer on thermal stability of Si/SiO2/Ti/Cu system

      C C Tripathi Mukesh Kumar Dinesh Kumar

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      The effect of introducing a thin Mo2C (30 nm) layer between Ti and Cu on the thermal stability of Si/SiO2/Ti/Cu system was studied using four-point probe (FPP), scanning electron microscopy (SEM), energydispersive X-ray spectroscopy (EDAX) and X-ray diffraction (XRD) techniques. The measured value of the sheet resistance in the bi-layered diffusion barrier structure does not show any change up to an annealing temperature of 750°C. The sheet resistance when measured after annealing at 800°C marginally increases but less than twice its value at room temperature. The XRD analysis indicated no copper diffusion and the formation of Cu3Si phase up to 800°C. The bi-layered barrier structure annealed at elevated temperature shows copper-depleted and agglomerated regions. The sheet resistance measurement, study of surface morphology and the XRD analysis confirm that the insertion of thin Mo2C layer increases the thermal stability of the system from 400°C to 750°C. The increased thermal stability of the system is ascribed to longer diffusion path length in the bi-layered system probably because of grain boundaries mismatch at Ti–Mo2C interface.

    • Synthesis and characterization of nickel/barium hexa-aluminate composite coatings

      Dinesh Kumar Sampada Gurav Vikram Jayaram Sanjay Kumar Biswas

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      Electrodeposition of nickel/barium hexa-aluminate (Ni/BHA) composite coatings has been carried out from a Watt’s bath on mild steel substrate. BHA powders with plate habit were synthesized by solution combustion synthesis followed by heat treatment to ensure complete conversion to the hexa-aluminate phase. Heat treated material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with X-ray analysis. The dispersion behaviour and stability of BHA suspensions with cationic and anionic surfactants at room temperature were studied by dynamic light scattering under different pH. The influence of BHA concentration in the electrolytic bath, deposition temperature, pH, current density and duty cycle on particle incorporation in the coatings were studied and conditions for maximum particle incorporation were established. Coatings with a roughness of about 0.4 𝜇m were produced by using this technique. Effect of BHA content on microhardness was also investigated. A reasonably good thickness of the coatings was achieved in a given set of conditions.

    • Effect of anodization on corrosion behaviour and biocompatibility of Cp-titanium in simulated body fluid

      Archana Singh B P Singh Mohan R Wani Dinesh Kumar J K Singh Vakil Singh

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      The objective of this investigation is to study the effectiveness of anodized surface of commercial purity titanium (Cp-Ti) on its corrosion behaviour in simulated body fluid (SBF) and proliferation of osteoblast cells on it, to assess its potentiality as a process of surface modification in enhancing corrosion resistance and osseointegration of dental implants. Highly ordered nano-porous oxide layer, with nano-sized pores, is developed on the surface of Cp-Ti through electrochemical anodization in the electrolyte of aqueous solution of 0.5% HF at 15 V for 30 min at 24 °C. The nano-porous feature of the anodized surface is characterized by field-emission scanning electron microscope (FESEM). Pores of some anodized samples are sealed by exposing the anodized surface in boiling water. Corrosion behaviour of the anodized specimen is studied in Ringer’s solution at 30 ± 2 °C, using electrochemical impedance and cyclic polarization technique. Biocompatibility of the anodized surface is accessed using MG63 osteoblast cells. Both corrosion as well as pitting resistance of Cp-Ti in simulated body fluid are found to be highest in the anodized and sealed condition and followed in decreasing order by those of anodized and unanodized ones. Significantly higher MG63 osteoblast cell proliferations are found on the anodized surface than that on the unanodized one. Anodized Cp-Ti develops nano-size surface pores, like that of natural bone. It enhances corrosion and pitting resistance and also the process of osteoblast cell proliferation on Cp-Ti.

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