• D Bhattacharya

      Articles written in Bulletin of Materials Science

    • ZrO2 as a high-𝜅 dielectric for strained SiGe MOS devices

      R Mahapatra G S Kar C B Samantaray A Dhar D Bhattacharya S K Ray

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      The potential of ZrO2 thin film as a high-𝜅 gate dielectric for scaled MOSFET devices has been studied. ZrO2 has been deposited directly on a Si0.8Ge0.2 substrate by reactive RF magnetron sputtering. An equivalent oxide thickness of < 20 Å with a leakage current of the order of 10–4 A/cm2 at 1 V has been obtained. Well-behaved capacitance–voltage characteristics with an interface state density of 2 × 1011 cm–2eV–1 have been achieved. The deposited dielectric exhibits low charge trapping under constant current stressing.

    • Optical and mechanical properties of diamond like carbon films deposited by microwave ECR plasma CVD

      S B Singh M Pandey N Chand A Biswas D Bhattacharya S Dash A K Tyagi R M Dey S K Kulkarni D S Patil

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      Diamond like carbon (DLC) films were deposited on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapour deposition (CVD) process using plasma of argon and methane gases. During deposition, a d.c. self-bias was applied to the substrates by application of 13.56 MHz rf power. DLC films deposited at three different bias voltages (–60 V, –100 V and –150 V) were characterized by FTIR, Raman spectroscopy and spectroscopic ellipsometry to study the variation in the bonding and optical properties of the deposited coatings with process parameters. The mechanical properties such as hardness and elastic modulus were measured by load depth sensing indentation technique. The DLC film deposited at –100 V bias exhibit high hardness (∼ 19 GPa), high elastic modulus (∼ 160 GPa) and high refractive index (∼ 2.16–2.26) as compared to films deposited at –60 V and –150 V substrate bias. This study clearly shows the significance of substrate bias in controlling the optical and mechanical properties of DLC films.

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