• M Pandey

      Articles written in Bulletin of Materials Science

    • Diamond like carbon coatings deposited by microwave plasma CVD: XPS and ellipsometric studies

      R M Dey M Pandey D Bhattacharyya D S Patil S K Kulkarni

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      Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage ranging from –100 V to –300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry techniques for estimating 𝑠𝑝3/𝑠𝑝2 ratio. The 𝑠𝑝3/𝑠𝑝2 ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are explained using sub-plantation picture of DLC growth. Our results clearly indicate that the film is composed of two different layers, having entirely different properties in terms of void percentage and 𝑠𝑝3/𝑠𝑝2 ratio. The upper layer is relatively thinner as compared to the bottom layer.

    • 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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