• K Shalini

      Articles written in Bulletin of Materials Science

    • Thermodynamic investigation of the MOCVD of copper films from bis(2,2,6,6-tetramethyl-3,5-heptadionato)copper(II)

      Sukanya Mukhopadhyay K Shalini Anjana Devi S A Shivashankar

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      Equilibrium concentrations of various condensed and gaseous phases have been thermodynamically calculated, using the free energy minimization criterion, for the metalorganic chemical vapour deposition (MOCVD) of copper films using bis(2,2,6,6-tetramethyl-3,5-heptadionato)copper(II) as the precursor material. From among the many chemical species that may possibly result from the CVD process, only those expected on the basis of mass spectrometric analysis and chemical reasoning to be present at equilibrium, under different CVD conditions, are used in the thermodynamic calculations. The study predicts the deposition of pure, carbon-free copper in the inert atmosphere of argon as well as in the reactive hydrogen atmosphere, over a wide range of substrate temperatures and total reactor pressures. Thin films of copper, grown on SiO2/Si(100) substrates from this metalorganic precursor by low pressure CVD have been characterized by XRD and AES. The experimentally determined composition of CVD-grown copper films is in reasonable agreement with that predicted by thermodynamic analysis.

    • Oriented growth of thin films of samarium oxide by MOCVD

      K Shalini S A Shivashankar

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      Thin films of Sm2O3 have been grown on Si(100) and fused quartz by low-pressure chemical vapour deposition using an adducted 𝛽-diketonate precursor. The films on quartz are cubic, with no preferred orientation at lower growth temperatures (∼ 550°C), while they grow with a strong (111) orientation as the temperature is raised (to 625°C). On Si(100), highly oriented films of cubic Sm2O3 at 625°C, and a mixture of monoclinic and cubic polymorphs of Sm2O3 at higher temperatures, are formed. Films grown on either substrate are very smooth and fine-grained. Infrared spectroscopic study reveals that films grown above 600°C are free of carbon.

    • Thermodynamic analysis of growth of iron oxide films by MOCVD using tris(𝑡-butyl-3-oxo-butanoato)iron(III) as precursor

      Sukanya Dhar K Shalini S A Shivashankar

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      Thermodynamic calculations, using the criterion of minimization of total Gibbs free energy of the system, have been carried out for the metalorganic chemical vapour deposition (MOCVD) process involving the 𝛽-ketoesterate complex of iron [tris(𝑡-butyl-3-oxo-butanoato)iron(III) or Fe(tbob)3] and molecular oxygen. The calculations predict, under different CVD conditions such as temperature and pressure, the deposition of carbon-free pure Fe3O4, mixtures of different proportions of Fe3O4 and Fe2O3, and pure Fe2O3. The regimes of these thermodynamic CVD parameters required for the deposition of these pure and mixed phases have been depicted in a `CVD phase stability diagram’. In attempts at verification of the thermodynamic calculations, it has been found by XRD and SEM analysis that, under different conditions, MOCVD results in the deposition of films comprising pure and mixed phases of iron oxide, with no carbonaceous impurities. This is consistent with the calculations.

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