Department Of Physics

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Author: search.filters.author.Mahapatra, S.K.Has files: Yes

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    Investigation of non linear dynamics of an excitable magnetron sputtering plasma
    (Elsevier, 2019) Sabavath, G; Shaw, P.K; Iyengar, A.N.S; Banerjee, I; Mahapatra, S.K.
    In this paper nonlinear dynamical behaviour of an excitable DC magnetron sputtering plasma has been investigated. Initially, plasma exhibited fixed point dynamics whereas with the increase in the discharge voltage, spikes were observed in the floating potential fluctuations. Furthermore, the increasing of discharge voltage resulted the increase in spikes. Power spectrum plot, normalized variance, recurrence plot and Hurst exponent are employed to extract the underlying feature of the floating potential fluctuations. A dip in the plot of normalized variance with variation in the control parameter has been seen, which is strongly indicative of coherence resonance like behaviour in the system. Power spectrum plot and Hurst exponent estimation are confirming the presence of coherence resonance behaviour. Apart from quantitative confirmation, visual verification of coherence resonance behavior has been carried out using recurrence plot analysis. It is noticed that the noise component increases with the increase in the discharge voltage and a suitable intrinsic noise strength plays an important role in generating the coherence resonance. © 2019
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    Paschen curve approach to investigate electron density and deposition rate of Cu in magnetron sputtering system
    (Taylor and Francis Inc., 2016) Gopikishan, S.; Banerjee, I.; Bogle, K.A.; Das, A.K.; Pathak, A.P.; Mahapatra, S.K.
    In this work, Paschen curve for argon gas was obtained during copper deposition using a DC magnetron sputtering system. Five process parameters of Paschen curve were used to obtain the electron density and deposition rate of the deposited nanostructured thin films. Plasma parameter such as electron density was correlated with the deposition rate. It is observed that a minimum deposition rate was obtained for the plasma process parameter corresponding to the Paschen minimum. This investigation helps to understand and optimize the quality of nanostructured thin films depending on the process parameters. ? 2016 Informa UK Limited, trading as Taylor & Francis Group.
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    Effect of plasma power on reduction of printable graphene oxide thin films on flexible substrates
    (Institute of Physics Publishing, 2018) Banerjee, I.; Mahapatra, S.K.; Pal, C.; Sharma, A.K.; Ray, A.K.
    Room temperature hydrogen plasma treatment on solution processed 300 nm graphene oxide (GO) films on flexible indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates has been performed by varying the plasma power between 20 W and 60 W at a constant exposure time of 30 min with a view to examining the effect of plasma power on reduction of GO. X-ray powder diffraction (XRD) and Raman spectroscopic studies show that high energy hydrogen species generated in the plasma assist fast exfoliation of the oxygenated functional groups present in the GO samples. Significant decrease in the optical band gap is observed from 4.1 eV for untreated samples to 0.5 eV for 60 W plasma treated samples. The conductivity of the films treated with 60 W plasma power is estimated to be six orders of magnitude greater than untreated GO films and this enhancement of conductivity on plasma reduction has been interpreted in terms of UV-visible absorption spectra and density functional based first principle computational calculations. Plasma reduction of GO/ITO/PET structures can be used for efficiently tuning the electrical and optical properties of reduced graphene oxide (rGO) for flexible electronics applications. ? 2018 IOP Publishing Ltd.