1. University of Calcutta, Department of Electronic Science, 92 A.P.C. Road, Kolkata 700009, IndiabVidyasagar University, Department of Electronics, Midnapore 721102, India
2. University of Calcutta, Department of Electronic Science, 92 A.P.C. Road, Kolkata 700009, IndiacUniversity of Calcutta, Centre for Research in Nanoscience and Nanotechnology, Salt Lake, Kolkata 700098, India