Advanced Centre of Research in High Energy Materials (ACRHEM)
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Browsing Advanced Centre of Research in High Energy Materials (ACRHEM) by Author "Ahmad, Muneer"
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ItemEffect of electron-phonon interaction and valence band edge shift for carrier-type reversal in layered ZnS/rGO nanocomposites( 2021-03-15) Natarajan, Vanasundaram ; Naveen Kumar, P. ; Ahmad, Muneer ; Sharma, Jitender Paul ; Chaudhary, Anil Kumar ; Sharma, Praveen KumarThe artificial stacking of nanohybrid films helps to enhance their properties and thus intrigues researchers to explore this possibility in emerging technologies. The layer-by-layer approach was used to fabricate samples of zinc sulfide/reduced graphene oxide (ZnS/rGO) by using spin coating technique. The structure and optoelectronic properties has been extensively studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–VIS-NIR spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Hall measurements. Raman spectrum elucidates the phonon contribution of ZnS and breathing mode of κ-point phonons and sp2 bonds of carbon atoms of rGO. The electron-phonon interactions reveal reduction in electron mobility and enhancement in holes contribution with rGO content leading to surface charge transfer doping (SCTD). XPS results explain the valence band edge and conduction band edge to form type-I band alignment to reconfirm carrier-type reversal. A change in the dispersion of refractive indices along with a small rise in the value of absorption coefficient in terahertz (THz) region for ZnS/rGO nanocomposite films has been observed. These results will open up new opportunities to furthering the science of this technologically important class of materials for future electronics.
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ItemSurface charge doping induced carrier type reversal in spin coated CdS/rGO layered nanohybrid films( 2020-01-01) Vanasundaram, Vanasundaram ; Ahmad, Muneer ; Chaudhary, A. K. ; Sharma, Praveen KumarThe growth of reduced graphene oxide (rGO) based semiconductor nanohybrids through simple, scalable, additive-free and cost-effective route has fascinated significant attention of researchers for both fundamental research areas and its commercial applications. In the present work, cadmium sulphide/reduced graphene oxide (CdS/rGO) films were sequentially or layer-by-layer (LBL) deposited by spin coating method. The samples were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-visible spectroscopy, Raman spectra and Hall measurements. The cubic phase of the CdS and formation of rGO was confirmed by XRD measurements. The FESEM micrographs elucidate a change in morphological features with rGO content in CdS/rGO nanohybrid films. The Raman spectra indicate the characteristic features for nanostructured CdS and rGO in these samples. Optical transmission is found to increase along with a decrease in optical gap with rGO content. Hall measurements showed the change in the majority carrier concentration with rGO content or the observation of surface charge transfer doping (SCTD) in these nanocomposites. The change in dispersion of refractive index with rGO content for CdS/rGO nanocomposites in terahertz (THz) spectral region has been observed. These results are very important for the development of new functionality of nanohybrid materials for emerging technologies.