Surface charge doping induced carrier type reversal in spin coated CdS/rGO layered nanohybrid films

Abstract

The 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.