Structure, microstructure and physical properties of ZnO based nanocomposites

thesis entitled “Structure, microstructure and physical properties of ZnO based nanocomposites” deals mainly with the structural, photoluminescence and photoconductivity properties of different ZnO-based nanocomposite materials in various forms. These properties have been discussed by analyzing the role of defect states and band alignment of the composite materials in controlling the optical and opto electrical properties of the materials. Among all the wide band gap semiconductors, nanostructured ZnO (Eg ̴ 3.37 eV) has been paid a great attention by the scientific world due to its high exciton binding energy (60 meV) which is much higher as compared to GaN and ZnSe having the same semiconductor properties of ZnO and also because its ability to grow in different forms of nanostructures by cheaper synthesis methods. In this work, the nanocomposite structures have been grown by using different chemical synthesis processes and the properties of the composite nanostructures have been compared to the as-grown ZnO nanostructures synthesized by aqueous chemical growth (ACG) and sol-gel techniques. The characterizations of the as-grown and nanocomposite samples have been done using the techniques such as xray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), photoconductivity measurements etc. The entire thesis consists of ten (10) chapters. It starts with a general introduction and ends with a summary of the results. A brief review on the past and recent works on ZnO based nanocomposites reported in the literature has been presented before the respective chapters. Experimental techniques used for characterizations of the samples have also been described in detail.The research was carried out under the supervision of Prof. Durga Basak of the Solid State Physics division under SPS [School of Physical Sciences]The research was being conducted under CSIR fellowship and research gran