HYDROTHERMAL SYNTHESIS OF TMD NANOSTRUCTURES ALONG WITH ELUCIDATION OF DOUBLE ZONE THERMAL CVD AND PECVD

Abstract

The scientific world has always been in hunt of opportunities that have the potential to impact not only academia but the industrial world too. It is the result of the quest to explore new technological advances that a new scientific tool in the form of nanotechnology has emerged. It is the science to unravel the properties of the atomic world and to use those properties for revolutionary changes. An example of revolutionary change is the small size of transistors that have influenced the size of computers and thus our lives greatly. The fascinating microscopic world has lots of hidden features in it. Demystifying those features and exploring the unprecedented properties of that world has created new avenues in diverse fields. Before learning the properties of different materials, synthesizing them is a major task. As the future is more about making things smaller and tinier for various applications, the hunt for better methods is always a hot topic of research. Different approaches are used for the synthesis depending upon the factors like the type of precursors, structure, composition and morphology of the product required, and others. Each technique offers a wide range of advantages and disadvantages, thus, learning about them and their usage in some specific conditions is mandatory in this field. In the present work, numerous synthesis techniques viz. Hydrothermal/Solvothermal, Sonochemical, Chemical Vapour Deposition, Sol-Gel, and Chemical Exfoliation are discussed. Their mechanism is briefly discussed along with advantages and disadvantages.

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Furthermore, to explore the properties of nanostructures, different attempts of synthesis have been made and reported briefly here. Initially, attempts have been made to synthesize WS2 nanostructures via Hydrothermal Synthesis at varied conditions. Their observations and results have been discussed and implications have been drawn from the results. After that, to study more about the TMDs and the heterojunctions, attempts have been made to synthesize the nanostructures of ZnO/MoS2 composite via the Hydrothermal Synthesis. Two approaches have been used here. In one approach, prepared ZnO nanostructures have been put into the procedure of preparation of MoS2 nanostructures while in the other approach, prepared MoS2 nanostructures have been put into the procedure of preparation of ZnO. The results of both the approaches and conclusions drawn from them are discussed in further chapters. Eventually, two variants of another technique CVD that are Double Zone Thermal CVD and PECVD present in NRL, DTU, Delhi have been explored and studied. Both the deposition variants i.e., Double Zone Thermal CVD and PECVD offer a wide range of advantages like the uniformity of thin films along with easy accessibility over a wide range of precursors for nanomaterial synthesis. Thus, the principle, working and technical details as well as the advantages and disadvantages associated with the above-mentioned systems are also discussed in the present work.