Research Projects

Two-dimensional (2D) transition metal dichalcogenides (TMDCs), atomic thickness, having tunable band gaps and strong light-matter interactions, offer superior flexibility and scalability compared to traditional 3D semiconductors. These make them ideal for applications in next-generation quantum technologies. Among the TMDCs, Vanadium disulfide (VS₂) stands out as a prime candidate exhibiting superior optical properties. Also, it has various polymorphs depending on the stacking orientation of the two successive layers such as 1T (Trigonal), 2H (Hexagonal), and 3R (Rhombohedral). 3R polymorph is of particular interest due to its existence of a non-centrosymmetric nature, which leads to non-zero dipole moment irrespective of the number of layers. Thus, 3R polymorph of VS₂ will outperform with the 2H and 1T polymorphs. Another peculiar feature of 3R is theoretically reported optical nonlinear susceptibility 2500 pm/V, which is adequately higher than any other 2D TMDCs, owing to its narrower bandgap having in the range of 0.6 eV to 1 eV. However it holds substantial promise, its broad implementation is hindered by challenges in achieving phase selective (3R) and its scalability in synthesis, and comprehensive understanding of its growth mechanisms. Thus, synthesizing VS₂ in a large area with polymorph control is demanding in the 2D world. Moreover, exploring nonlinear optical phenomenon such as ferroelectricity and nonlinear optical susceptibility, are highly considerable for the development of future nonlinear optical devices and quantum technology. Presently, various conventional chemical vapor deposition (CVD) methods utilize alkali halides to develop monolayer VS₂ films with continuous carrier flow dynamics during the growth process. These processes are hindering the structural, optical, and electrical quality of the VS₂ films. To overcome these challenges, our proposed approach i.e., by changing the continuous carrier gas flow dynamics to pulse flow carrier dynamics during the CVD process will help to synthesize high-quality phase selective (3R) and its scalable VS₂ films with varying layer numbers. Further, my expertise in synthesized 3R-MoS₂ and its detailed characterizations using pulse flow carrier gas from my PhD work in CVD, will help to develop a potential method to synthesize 3R-VS₂ films. Moreover, the computational fluid dynamic (CFD) simulations will be performed to comprehend the heat and mass transport during the growth process to synthesize VS₂. To characterize the deposited 3R-VS₂ films, we will utilize various structural, microscopic, and spectroscopic techniques. This research proposal aims to address these gaps by utilizing pulsed flow carrier gas dynamics and optimizing thermodynamic variables in the CVD method. We aim to develop a reproducible high-quality phase selective (3R) and its scalable synthesis process for VS₂. To validate its detailed nonlinear optical properties for the development of quantum technologies.