Research

Area of Research Interests

Light-matter interactions play a crucial role in understanding the underlying properties of the materials. My current research interests are focused on studying light-matter interaction in noval layered materials such as two-dimensional (2D) transition metal dichalcogenides (TMDCs) like MX2 (M= Mo, W and X= S, Se, Te). 2D nature of the atomically thin TMDCs leads to an increase in binding energy for electrons and holes because of reduced dielectric screening effect, large effective mass, and strong quantum confinement, allowing the formation of a large variety of excitonic quasi-particles like excitons, trions and bi-excitons. These excitonic quasi-particles and their coupling with phonons and charge carriers play a crucial role in controlling the optical properties of atomically thin semiconducting 2D materials. 

I try to understand the phonons dynamics, quasiparticle excitations and their coupling with phonons, photons and charge carriers, thermal properties and role of interlayer interaction as a function of temperature, thickness, incident excitation energy and rotation of incident and scattered light polarization direction in this kind of 2D materials using the Raman and photoluminescence (PL) spectroscopic techniques.

LoW-Dimensional Materials 

Transition Metal dichalcogenides (TMDCs): An Introduction 

Two dimensional layered transition metal dichalcogenides (TMDCs) have emerged as promising materials for future potential applications due to their unique properties. TMDCs are the materials in family of 2D materials with a common atomic formula MX2, where M is the transition-metal atom (Mo or W), and X is the chalcogen (S, Se or Te). In MX2, each single layer is consist of three sub-atomic-layer in which a sheet of transition-metal atom (M) is sandwiched between two sheet of chalcogen atoms (X) forming the X-M-X type of atomic structure, and these sub-atomic layers are held together by strong covalent bond between M and X atoms. However, in bulk/layered structure, adjacent layers are bounded together by weak van der Waals type force, and this weak force is very interesting feature of these 2D materials, because it offer an opportunity to achieve single layer thick system from bulk crystal by even a very easy method called mechanical exfoliation method.The properties of these 2D materials are strongly dependent on the number of layers  For example, these show the indirect to direct band gap transition when the thickness is reduced to monolayer from bulk. TMDCs with monolayer thickness have attracted a considerable attention due to their specific optical, electronic and optoelectronic properties, which make them a promising materials for high performance future electronic and optical devices.