Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Applied Physics (PhD)

Administrative Home Department

Department of Physics

Advisor 1

Jae Yong Suh

Committee Member 1

Yoke Khin Yap

Committee Member 2

Ranjit Pati

Committee Member 3

Yun Hang Hu


Two-dimensional layered materials such as graphene and transition metal dichalcogenides have gained a lot of attention because of their distinctive chemical, optical, and electronic properties. Transition metal dichalcogenides can have a tunable bandgap in the range of 1 − 3 eV (visible), which enables their applications in ultrathin field effect transistors, photovoltaics, sensors, and optoelectronic devices. They exhibit an indirect-to-direct band gap transition when thinned down from bulk to a single layer. They show strong photoluminescence, electron–photon interaction, valley pseudospin, nonlinear optical response, and lack of dangling bonds. Many exotic phenomena appear when materials are thinned to nanoscale size because of the quantum confinement effect and the symmetry changes in lower dimensions. The stacking of two-dimensional transitional metal dichalcogenides with a controlled twist angle creates “van der Waals” heterostructures, which has opened a pandora box that allows us to explore new quantum properties. These “van der Waals” structures can host Mott insulating states, topological states, and correlated electron physics.

In this dissertation, to explore these intriguing properties, I focused on fabricating bilayers of tungsten disulfide (WS2) with a controlled twist angle. The new transfer method can minimize trapped interfacial impurities, chemical residue cracks, or mechanical damage during the transfer process. Furthermore, I studied the electronic and optical properties of stacked bilayers and the role of twist angle in tuning these properties.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Available for download on Friday, July 26, 2024