Doctoral Dissertations
Date of Award
12-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Physics
Major Professor
Gong Gu
Committee Members
Norman Mannella, Haidong Zhou, Joon Sue Lee
Abstract
Atomically thin two-dimensional (2D) materials and heterostructures have emerged as a frontier in materials science, offering unique physical properties and unprecedented potential for technological applications. These materials, such as graphene, transition metal dichalcogenides (TMDs), and hexagonal boron nitride (hBN), exhibit exceptional electronic, optical, and mechanical characteristics due to their reduced dimensionality and strong quantum confinement effects. As research progresses, the disassembling and reassembling the 2D materials to realize these heterostructures is still a hot and ongoing research. Ensuring clean interfaces and high-quality materials is crucial to access these novel properties.
After a brief introduction and literature review, Chapter 3 introduces different novel approaches to the stacking of different 2D materials and the fabrication of heterostructures with tailored properties, enabling the exploration of novel phenomena such as phase change investigation of PdSe2 and the memcapacitive and memresistive effects of stacked nanosheets of PdSe2. These heterostructures are pivotal for advancing nanoelectronics, photonics, and phase transition devices. A simple polymer-free graphene transfer technique is introduced that improves the quality of transferred graphene.
Chapter 4 of the dissertation investigates the behaviour of various excitons such as free exciton, bound exciton along with defect states in a partially encapsulated GaSe by varying the GaSe thickness and temperature (4 to 295 K). This further expands our understanding of excitons and deep defects in 2D GaSe. This knowledge is crucial for the future use of GaSe in nano-optoelectronics, particularly when it comes to manipulating its optical properties.
Finally, chapter 5 investigates the structural evolution and correlated optical properties of the various alloys between PdSe2 and PdTe2 with different Te fractions. we have observed several phase transitions using Raman spectroscopy, and transitions from PdSe2 ambipolar transport characteristics to n-type in PdSe1.8Te0.2, and subsequently to p-type in PdSe1.5Te0.5 as Te doping increases.
Recommended Citation
Olunloyo, Olugbenga Adeyemi, "Atomically thin 2D Materials and Heterostructures: Preparation, Characterization, and Applications. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/11321
