Synthesis and characterization of 2D 3R-phase Mo₀.₄₅W₀.₅₅S₂

• Main Author: Wang, Mowei
• Other Authors: Liu Zheng
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials::Microelectronics and semiconductor materials
• Online Access: https://hdl.handle.net/10356/166604
• Institution: Nanyang Technological University

Transition metal dichalcogenides (TMDs) such as MoS2 and WS2 are a trending research topic in the field of 2D materials for microelectronic devices. However, there has not been much research work on the 3R phase, a polytype of TMD which exhibits unique electronic and optical properties. In this project, 3R phase Mo0.45W0.55S2, a newly synthesised material by chemical vapour transport (CVT) was studied. The characterization of its composition and structure was done by energy dispersive X-ray spectroscopy and scanning transmission electron microscopy. Mechanical exfoliation methods were extensively studied and optimised to isolate high yield 2D 3R Mo0.45W0.55S2 layers for applications. Layer dependent properties of 3R Mo0.45W0.55S2 were characterized by atomic force microscope, Raman spectroscopy and photoluminescence spectroscopy. It is believed that the data obtained in this project will provide a valuable reference for future studies of Mo0.45W0.55S2. The described scotch tape exfoliation method with optimised parameters could also be used for efficient isolation of 2D layers of any TMD materials.