Synthesis and Electronic Properties of Emerging Two-Dimensional Materials: MoO2, In4Se3, and Ti3C2Tx MXene

The isolation and demonstration of the extraordinary properties of graphene sparked interest in other two-dimensional (2D) materials with very diverse structures and physical characteristics. The still-growing family of 2D materials now includes a variety of single-element crystals, such as silicene, borophene, and phosphorene, hexagonal boron nitride (hBN), transition metal chalcogenides (TMDs), layered carbides and oxides. The research in this Ph.D. dissertation focuses on investigating the fundamental electronic properties of unconventional low-dimensional materials. In this work, (1) I found a scalable synthesis of metallic MoO2 nanoplatelets and characterized their electronic properties. It was revealed that MoO2 has a higher conductivity than MoS2, a widely studied 2D material. (2) A method was conceived to exfoliate thin flakes, with various morphologies, of the highly anisotropic material, In4Se3. The exfoliated flakes exhibit charge carrier mobilities of 46 〖cm〗^2/(V s) at room temperatures and 58 〖cm〗^2/(V s) at 77 K. It was demonstrated that In4Se3 exhibits a fast and anisotropic photoresponse in the visible range of spectrum. (3) Finally, the electronic properties of monolayer Ti3C2Tx MXene were investigated. The MXene devices exhibited a reproducible negative photoresponse when illuminated by white light and lasers of different wavelengths