THE STRUCTURE AND CHEMISTRY OF EPITAXIAL 2D CHALCOGENIDES
Molybdenum based transition metal dichalcogenides have drawn widespread attention from the scientific community as they hold high promise in the field of semiconductors and valleytronics. Weak van der Waals (vdW) forces between layers eliminate substrate lattice constraints and allow epitaxial growth on different materials. Alloying the metallic or chalcogen species will potentially allow us access to intermediate structural, optical and electronic parameter space. In this work, we report the molecular beam epitaxial growth of alloyed MoSe2-xTex thin films on 3D substrates: CaF2 and GaAs substrates. Growth at 400C by co-injection of the chalcogen species results in preferential Se incorporation. By pulsing the chalcogen injection at 340C, up to 44% Te incorporation is achieved in MoSe2-xTex. Detailed structural, chemical and optical investigation is used to identify the phase, polytype, chemistry and electronic states of the alloy. Also, the 2D-2D interface between graphene and chalcogenide films is studied to map rotational alignment, strain and mosaicity.
Engineering; alloy; epitaxy; exciton; GI-XRD; oxidation; Transition metal
Xing, Huili Grace
Materials Science & Engr
MS of Materials Science & Engr
Master of Science
dissertation or thesis