Date of Graduation

Spring 2025

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Kartik Ghosh

Abstract

2D layered molybdenum oxide has attracted significant research interest due to its tuneable bandgap and diverse structural, chemical, electrical, and optical properties influenced by growth parameters and synthesis techniques. In this study, the effects of reduction annealing on the structural and electrical properties of few-layer MoO₃ thin films, deposited on Si/SiO₂ substrates via pulsed laser deposition, were investigated. X-ray diffraction revealed nanocrystalline structures with a preferred (020) orientation, reduction annealing produced highly crystalline orthorhombic α-MoO₃ with reduced unit cell volume. FESEM/EDS provided detailed analyses of microstructures and elemental compositions. Raman spectroscopy confirmed the orthorhombic structure, with characteristic peaks at 667, 820, and 995 cm⁻¹, corresponding to O-Mo-O and Mo=O vibrational modes. UV-Vis spectroscopy showed a bandgap reduction from 3.3 eV to 3.07 eV, enhancing conductivity through oxygen vacancies. Preliminary FET measurements demonstrated that the samples retained their semiconducting behaviour, with IDS vs VDS characteristics showing effective gate modulation with high mobility. This study is a small endeavor to extend the research in wide band gap insulating transition metal oxides and their integration into device-based applications.

Keywords

α-MoO₃, 2D materials, Raman, XRD, SEM, bandgap reduction, oxygen vacancies

Subject Categories

Atomic, Molecular and Optical Physics | Condensed Matter Physics | Engineering Physics

Copyright

© Sandipani Ghosh

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