Date of Graduation

Fall 2025

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, & Materials Science

Committee Chair

Kartik Ghosh

Abstract

WO₃ thin films were characterized by being deposited on quartz and Si/SiO₂ substrates via Pulsed Laser Deposition method and then were exposed to reduction annealing in 5% H₂/95% Ar at 400°C for 1, 2, 10, and 15 hours. X-ray diffraction (XRD), Raman, UV-Vis, energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), and field-effect transistor (FET) showed that the 10-hour annealing is the best, as it is the only one that led to overall improvement in all properties. The quartz bandgap decreased from 3.20 to 2.91 eV transmittance while resistivity improved (238 → 0.0735 Ω·cm). The Si/SiO₂ resistivity was also improved by 2,349 times (119.8 → 0.051 Ω·cm). FET measurements, in turn, presented with dual conditions, where; 1 hour annealing presented a of electrons with a ratio of ON/OFF of 10⁴, and a 10-hour annealing proved ambipolar balance. The XRD analysis indicated the optimal crystallite size of 29.71 nm was reached at 10 hours, while the minimum microstrain and dislocation density were also present. Attributes beyond 10 hours went down mainly to oxygen back-diffusion from the substrate. This particular work demonstrates proper design tools for reduction-annealed WO₃ films in device applications.

Keywords

Thin-Films, Raman, UV-Vis, Reduction Annealing, Pulsed laser deposition, Oxygen vacancies, Bandgap, Electrical conductivity, SEM, AFM, MOSFET

Subject Categories

Electromagnetics and Photonics | Electronic Devices and Semiconductor Manufacturing | Materials Science and Engineering | Nanotechnology Fabrication | Other Materials Science and Engineering | Semiconductor and Optical Materials

Copyright

© Md.Zulkernain Haider

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Available for download on Friday, December 01, 2028

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