ORCID ID

https://orcid.org/0000-0002-8454-4210

Date Awarded

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physics

Advisor

Rosa A Lukaszew

Committee Member

Dennis Manos

Committee Member

Mumtaz Qazilbash

Committee Member

Russell Wincheski

Abstract

There is a need for efficient ultraviolet (UV) detectors in many fields, such as aerospace, automotive manufacturing, biology, environmental science, and defense, due to photomultiplier tubes (the currently available technology) often not meeting application constraints in weight, robustness, and power consumption. In my thesis, I demonstrate that high quality vanadium dioxide (VO2) thin films, epitaxially grown on niobium doped titanium dioxide substrates (TiO2:Nb), display a strong photoconductive response in the UV spectral range, making them promising candidates for photomultiplier-free UV photodetection. By adjusting the characteristics of the substrate and VO2 film, the samples achieve external quantum efficiency exceeding 100% (reaching beyond 1,000% for optimized samples) superior to that of current wide band gap UV detectors at room temperature. The mechanism for photocurrent production in VO2/TiO2:Nb heterostructure is a space-charge region, engineered in the heterojunction, yielding favorable conditions for hole tunneling from TiO2:Nb into VO2. Improving upon the heterostructure, I demonstrate up to an order of magnitude improvement in parameters such as responsivity, external quantum efficiency, detectivity, and dark current density by applying Au films to the VO2/TiO2:Nb heterostructure. Ultimately, my work proved that the VO2/TiO2:Nb heterostructure is a promising alternative technology for UV detection in high demand fields, with great potential for scalable device production.

DOI

http://dx.doi.org/10.21220/s2-n2qw-v025

Rights

© The Author

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