Abstract

Deep-Ultraviolet (DUV) Light Emitting Diodes (LEDs) emitting invisible light at wavelengths below 280 nm, have seen increased research interest over the last decade. Of their many potential applications, pathogen neutralization is perhaps the most presently relevant in the post-COVID era. While the high energy light of DUV LEDs has been found particularly effective at destroying viruses and bacteria without the need for application of chemical agents, the poor efficiencies of DUV LEDs currently prevent their widespread adoption in these applications. While a number of factors contribute to the poor efficiency of DUV LEDs, light extraction is perhaps the most significant and difficult to address. The polarization of light emitted by DUV LEDs make it difficult to extract from the conventional “mesa” structures which form the overwhelming majority of LEDs. An alternative to mesas is to use arrays of closely spaced nano- or micro-structures connected in parallel, which have been shown both experimentally and by simulations to have significantly enhanced light extraction efficiency. In this work, the feasibility of using plasma etched arrays of nano- and micro-structures as alternatives to conventional mesa structures for emission of DUV light is investigated. New techniques for fabricating nanowire and micropillar array LEDs are developed, and a novel “inverse taper” crystallographic wet etch phenomenon which occurs in high Al-content AlGaN is discovered, described, and leveraged in device fabrication. The first reported demonstration of dry-etched, electrically driven, DUV emitting nanowire array LEDs is described in detail, in addition to the first demonstration of DUV emitting micro-LEDs based a novel AlGaN-delta-GaN active region previously design by our research group.

Library of Congress Subject Headings

Light emitting diodes--Industrial applications; Ultraviolet radiation; Nanowires; Plasma etching

Publication Date

6-18-2024

Document Type

Dissertation

Student Type

Graduate

Degree Name

Microsystems Engineering (Ph.D.)

Department, Program, or Center

Microsystems Engineering

College

Kate Gleason College of Engineering

Advisor

Jing Zhang

Advisor/Committee Member

Stefan F. Preble

Advisor/Committee Member

Seth M. Hubbard

Campus

RIT – Main Campus

Plan Codes

MCSE-PHD

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