Ms. Elizabeth DeJong, OSE PHD Student Showcased her Research at the UNM Shared Knowledge Conference

Departmental News

Ms. Elizabeth Dejong

Posted: November 3, 2022

Title:

An examination of InGaN micro-LED carrier dynamics through small signal RF analysis

Author(s):

Elizabeth DeJong, Doctoral Student, Optical Science and Engineering, UNM

Mr. Xuefeng Li

Dr. Daniel Feezell

Center for High Technology Materials (CHTM), University of New Mexico, Albuquerque, NM 87106, USA

Abstract: 

Light-emitting diodes (LEDs) are by far the most efficient and customizable light source commercially available. While large-area LEDs already have a wide range of uses and represent a massive decrease in energy costs and consumption compared to conventional light sources, applications such as directional lighting, digital displays, and visible light communication would benefit from a reduction in LED source size. Smaller light sources can achieve higher precision directionality, higher display resolution, and faster modulation. Micro-LEDs, usually defined as having a diameter of 50 μm or less, therefore have the potential to further reduce energy consumption and increase functionality. However, micro-LEDs currently suffer from a rapid drop in efficiency with decreasing diameter. While there are several factors that contribute to this size-dependent droop, the focus of our research has been characterizing and mitigating the detrimental effects of surface recombination due to sidewall damage during fabrication. Since the surface-area-to-volume ratio must increase as the diameter of the device decreases, any surface effects will more strongly affect small-area LEDs. To explore how surface recombination affects device operation, we have fabricated micro-LEDs with varying offsets and diameters, and treated a portion of our devices with KOH, which reduces sidewall damage induced during etching. By combining small-signal RF measurements with conventional DC testing, we are then able to extract the micro-LED carrier dynamics and relate the results to efficiency loss and the effectiveness of sidewall damage removal.

Biography

Elizabeth DeJong is currently a doctoral student in the Optical Science and Engineering program at the University of New Mexico (UNM). She earned her B.S. in physics from Haverford College, which she attended from 2014 to 2018. During that time, she conducted research in self-assembling, photoconductive nanorods, the properties of amorphous thin-film rubrene, and modelling and imaging complex quantum states. At UNM, she has worked with III-nitride semiconductor light-emitting diodes. Research topics have included the cause of the Green Gap in GaN based devices, and her current work focuses on the effects and mitigation of surface recombination in micro-LEDs. Her work has involved the fabrication of LEDs of varying sizes and geometries, as well as small-signal RF analysis combined with conventional DC testing to extract information on carrier dynamics.

Dr. Daniel Feezell's Research Group: 

Ms. Elizabeth DeJong is a doctoral student in the OSE program.  She is a member of Dr. Daniel Feezell, OSE General Chair's research lab. Dr. Feezell's present research interests include Optoelectronics, VCSELs, LEDs, epitaxial growth (MOCVD), and wide-bandgap materials


Link to Dr. Daniel Feezell's Research Group: 

Daniel Feezell III-Nitrides Research Group University of New Mexico (feezellgroup.com)


About the Poster Showcase:  

In the poster session, graduate students from programs across campus displayed their research in poster format and engage directly with conference attendees and fellow scholars. Research posters come in a wide variety of topics, crossing fields throughout the humanities and sciences. Poster evaluators are also on hand to provide feedback to presenters. Students are nominated by their academic program to display a research poster at the conference.

This year's Poster Showcase took place on Thursday, November 10th from 11:00 AM - 1:00 PM in the PAIS hallways. Finalists from the LoboBITES competition gave their presentations from 4:30 PM - 5:30 PM in the PAIS Auditorium. The Reception was from 5:30 PM - 6:30 PM in the lobby of PAIS.