OSE Seminar by OSE General Chair, Dr. Daniel Feezell on Carrier Dynamics in Commercial-Grade InGaN/GaN Light-Emitting Diodes Using Small-Signal Electroluminescence

Departmental News

Daniel Feezell

Posted: January 19, 2024

Date: Thursday, January 25th, 2024

Time:  12:45 PM - 1:45 PM MST

Location: CHTM, Room 103 and Zoom


The carrier dynamics in InGaN/GaN light-emitting diodes (LEDs) are directly tied to their efficiency and maximum modulation speed, which are important metrics for solid-state lighting, displays, and optical communication. In this work, we measure the carrier dynamics of InGaN/GaN light-emitting diodes using small-signal electroluminescence (SSEL) methods. We specifically study the carrier dynamics of commercial-grade c-plane LEDs with various indium compositions, various deep-level defect densities, and various quantum well thicknesses.  A rate equation approach and associated small-signal circuit are used to model carrier injection, recombination in the active region, recombination in the cladding regions, and carrier escape. The model is fit to the measured optical frequency response (S21) and input impedance (S11) of the LEDs to extract the various carrier lifetimes, the carrier density, and the recombination rates. The results offer insight into the underlying causes of efficiency droop and the green gap and may inform application-specific device design strategies.



Daniel Feezell is a Professor and Regents’ Lecturer in the ECE Department and the Center for High Technology Materials at UNM. He is also General Chair of the Optical Science and Engineering (OSE) program. He received the Ph.D. degree in 2005 from the University of California Santa Barbara (UCSB). Prior to joining UNM, he was a Project Scientist in the Solid-State Lighting and Energy Center at UCSB and worked for Soraa. His research includes epitaxial growth and fabrication of group-III nitrides, high-efficiency and high-speed LEDs; nanoscale selective-area epitaxy, vertical-cavity surface-emitting lasers, and wide-bandgap power electronics. He has authored or co-authored over 150 journal and conference publications and holds more than 20 U.S. patents. Dr. Feezell received an NSF CAREER award in 2015 and a DARPA Young Faculty Award in 2013.  Dr. Feezell’s projects have been funded by DOE, DOD, DARPA, ARPA-E, NSF, DTRA, and the commercial sector.  He is a Senior Member of IEEE.