OSE Seminar by Professor Daniel Feezell on Nonpolar GaN-based VCSELs with lattice-matched nanoporous distributed Bragg reflector mirrors*

Departmental News

Professor Daniel Feezell 225 x 300

Posted: February 2, 2021

Date: Thursday, February 4, 2020 

Time:  11:00 AM to 12:00 PM

Location:  via Zoom

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GaN-based vertical-cavity surface-emitting lasers (VCSELs) have drawn interest in recent years for their potential applications in data storage, laser printing, solid-state lighting, optical communications, sensing, and displays. Several research groups have demonstrated electrically injected GaN-based VCSELs utilizing different growth and fabrication techniques to address the many challenges associated with III-nitride materials. One such challenge is fabrication of high-quality conductive epitaxial distributed Bragg reflectors (DBRs). A relatively new approach that yields high-index-contrast lattice-matched epitaxial DBRs is to introduce subwavelength air-voids (nanopores) in alternating layers of doped/undoped GaN. These nanoporous layers can be achieved by the controlled anodic electrochemical etching of highly doped n-type GaN in acids. The selective formation of the nanopores in the doped layers effectively lowers the refractive index compared to the adjacent undoped GaN layers, resulting in a refractive index difference of ~0.83, allowing high reflectance (>99%) with only ~16 pairs. Here, we will present electrically injected nonpolar m-plane GaN-based VCSELs with lattice-matched nanoporous GaN bottom DBRs and top dielectric DBRs. Lasing under pulsed operation at room temperature was observed at 409 nm with a linewidth of ~0.6 nm and a maximum output power of ~1.5 mW. The nonpolar m-plane orientation offers low transparency, high material gain, and anisotropic gain characteristics. The VCSELs were linearly polarized with a polarization ratio of ~0.94 and emission polarization-pinned along the a-direction. The mode profiles and thermal properties of the VCSELs will also be discussed.


Dr. Feezell is a Senior Member of IEEE. He has authored or co-authored over 150 journal and conference publications and holds more than 20 U.S. He received a Defense Advanced Research Projects Agency (DARPA) Young Faculty Award with a Director’s Fellowship Extension and a National Science Foundation Faculty Early Career Development (CAREER) Award. He received the Ph.D. degree in 2005 from the University of California Santa Barbara (UCSB) and was previously a Project Scientist in the Solid-State Lighting and Energy Center at UCSB and the first employee at Soraa. His research interests include epitaxial growth and fabrication of nonpolar and semipolar III-nitrides; high-efficiency and high-speed light-emitting diodes (LEDs); nanoscale selective-area epitaxy; vertical-cavity surface-emitting lasers (VCSELs); and wide-band-gap power electronics. Daniel Feezell is an Associate Professor in the Electrical and Computer Engineering Department at the University of New Mexico. He has authored or co-authored over 150 journal and conference publications and holds more than 20 U.S. patents.  Additional information can be found at http://www.feezellgroup.com

*Saadat M. Mishkat-Ul-Masabih1, Andrew A. Aragon1, Morteza Monavarian1, Ting S. Luk2, and Daniel F. Feezell1

1Center for High Technology Materials, University of New Mexico, Albuquerque, NM 87106, USA

2Center for Integrated Nanotechnologies, Albuquerque, NM 87185, USA