Ultraviolet-B Resonant-Cavity Light-Emitting Diodes with Tunnel Junctions and Dielectric Mirrors
Journal article, 2024

We demonstrate the first electrically injected AlGaN-based ultraviolet-B resonant-cavity light-emitting diode (RCLED). The devices feature dielectric SiO2/HfO2 distributed Bragg reflectors enabled by tunnel junctions (TJs) for lateral current spreading. A highly doped n++-AlGaN/n++-GaN/p++-AlGaN TJ and a top n-AlGaN current spreading layer are used as transparent contacts, resulting in a good current spreading up to an active region mesa diameter of 120 μm. To access the N-face side of the device, the substrate is removed by electrochemically etching a sacrificial n-AlGaN layer, leading to a smooth underetched surface without evident parasitic etching in the n- and n++-doped layers of the device. The RCLEDs show a narrow emission spectrum with a full width at half-maximum (FWHM) of 4.3 nm compared to 9.4 nm for an ordinary LED and a more directional emission pattern with an angular FWHM of 52° for the resonance at 310 nm in comparison to ∼126° for an LED. Additionally, the RCLEDs show a much more stable emission spectrum with temperature with a red-shift of the electroluminescence peak of about ∼18 pm/K and a negligible change of the FWHM compared to LEDs, which shift ∼30 pm/K and show spectrum broadening with temperature. The demonstration of those devices, where a highly reflective mirror is spatially separated from an ohmic metal contact, opens up a new design space to potentially increase the poor light extraction efficiency in UV LEDs and is an important step toward electrically injected UV vertical-cavity surface-emitting lasers.

ultraviolet

AlGaN

electrochemical etching

tunnel junction

resonant-cavity light-emitting diode

Author

Estrella Torres

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Joachim Ciers

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Michael Alexander Bergmann

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Jakob Höpfner

Technische Universität Berlin

Sarina Graupeter

Technische Universität Berlin

Massimo Grigoletto

Technische Universität Berlin

Martin Guttmann

Ferdinand-Braun-Institut fur Hochstfrequenztechnik

Tim Kolbe

Ferdinand-Braun-Institut fur Hochstfrequenztechnik

Tim Wernicke

Technische Universität Berlin

Michael Kneissl

Technische Universität Berlin

Ferdinand-Braun-Institut fur Hochstfrequenztechnik

Åsa Haglund

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

ACS Photonics

2330-4022 (eISSN)

Vol. 11 8 2923-2929

Microcavity laser breakthrough for ultraviolet light (UV-LASE)

European Commission (EC) (EC/H2020/865622), 2020-08-01 -- 2025-07-31.

Ultravioletta och blå mikrokavitetslasrar

Swedish Research Council (VR) (2018-00295), 2019-01-01 -- 2024-12-31.

Subject Categories

Other Physics Topics

Condensed Matter Physics

DOI

10.1021/acsphotonics.4c00312

More information

Latest update

9/23/2024