1. Research
  2. Publications
  3. Strain induced power enhanceme ...


Find scientific contributions

to conferences also on our events page.

Strain induced power enhancement of far-UVC LEDs on high temperature annealed AlN templates

A. Knauer1, T. Kolbe1, S. Hagedorn1, J. Hoepfner2, M. Guttmann1, H.K. Cho1, J. Rass1, J. Ruschel1, S. Einfeldt1, M. Kneissl1,2, and M. Weyers1

Published in:

Appl. Phys. Lett., vol. 122, no. 01, pp. 011102, doi:10.1063/5.0134253 (2023).


High temperature annealed AlN/sapphire templates exhibit a reduced in-plane lattice constant compared to conventional non-annealed AlN/sapphire grown by metalorganic vapor phase epitaxy (MOVPE). This leads to additional lattice mismatch between the template and the AlGaN-based ultraviolet-C light emitting diode (UVC LED) heterostructure grown on these templates. This mismatch introduces additional compressive strain in AlGaN quantum wells resulting in enhanced transverse electric polarization of the quantum well emission at wavelengths below 235 nm compared to layer structures deposited on conventional MOVPE-grown AlN templates, which exhibit mainly transverse magnetic polarized emission. In addition, high temperature annealed AlN/sapphire templates also feature reduced defect densities leading to reduced non-radiative recombination. Based on these two factors, i.e., better outcoupling efficiency of the transverse electric polarized light and an enhanced internal quantum efficiency, the performance characteristic of far-UVC LEDs emitting at 231 nm was further improved with a cw optical output power of 3.5 mW at 150 mA.

1 Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Institute of Solid State Physics, Technische Universit€at Berlin, Hardenbergstraße 36, 10623 Berlin, Germany


Quantum wells; Heterostructures; Light emitting diodes; Crystal structure; Quantum efficiency; Epitaxy; Semiconductors; Flip chip; Crystallographic defects

Copyright © 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0134253

Full version in pdf-format.