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Tripling the light extraction efficiency of a deep ultraviolet LED using a nanostructured p-contact

E. López-Fraguas1, F. Binkowski2, S. Burger2,3, S. Hagedorn4, B. García-Cámara1, R. Vergaz1, C. Becker5 & P. Manley2,3,5

Published in:

Sci. Rep., vol. 12, art. 11480, doi:10.1038/s41598-022-15499-7 (2022).

Abstract:

Despite a wide array of applications, deep ultra-violet light emitting diodes offer relatively poor efficiencies compared to their optical counterparts. A contributing factor is the lower light extraction efficiency due to both highly absorbing p-contacts and total internal reflection. Here, we propose a structure consisting of a hexagonal periodic array of cylindrical nanoholes in the multi-layered p-contact which are filled with platinum. This nanostructure reduces the absorption of the p-contact layer, leading to a higher emission into the n-contact compared to a planar reference. An optimum geometry of the nanostructure allows a light extraction efficiency of 15.0%, much higher than the typical 4.6% of a planar reference. While the nanostructure strongly decreases the light absorption in the p-contact, it is still not able to considerably reduce the total internal reflection. Consequently, the nanostructured p-contact should be combined with other optical strategies, such as nanopatterned sapphire substrates to increase the efficiency even further. Despite this, the nanostructure described in this work provides a readily realizable path to enhancing the light extraction efficiency of state-of-the-art deep ultra-violet light emitting diodes.

1 GDAF-UC3M, Dep. Tecnología Electrónica, Universidad Carlos III de Madrid, Avda. Universidad, 30., 28911 Leganés, Madrid, Spain
2 Zuse Institute Berlin, Berlin, Takustraße 7, 14195 Berlin, Germany
3 JCMwave GmbH, Bolivarallee 22, 14050 Berlin, Germany
4 Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
5 Department Optics for Solar Energy, Helmholtz Zentrum Berlin für Materialen und Energie, Kekuléstr. 5, 12489 Berlin, Germany

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