234 nm far-ultraviolet-C light-emitting diodes with polarization-doped hole injection layer
T. Kolbe1, A. Knauer1, J. Rass1, H.K. Cho1, S. Hagedorn1, F. Bilchenko2, A. Muhin2, J. Ruschel1, M. Kneissl1,2, S. Einfeldt1, and M. Weyers1
Appl. Phys. Lett., vol. 122, no. 19, pp. 191101, doi:10.1063/5.0143661 (2023).
Far-ultraviolet-C (far-UVC) light-emitting diodes (LEDs) with an emission wavelength of 234 nm with different polarization-doped AlGaN hole injection layers (HILs) are compared regarding their emission power, voltage, and leakage current. The influence of the thickness of the polarization-doped layer (PDL), an additional Mg doping of the PDL, as well as a combination of a PDL with a conventionally Mg-doped AlGaN HIL will be discussed. The different PDL thicknesses show nearly no influence on the emission power or voltage. However, the leakage current of the LEDs below the turn-on voltage decreases with an increasing thickness of the PDL. In contrast, an additional Mg doping of the PDL ([Mg] ∼ 1.5 × 1019 cm-3) results in a fivefold decrease in the emission power at an unchanged voltage and leakage current. Finally, a combination of a PDL and a conventionally Mg-doped AlGaN layer ([Mg] ∼ 1.5 × 1019 cm-3) as a HIL shows also a similar emission power and voltage compared to the single PDL, but the leakage current increases. Based on these optimizations, 234 nm LEDs were realized with a maximum external quantum efficiency of 1% at 20 mA, an emission power of 4.7 mW, and a voltage of 9.0V at 100 mA. This shows that the polarization doping concept is well suited to realize far-UVC LEDs with improved performance compared to LEDs with a conventionally Mg-doped p-side.
1 Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
2 Institute of Solid State Physics, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
© 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/10.1063/5.0143661
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