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Proceedings Paper

Optical polarization of UV-A and UV-B (In)(Al)GaN multiple quantum well light-emitting diodes
Author(s): Tim Kolbe; Arne Knauer; Joachim Stellmach; Chris Chua; Zhihong Yang; Sven Einfeldt; Patrick Vogt; Noble M. Johnson; Markus Weyers; Michael Kneissl
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Paper Abstract

The optical polarization of the in-plane emission of c-plane oriented (In)(Al)GaN multiple quantum well light emitting diodes in the spectral range from 288 nm to 386 nm has been investigated by electroluminescence measurements. The intensity of transverse-electric polarized light relative to the transverse-magnetic polarized light decreases with decreasing emission wavelength. This effect is attributed to the different electronic band structures in the active region of the light emitting diodes. A changing aluminum and indium mole fraction in the (In)(Al)GaN quantum wells results in a rearrangement of the valence bands at the Γ-point of the Brillouin zone. For shorter wavelengths the crystal-field splitoff hole band moves closer to the conduction band relative to the heavy and light hole bands and as a consequence the transverse-magnetic polarized emission increases. Moreover, the in-plane polarization is shown to depend on the injection current. The correlation between the in-plane polarization and the injection current has been found to be different for light emitting diodes with InGaN and (In)AlGaN multiple quantum wells. The results highlight that polarization effects need to be considered when optimizing the light extraction from ultraviolet light emitting diodes in the (In)AlGaN materials system.

Paper Details

Date Published: 4 March 2011
PDF: 6 pages
Proc. SPIE 7939, Gallium Nitride Materials and Devices VI, 79391G (4 March 2011); doi: 10.1117/12.876132
Show Author Affiliations
Tim Kolbe, Technische Univ. Berlin (Germany)
Arne Knauer, Ferdinand-Braun-Institut für Höchstfrequenztechnik (Germany)
Joachim Stellmach, Technische Univ. Berlin (Germany)
Chris Chua, Palo Alto Research Ctr., Inc. (United States)
Zhihong Yang, Palo Alto Research Ctr., Inc. (United States)
Sven Einfeldt, Ferdinand-Braun-Institut für Höchstfrequenztechnik (Germany)
Patrick Vogt, Technische Univ. Berlin (Germany)
Noble M. Johnson, Palo Alto Research Ctr., Inc. (United States)
Markus Weyers, Ferdinand-Braun-Institut für Höchstfrequenztechnik (Germany)
Michael Kneissl, Technische Univ. Berlin (Germany)
Ferdinand-Braun-Institut für Höchstfrequenztechnik (Germany)


Published in SPIE Proceedings Vol. 7939:
Gallium Nitride Materials and Devices VI
Jen-Inn Chyi; Yasushi Nanishi; Hadis Morkoç; Joachim Piprek; Euijoon Yoon, Editor(s)

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