Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 99: Gallium Nitride: Devices
HL 99.4: Vortrag
Freitag, 11. März 2016, 10:30–10:45, H17
Impact of Design on the Optical Polarization of AlGaN Quantum Well Deep UV Light Emitters — •Christoph Reich1, Martin Feneberg2, Martin Guttmann1, Frank Mehnke1, Tim Wernicke1, and Michael Kneissl1 — 1Technische Universität Berlin, Institut für Festkörperphysik, Berlin, Germany — 2Otto-von-Guericke-Universität Magdeburg, Institut für Experimentelle Physik, Magdeburg, Germany
Light emitting diodes in the deep ultraviolet spectral region are of significant interest for applications in a variety of fields. However, efficient light extraction is a challenging task for deep UV emitters due to the strong tendency for transverse magnetic (TM, E∥c) polarized emission at shorter wavelength. The emission pattern for TM-polarized light is in-plane and thus the light extraction of TM-polarized light through a (0001) surface is an order of magnitude weaker compared to transverse electric (TE, E⊥c) polarized light. The optical polarization of (0001) oriented AlGaN quantum wells shifts from TE to TM with increasing aluminum mole fraction due to a reordering of valence bands and changing oscillator strengths. Using k·p perturbation theory, the influence of strain, quantum well width, barrier height and composition on the optical polarization has been investigated. The theoretical model calculations showed that compressive strain in the growth-plane and barriers with high aluminum mole fraction are beneficial for enhanced TE-polarized emission. Based on these design parameters, dominant TE emission will be demonstrated at wavelengths as short as 240 nm.