Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: Poster Session III
HL 33.10: Poster
Mittwoch, 14. März 2018, 17:30–19:30, Poster F
Investigation of the optical polarization of AlGaN multiple quantum wells using photoluminescence spectroscopy — •Bettina Neuschulz1, Christoph Reich1, Johannes Enslin1, Baran Avinc1, Frank Mehnke1, Norman Susilo1, Christian Kuhn1, Tim Wernicke1, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin
The valence band order in AlGaN quantum wells (QW) is strongly effected by the aluminum mole fractions in QW (x) and barrier (y) as well as the QW width. This can lead to a switching of the polarization P=(TE−TM)/(TE+TM) of the emitted light from mainly transverse-electric (TE) to transverse-magnetic (TM). The symmetry and order of the respective valence bands can be probed by polarization resolved photoluminescence (PL) as the degree of optical polarization is directly linked to the valence band properties. Using PL spectroscopy, the optical polarization of the in-plane AlGaN QW emission at room temperature has been investigated, and in a systematic study, the aluminum mole fractions of the QWs and barriers as well as the QW width have been varied. Measurements show that for 1.5 nm thin Alx GaN/AlN QWs the degree of polarization is changing from 0.33 (TE) for x=0.6 to −0.13 (TM) for x=0.81. Using 2 nm wide QWs with x=0.6 and y=0.81 strongly TE polarized light P=0.7 can be obtained. The transition from TE to TM polarized emission has been observed at a wavelength of ∼ 240 nm in good agreement to simulations based on k· p -perturbation theory.