Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 96: Poster III C (III-V Semiconductors incl. Nitrides)

HL 96.12: Poster

Thursday, March 19, 2015, 14:00–20:00, Poster B

Study of Optical Emission Properties of InGaN Quantum Wells on Semipolar (20-21) and (20-2-1) orientations — •Nikolay Ledentsov Jr.¹, Ingrid Koslow¹, Christian Mounir³, Tim Wernicke¹, Tore Niermann¹, Ulrich T. Schwarz³, Markus Weyers², and Michael Kneissl^1,2 — ¹TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany — ³Universität Freiburg, Georges-Köhler-Allee 106, 79110 Freiburg, Germany

Semipolar quantum wells (QW) exhibit polarized surface emission in contrast to polar QWs grown on the (0001) plane. This is caused by anisotropic and shear strain, leading to the mixing of the A,B and C valence bands. In this work we investigate the optical polarization of In_0.16Ga_0.84N and In_0.25Ga_0.75N 3.5nm single QWs grown on bulk GaN substrates with (20-21) and (20-2-1) orientation. Polarization resolved temperature- and excitation-dependent photo- (PL) and electro- (EL) luminescence measurements were performed on these samples. On (20-2-1) QWs we observe polarization ratios of 0.8-0.9 and band distances (ΔE) of 20-30meV at room temperature. These values agree with k · p simulations and literature. We found a strong dependency of ΔE on excitation power in PL measurement which could explain discrepancies between EL and PL measured ΔE values in the literature. (20-21) QWs exhibit low polarization ratios and do not correspond with k · p simulations, a trend observed by many groups. This discrepancy is addressed by TEM measurements and their interpretation in connection with the PL results.