Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 68: Poster Session: GaN: devices & preparation & characterization; III-V semiconductors; Photonic crystals; Semiconductor lasers
HL 68.5: Poster
Wednesday, March 13, 2013, 16:00–20:00, Poster A
Effect of barrier height and indium composition on the internal quantum efficiency of (In)AlGaN multiple quantum well structures — •Nikolay Ledentsov Jr.1, Christoph Reich1, Frank Mehnke1, Christian Kuhn1, Tim Wernicke1, Tim Kolbe1, Neysha Lobo Ploch1, Jens Rass1, Viola Kueller2, and Michael Kneissl1,2 — 1Institute of Solid State Physics, Technische Universität Berlin, Hardenberg-str. 36, 10623 Berlin, Germany — 2Ferdinand-Braun-Institut, Gustav-Kirchhoff-str. 4, 12489 Berlin, Germany
We studied (In)AlGaN multiple quantum wells (MQWs) emitting in the UV-B spectral region with photoluminescence and electroluminescence spectroscopy. The internal quantum efficiency (IQE) was determined by temperature dependent measurements (5 K - 300 K). The quantum confined Stark effect (QCSE) was investigated by studying the shift of the emission energy with increasing excitation power density. In the first series, Al0.27Ga0.73N MQWs with different AlxGa1−xN barriers (0.32 < x < 0.67) were investigated. Increasing the Al content increased the IQE due to improved carrier confinement. A maximum of the IQE of 24 % at x = 0.4 was obtained. Further increase of the Al content in the barriers decreased the IQE due to a stronger QCSE. In the second series, quaternary InAlGaN QWs were investigated. Due to In incorporation, room temperature emission energy shifted from 4.3 eV to 3.9 eV. At low temperatures two peaks were observed. The lower energetic peak was attributed to In-rich clusters. Influence of the In segregation will be discussed.