Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 80: GaN: Preparation and Characterization V (mainly Cathodoluminescence)
HL 80.7: Vortrag
Donnerstag, 29. März 2012, 12:45–13:00, ER 270
Optical and Structural Nano-Characterization of 62x InGaN MQW on GaN/AlInN DBR — •Marcus Müller1, Gordon Schmidt1, Peter Veit1, Thomas Hempel1, Frank Bertram1, Jürgen Christen1, Munise Cobet2, Raphaël Butté2, Jean-Françcois Carlin2, and Nicolas Grandjean2 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
Using low temperature cathodoluminescence spectroscopy (CL) directly performed in a scanning transmission electron microscope (STEM) we present optical and structural properties of a 62x InGaN multi quantum well (MQW) on top of a AlInN/GaN distributed Bragg reflector (DBR). The structure was grown by MOVPE on a sapphire substrate using an optimized GaN buffer.
Direct comparison of the STEM images with simultaneously recorded CL mappings resolve the complete layer sequence, especially the MQW. In particular, the DBR layer stack is laterally and vertically homogeneous with sharp AlInN/GaN interfaces. CL mappings of the DBR show a luminescence at 352 nm originating exclusively from AlInN layers.
A dominant emission with a broad spectral range of the InGaN MQW can be observed. Low temperature mappings (T < 20 K) exhibit a systematic redshift of the spectral position of the MQW from the bottom (410 nm) to the top (460 nm), indicating strain relaxation, higher indium incorporation, and/or increasing quantum well thickness.