Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 46: III-V semiconductors: mainly wires and dots

HL 46.1: Talk

Tuesday, March 12, 2013, 15:00–15:15, H15

Cathodoluminescence spectroscopy of single GaN/AlN quantum dots directly performed in a scanning transmission electron microscope — •Frank Bertram¹, Gordon Schmidt¹, Markus Müller¹, Silke Petzold¹, Peter Veit¹, Jürgen Christen¹, Aparna Das², and Eva Monroy² — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — ²CEA/CNRS group Nanophysique et Semiconducteurs, INAC/SP2M, CEA-Grenoble, France

In this study we will present a nanoscale optical and structural characterization of a III-nitride based quantum dot (QD) heterostructure. A 1 µm thick AlN layer grown on a sapphire substrate using metal organic vapor phase epitaxy (MOVPE) serves as template for the further growth process. Subsequent, a stack of 10 GaN QD layers, each embedded in 50 nm thick AlN barrier, were grown under an optimized plasma-assisted molecular beam epitaxy process on an AlN-MOVPE/sapphire template. The cross-section high angle annular dark field image (HAADF) in a scanning transmission electron microscope (STEM) clearly reveals the GaN QD layers. The comparison of the HAADF image with the simultaneously recorded panchromatic cathodoluminescence mapping at 16 K exhibits a spot like luminescence distribution of the upper six QD layers solely, indicating no formation of the first four intentionally grown QD layers. Addressing a very few to single QDs we observe a broad luminescence between 3.0 eV and 4.0 eV originating from the superposition of the single emission lines.