Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 34: Nitrides: Dots, rods, and structures
HL 34.1: Vortrag
Dienstag, 17. März 2015, 11:15–11:30, EW 201
Direct evidence of quantum dot emission from GaN islands nucleated at threading dislocations — •G. Schmidt1, S. Metzner1, C. Berger1, P. Veit1, G. Callsen2, J. Bläsing1, F. Bertram1, A. Dadgar1, A. Hoffmann2, A. Strittmatter1, and J. Christen1 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Institute of Solid State Physics, Technical University Berlin, Germany
We give direct evidence of quantum dot (QD) emission from nanometer-sized GaN islands nucleated in close proximity of threading dislocations (TDs) using cathodoluminescence spectroscopy performed in a scanning transmission electron microscope (STEM-CL).
The islands result from a GaN quantum well (QW) layer growth by metal-organic vapor phase epitaxy on AlN/sapphire templates. After deposition of few monolayers of GaN forming the QW layer a growth interruption without ammonia supply was applied prior to 40 nm of AlN cap layer growth.
We are able to spatially resolve cathodoluminescence between 220 nm and 300 nm from the nanometer-sized GaN islands nucleated in the close proximity of AlN TDs, which do not inhibit the luminescence. Very sharp emission lines with line widths below 500 µeV are measured confirming quantum dot like electronic properties within these islands. This full width at half maximum represents a state-of-the-art line width compared to Stranski-Krastanov grown wurtzite polar, non-polar, and zinc-blende GaN QDs as well as GaN QDs embedded in nanowires.