Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 31: Poster: Nitrides
HL 31.11: Poster
Montag, 31. März 2014, 17:00–20:00, P2
Morphology and atomic structure of GaN surfaces and InGaN/GaN quantum wells — •Sabine Alamé1, Andrea Navarro-Quezada1, Daria Skuridina2, Tim Wernicke2, Michael Kneissl2, Patrick Vogt2, and Norbert Esser1,2 — 1Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. — 2Technische Universität Berlin, Institut für Festkörperphysik, Germany
We present a study on the morphology and optoelectronic properties of buried group-III polar In0.11Ga0.89N and In0.07Ga0.93N single quantum wells (SQWs) upon (0001) surface preparation. The SQWs were grown in a GaN matrix by MOVPE on sapphire substrate, with thicknesses of 3 to 5 nm, the thicknesses of the GaN cap layers were varied from 1 to 10 nm. For the surface preparation the samples underwent thermal annealing between 400∘C and 800∘C under ultra high vacuum conditions and in nitrogen plasma. X-ray photoelectron spectroscopy revealed, that annealing up to 650∘C in nitrogen plasma ambient removes about 90 % of surface oxides and carbons from the oxidized surface without affecting the emission of the underlying SQW, as determined by photoluminescence spectroscopy. It was found, that the indium content of the QWs decreases, whereas the emission wavelength seems not to be changed within the error margin. Low energy electron diffraction showed a (2x2) surface symmetry for the annealed GaN (0001) cap layers, with an increasing surface order for higher annealing temperatures. Clean surfaces in combination with conserved optical properties of the SQWs serve as a starting point for further studies on the interaction of adsorbates with the SQW layers.