Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: III-V semiconductors II
HL 33.2: Vortrag
Mittwoch, 27. Februar 2008, 14:30–14:45, EW 201
Optical studies on surface passivation by both wet-chemical sulfur treatment and epitaxial core-shell growth of GaAs Nanowires — •Steffen Münch1, Niklas Sköld2, Stephan Reitzenstein1, Johanna Trägardh2, Alexander Gorbunov1,3, Martin Kamp1, Lars Samuelson2, and Alfred Forchel1 — 1Technische Physik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — 2The Nanometer Structure Consortium, Lund University, 22100 Lund, Sweden — 3Institute for Solid State Physics, Russian Academy of Science, 142432 Chernogolovka, Russia
We report on the optical characterization of chemical and core-shell passivation techniques applied to GaAs nanowires (NWs). In particular, standard and time resolved micro photoluminescence (PL) spectroscopy was employed to investigate the effect of surface passivation on GaAs NWs. In case of GaAs surface passivation is of particular interest due to the large surface recombination velocity inherent to this material system. Chemical and core-shell passivation techniques were applied to GaAs NWs grown on a (111)B GaAs substrate using Au as catalysts. The core-shell NWs were realized by overgrowing a GaAs core in a MOVPE reactor with a 50 nm thick Al0.5In0.5P shell. Surface treatment results in an enhancement of free excitonic emission by a factor of about 40 and 110 for sulfur passivated and core-shell NWs, respectively. Furthermore, the effect of surface passivation is reflected in a strong reduction of the surface recombination velocity S to 2.5 x 104cm/s for the core-shell NWs compared to typical values of about 1 x 106cm/s reported for untreated GaAs NWs.