Regensburg 2010 – scientific programme

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SYDI: Symposium SKM Dissertation Prize 2010

SYDI 1: SKM Dissertation Prize 2010

SYDI 1.2: Invited Talk

Tuesday, March 23, 2010, 14:00–14:30, H10

Nitrogen Containing III-V Semiconductor Surfaces and Nanostructures Studied by Scanning Tunneling Microscopy and Spectroscopy — •Lena Ivanova — Technische Universität Berlin, Institut für Festkörperphysik

Different nitrogen containing III-V semiconductor surfaces and nanostructures are studied using scanning tunneling microscopy and spectroscopy. In so-called diluted GaAsN layers single nitrogen atoms can be identified on the GaAs(110) cleavage surface. The measured density of states shows that nitrogen impurities lead to a splitting of the GaAs conduction band. The incorporation of nitrogen with a nominal concentration of 9% into InAs/GaAs quantum dots leads to a strong dissolution and the formation of extended spherical nitrogen-free InGaAs quantum dots with a low indium content. Furthermore, for the GaN(1100) cleavage surface of epitaxially grown GaN substrates it is found that both the nitrogen and gallium derived intrinsic dangling bond surface states are outside of the fundamental bulk band gap. The observed Fermi level pinning at 1.0 eV below the conduction band edge is attributed to the high step density, but not to intrinsic surface states. In GaN wafers dislocations are found to form localized bunches of entangled nonparallel dislocation lines. Within these bunches uncharged perfect dislocations with a/3⟨1120⟩ Burgers vectors and negatively charged Shockley partial dislocations with a/3⟨1100⟩ Burgers vectors interconnected by a negatively charged stacking fault are identified. Finally, an epitaxially grown silicon doping modulation structure is imaged.