Published in J. Appl. Phys. 105, 093718 (2009).

Novel Contrast Mechanism in Cross-Sectional Scanning Tunneling Microscopy of GaSb/GaAs Type-II Nanostructures

R. Timm,1 R. M. Feenstra,2 H. Eisele,1 A. Lenz,1 L. Ivanova,1 E. Lenz,3 and M. Dähne1
1Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin, Germany
2Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
3Fachgebiet für Theoretische Elektrotechnik, Technische Universität Berlin, 10587 Berlin, Germany


Cross-sectional scanning tunneling microscopy results on GaSb quantum wells and dots in GaAs are found to exhibit a narrow, sharply defined contrast of the nanostructure at negative sample bias, but a smoothly broadened contrast at positive sample bias. This novel contrast mechanism is related to the specific type-II band alignment of GaSb/GaAs heterostructures in combination with tip-induced band bending. The corresponding model is quantitatively verified by numerical simulations of band bending and tunnel current profiles combined with calculations of cleavage- induced strain relaxation.

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