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
Abstract
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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