Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Scanning probe methods)
O 35.17: Poster
Dienstag, 15. März 2011, 18:30–22:00, P3
Investigation of an operating resonant tunneling device by scanning tunneling spectroscopy — •Karen Teichmann1, Martin Wenderoth1, Rainer G. Ulbrich1, Klaus Pierz2, and Hans W. Schumacher2 — 1IV. Physikalisches Institut, Georg-August Universität Göttingen — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
A resonant tunneling diode structure in a three terminal setup was investigated by Cross-Sectional Scanning Tunneling Microscopy (STM) and Spectroscopy. We use a home built low temperature STM working under UHV conditions at 5 K, which allows applying a lateral voltage to the sample in addition to the usual tip-sample voltage. The diode structure was grown by molecular-beam epitaxy on a n+-doped GaAs (100) substrate and consists of self-assembled InAs quantum dots embedded in AlAs barriers (4 nm) each followed by undoped GaAs prelayers (15 nm) [1]. The samples are cleaved in UHV to obtain a clean and atomically flat (110) surface perpendicular to the diode-structure. I(V) spectroscopy measurements were done with different applied lateral voltages. The shift of the valence band offset can clearly be seen. Differential conductivity peaks are visible to the left and right of the heterostructure and are explained by tip induced states. The shift of these states with lateral voltage can give insight in the tip induced band bending, which is known to be prominent on the GaAs (110) surface [2]. We acknowledge financial support by the DFG SPP 1285.
[1] I. Hapke-Wurst, et al., App. Phys. Lett. 82, 1209 (2003)
[2] R.M. Feenstra, et al., J. Vac. Sci. Technol. B 5, 923 (1987)