Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 17: Poster I

HL 17.38: Poster

Montag, 25. Februar 2008, 16:30–19:00, Poster D

Switching the Charge of a Single Mn-Dopant in InAs with the STM in Experiment and Model — •Felix Marczinowski, Focko Meier, Jens Wiebe, and Roland Wiesendanger — Institut für Angewande Physik, Universität Hamburg

We performed low-temperature scanning tunneling microscopy and -spectroscopy on Mn-doped InAs. We looked at (110) surfaces prepared by in-situ cleavage of InAs samples with Mn doping densities of 1*10¹⁷ cm⁻³ and 1*10¹⁹ cm⁻³. We find rings of increased differential conductance surrounding each Mn dopant with bias-voltage dependent diameter. When the ring crosses the acceptor, the well known anisotropic shape of the bound-hole wave function [1] appears in topographs. We take the rings as evidence for a charge-change of the acceptors caused by the tip-induced potential. A very simple Tersoff-Hamann based model, integrating the voltage dependent tip-induced quantum dot and the decharging, was used to accurately reproduce our observations. Our understanding allows interpreting the observed ring shapes as equipotential lines of the tip-induced quantum dot and the ring intensity as a direct measure for the screened Coulomb potential of the charged acceptor.

[1] Marczinowski, F.; Wiebe, J.; Tang, J.-M.; Flatté, M. E.; Meier, F.; Morgenstern, M. & Wiesendanger, R. ,Phys. Rev. Lett. 99, 157202 (2007)