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HL: Fachverband Halbleiterphysik

HL 8: Transport: Quantum dots, quantum wires, point contacts I (organized by TT)

HL 8.14: Vortrag

Montag, 31. März 2014, 13:00–13:15, BEY 81

Fixing the Energy Scale in Scanning Tunneling Microscopy on Semiconductor Surfaces — Gerhard Münnich¹, •Andrea Donarini², Jascha Repp¹, and Martin Wenderoth³ — ¹Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany — ²Institute of Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany — ³IV. Physikalisches Institut der Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

In scanning tunneling experiments on semiconductor surfaces, the energy scale within the tunneling junction is usually unknown due to tip-induced band bending. Here, we experimentally recover the zero point of the energy scale by combining scanning tunneling microscopy with Kelvin probe force spectroscopy. With this technique, we revisit shallow acceptors buried in GaAs [1]. Enhanced acceptor-related conductance is observed in negative, zero, and positive band-bending regimes. An Anderson-Hubbard model is used to rationalize our findings, capturing the crossover between the acceptor state being part of an impurity band for zero band bending and the acceptor state being split off and localized for strong negative or positive band bending, respectively.
G. Münnich, A. Donarini, J. Repp, and M. Wenderoth, Phys. Rev. Lett. 111, 216802 (2013)