Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 49: Poster II

HL 49.34: Poster

Thursday, March 27, 2003, 16:30–19:00, HSZ/P2

Modeling of the electron-wave diffraction by potential fluctuations in a 2DEG — •Elena G. Novik, Hartmut Buhmann, and Laurens W. Molenkamp — Physikalisches Institut der Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

The propagation of electrons in a two-dimensional electron gas (2DEG) is strongly affected by scattering potentials which originate from ionized remote donors. These potential fluctuations in the 2DEG plane have a long range character and are responsible for the quantum interference effects in the electronic transport [1]. Here, we present a quantum mechanical model based on the Green’s function method to calculate the transmission probability of an electron beam between two quantum point contacts. In order to reproduce experimentally observed interference patterns the potential fluctuations were modeled. Potential heights, sizes, shapes and location were used as fitting parameters. Moreover, back-scattering effects from scattering centers and structure boundaries as well as temperature broadening and electron-electron scattering effects were included. The fitting gives a good approach for the microscopic properties of the potential fluctuations within the 2DEG plane and demonstrates that electron propagation in a 2DEG can be used as a local probe for these potential fluctuations. The average size is determined to be of the order of 70-160 nm, and the strength is found to vary from values comparable to the Fermi energy to values significantly above, which corresponds to expected correlations of different donor states within the donor layer.

[1] J.J. Koonen, H. Buhmann and L.W. Molenkamp, Phys. Rev. Lett. 84, 2473 (2000).