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HL: Fachverband Halbleiterphysik

HL 8: Interfaces/ surfaces

HL 8.2: Vortrag

Montag, 25. Februar 2008, 14:15–14:30, EW 201

Nano- and atomic-scale potential fluctuations in two-dimensional semiconductors — •Sebastian Landrock¹, Ying Jiang¹, Kehui Wu², Enge Wang², Knut Urban¹, and Philipp Ebert¹ — ¹Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich — ²Chinese Academy of Science

As the size of semiconductor devices is shrinking, not only the positioning of dopants is challenging, but also the knowledge on nanoscale potential fluctuations induced by inhomogeneities and the discrete nature of dopant atoms is becoming most critical. Therefore, we used scanning tunneling microscopy to measure the magnitude and extent of local potential fluctuations in a two-dimensional semiconductor with atomic resolution. On the one hand, we were able to prove that the limit of a macroscopic description of local nanoscale potential fluctuations is about 6×10¹³ dopants/cm². On the other hand, we found significant deviations from a microscopic description based on screened Coulomb potentials only. The potential consists rather of the superposition of extended potential fluctuations, defined by the charge carrier distribution in the bands, and local deviations from the spatial average of the screened Coulomb potentials arising from electron-electron interactions.