Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 26: Transport im hohen Magnetfeld/Quanten-Hall-Effekt
HL 26.8: Vortrag
Dienstag, 25. März 2003, 17:00–17:15, BEY/154
Scanning gate measurements in the quantum Hall regime at 300 mK — •Alessandro Pioda1, Slavo Kicin1, Thomas Ihn1, Tobias Vancura1, Klaus Ensslin1, Daniel D. Driscoll2, and Arthur C. Gossard2 — 1Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich — 2Materials Department, UCSB, CA 93106, USA
Scanning probe techniques allow the investigation of local electronic properties of semiconductor nanostructures. The goal is to achieve insight into the microscopic details of various physical effects, which is not accessible by conventional non-local magnetotransport measurements.
We report local scanning gate measurements on a 4 µm wide Ga[Al]As Hallbar with a 2-dimensional electron gas (2DEG) buried 34 nm below the surface. The measurements were performed scanning a conductive Pt-Ir AFM tip in feedback or in constant height mode over the surface of the sample. The longitudinal and transverse Hall resistance were measured as a function of tip position for various magnetic fields (0-9 T), tip to sample voltages and electron densities, at a temperature below 300 mK. We observe pronounced resistivity fluctuations as a function of the tip position. A strong correlation between images taken at filling factor ν and ν + n (n even-integer) is found. We also observe fine structure sized below 100 nm and concentric halos, centered on different positions of the Hallbar. Results will be discussed in the framework of the Landauer-Büttiker theory of transport.