We use a scanning capacitance probe to image transport in the quantum Hall system. Applying a DC bias voltage to the tip induces a ring-shaped incompressible strip (IS) in the 2D electron system (2DES) that moves with the tip. At certain tip positions, short-range disorder in the 2DES creates a quantum dot island in the IS. These islands enable resonant tunneling across the IS, enhancing its conductance by more than four orders of magnitude. The images provide a quantitative measure of disorder and suggest resonant tunneling as the primary mechanism for transport across ISs.
@article{arxiv.cond-mat/0506347,
title = {Imaging Transport Resonances in the Quantum Hall Effect},
author = {G. A. Steele and R. C. Ashoori and L. N. Pfeiffer and K. W. West},
journal= {arXiv preprint arXiv:cond-mat/0506347},
year = {2007}
}
Comments
4 pages, 4 figures, submitted to PRL. For movies and additional infomation, see http://electron.mit.edu/scanning/; Added scale bars to images, revised discussion of figure 3, other minor changes