Topographic Mapping of the Quantum Hall Liquid Using a Few-Electron Bubble
G. Finkelstein,
1
P. I. Glicofridis,
1
R. C. Ashoori,
1
M. Shayegan
2
A scanning probe technique was used to obtain a
high-resolution map of the random electrostatic potential inside the
quantum Hall liquid. A sharp metal tip, scanned above a semiconductor surface, sensed charges in an embedded two-dimensional (2D) electron gas. Under quantum Hall effect conditions, applying a positive voltage
to the tip locally enhanced the 2D electron density and created a
"bubble" of electrons in an otherwise unoccupied Landau level. As
the tip scanned along the sample surface, the bubble followed
underneath. The tip sensed the motions of single electrons entering or
leaving the bubble in response to changes in the local 2D electrostatic
potential.
1 Department of Physics and Center for
Materials Science and Engineering, Massachusetts Institute of
Technology, Cambridge, MA 02139, USA.
2 Department
of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
