Galium Arsenide Nanostructures

Electrons can be trapped at the interface between gallium-arsenide and aluminum-gallium-arsenide. As quantum mechanics forbids any motion perpendicular to the interface, these electron truly live in a two-dimensional world. Applying a magnetic field perpendicular to the layer further restricts the quantum states and the physics becomes even more spectacular. For example, charge transport within the two-dimensional system becomes quantized -- a phenomenon known as the quantum Hall effect. Two-dimensional electron systems formed in gallium arsenide represent an ideal laboratory to study many-particle physics in lower dimensions.

CAI tunneling data


We have recently applied our charge imaging method to the GaAs/AlGaAs system employing a 3D to 2D tunneling geometry. Using this novel technique, we have obtained the first direct images of ordered electronic structure within the interior. We find that the application of a magnetic field can produce surprising and subtle density variations, shown as bright and dark bands in the figure to the left.
The schematic image has been Fourier processed to enhance the structure; the inset shows raw data. The data were acquired at a temperature of 270 mK and with a perpendicular magnetic field of 6.75 T. Click here for the paper.


Gallium Arsenide Papers:

Direct Observation of Micron-Scale Ordered Structure in a Two-Dimensional Electron System, I. J. Maasilta, Subhasish Chakraborty, I. Kuljanishvili, S. H. Tessmer, and M. R. Melloch, Phys. Rev. B 68, 205328, 2003.

Tunneling Images of a 2D Electron System in a Quantizing Magnetic Field, I. J. Maasilta, Subhasish Chakraborty, I. Kuljanishvili, S. H. Tessmer, and M. R. Melloch, Physica E 18, 167, 2003.

Modeling Subsurface Charge Accumulation Images of a Quantum Hall Liquid, S. H. Tessmer, G. Finkelstein, P. I. Glicofridis, and R. C. Ashoori, Phys. Rev. B 66, 125308, 2002; also published in Virtual Journal of Nanoscale Science & Technology, 6/13, 2002.

Imaging of Low Compressibility Strips in the Quantum Hall Liquid, G. Finkelstein, P. I. Glicofridis, S. H. Tessmer, R. C. Ashoori, and M. R. Melloch, Phys. Rev. B 61, R6323, 2000.

Imaging the Low Compressibility Strips Formed by the Quantum Hall Liquid in a Smooth Potential Gradient,, G. Finkelstein, P. I. Glicofridis, S. H. Tessmer, R. C. Ashoori, and M. R. Melloch, Physica E 6, 251, 2000.

Scanning Microscopes Probe Local Details of the Quantum Hall State, B. G. Levi, Physics Today (Search and Discovery) 51 (4), 17, 1998.

Subsurface Charge Accumulation Imaging of a Quantum Hall Liquid, S. H. Tessmer, P. I. Glicofridis, R. C. Ashoori, L. S. Levitov, and M. R. Melloch, Nature 392, 51-54 (1998); Nature 395, 724, 1998.