We study the charge distribution in GaAs quantum well containing a two-dimensional electron gas (2DEG). We use the spectral line of the negatively charged exciton, X-, as an indicator for the presence of charge. The X- is formed in this system by binding of a photo-excited electron-hole pair to an "native" electron, hence its local photoluminescence intensity is proportional to the local charge density. Large spatial fluctuations in the luminescence intensity of the X- are observed. These fluctuations are shown to be due to electrons localized in the random potential of the remote ionized donors. We use these fluctuations to image the electrons and donors distribution in the plane. These studies also allow us to obtain a microscopic understanding of the exciton lineshape in the presence of a 2DEG.
- 1. G. Eytan, Y. Yayon, M. Rappaport, H. Shtrikman and I.
Bar-Joseph
Near-field
spectroscopy of a gated electron gas: A direct evidence for electron
localization.
Phys. Rev. Lett. 81, 1666 (1998).
- 2. G. Eytan, Y. Yayon, M. Rappaport, H. Shtrikman and I.
Bar-Joseph
Near-field spectroscopy of a gated electron
gas.
p. 1-18 in "Optical Properties of Semiconductor Nanostructures",
Editors: M. L Sadowski et al., NATO ASI Series, Kluwer Academic
Publishers, Netherlands, (2000).
- 3. G. Eytan, Y. Yayon, I. Bar-Joseph, and M. L. Rappaport
A
storage deware near-field scanning optical microscope
Ultramicroscopy, 83, 25 (2000).
- 4. Y. Yayon, M. Rappaport, V. Umansky, and I. Bar-Joseph
Excitonic
emission in the presence of a two dimensional electron gas: A
microscopic understanding
Submitted, Cond Mat 0011142.
|
|
