This experimental research project focuses on application of a new imaging method, the Subsurface Charge Accumulation (SCA) microscope to the new physics in low-dimensional electronic systems. A primary example of such a system is the quantum Hall effect occurring in a buried two-dimensional electron gas. The SCA microscope permits very high resolution, about 0.1 micrometer, examination of such systems which are inside materials. The research topics being pursued include the quantum Hall effect, the 2D metal-insulator transition and also single impurities and electron traps in semiconductors. A key element of the ongoing work is to determine the correlation between the structures seen in SCA images of the quantum Hall liquid and features in the transport properties of the 2D system. A topic of interest also is the behavior of spin textures or "skyrmions" which exist around the n=1 Hall plateau. Estimates of the sizes for skyrmions and a possible skyrmion crystal place them easily within the range of SCA measurements. This research program is interdisciplinary in nature and involves graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. %%% This experimental basic research project focuses on application of a new imaging method, the Subsurface Charge Accumulation (SCA) microscope to the new physics in low-dimensional electronic systems. The new microscope allows imaging of electron charge distributions on a scale of about 0.1 micrometer. This resolution does not allow atoms to be seen, but does allow imaging of broader distributions of buried charge, which is of great importance in many semiconductor situations. A primary example of such a system is the quantum Hall effect occurring in a buried two-dimensiona l electron gas. The SCA microscope permits very high spatial resolution examination of such systems which are inside materials. The research topics being pursued include the quantum Hall effect, the 2D metal-insulator transition and also single impurities and electron traps in semiconductors. A key element of the ongoing work is to determine the correlation between the structures seen in SCA images of the quantum Hall liquid and features in the transport properties of the 2D system. A topic of interest also is the behavior of spin textures or "skyrmions" which exist around the n=1 Hall plateau. Estimates of the sizes for skyrmions and a possible skyrmion crystal place them easily within the range of SCA measurements. This research program is interdisciplinary in nature and involves graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. ***
