9307986 Yu Characterization of semiconductor structures with extremely high spatial resolution will be crucial for continued reductions in device size and for the development of advanced heterostructure devices. The development of scanning tunneling microscopy (STM) and related techniques has dramatically enhanced our ability to study properties of materials with atomic or near-atomic resolution. STM offers several advantages over other techniques, such as x-ray diffraction, transmission electron microscopy (TEM), and photoluminescence, that have been used to probe atomic- and near-atomic-scale properties of semiconductors. We propose to use cross-sectional STM to investigate the electronic and structural properties of novel semiconductor structures. STM and related techniques offer both very high spatial resolution and sensitivity to electronic structure, allowing us to explore, with nanometer resolution, characteristics such as band-edge energy and carrier concentration profiles, structure of epitaxially grown interfaces, alloy composition and structural order, and perhaps heterojunction band-edge discontinuities. Of considerable interest to us will be the investigation of relationships between structure and local electronic properties in alloys and at heterojunction interfaces. ***
