This RUI project uses simultaneous, variable temperature cathodoluminescence (CL) and electron beam induced current (EBIC) to image transport properties, with micron scale resolution, in the near-contact region for a variety of high resistivity materials and devices. A new approach allows imaging of the motion of charge, in response to fixed-point generation. This approach is similar to CL in that an electron beam is used to generate charge, but different in two significant ways: the beam is not scanned during a given measurement and the collection of light allows for spatial resolution of the source of its emission. The motion of charge is tracked by detecting the light emitted along its path. Imaging will be used to view transport behavior, providing a new window on the transport of charge in the high field, highly non-uniform region adjacent to contacts, especially in high resistivity materials where space charge and internal fields play dominant roles over extended distances. Specific research goals include the study of charge transport patterns near contacts in SiC devices, improved understanding of contact performance and reproducibility in photorefractive heterostructures and direct imaging of electric field profiles in high energy radiation detectors. In addition, the technique has potential for directly observing fundamental changes in transport behavior in the near-contact region. A thermoelectrically cooled CCD will be used to image the light emitted in response to the point generation of charge in a semiconductor material. In standard CL, the spatial information of the emitted light is lost as the total emission signal is displayed as a function of position of the generation point. That information is maintained in this approach by using an internal optical microscope to collect and re-image the luminescence pattern. A magnification of ~ 1000-2000 x can be obtained, suggesting spatial resolution of the luminescence on the order of five microns or better, depending on generation conditions. %%% The project addresses fundamental research issues in a topical area of materials science having technological relevance. Undergraduate students will play a primary role in the project, with opportunities for research integrated directly into their academic program, and continued full time in the summer. The research program will also enable access to a state-of-the-art microanalysis facility for a wide variety of students, in addition to those engaged directly in the proposed project. An important feature of the project is the strong emphasis on education, and the integration of research and education. ***
