Understanding the Atomic Structure and Electronic Properties of Zinc Oxide Interfaces

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Technical. This project addresses structure, composition, chemical bonding, and electronic properties of defects (dislocations and dopants), film/substrate interfaces, and p-n junctions in un-doped and doped ZnO films. Specific tasks are: (1) growth and characterization of ZnO thin films with different types of dopants and p-n junctions; (2) atomic-scale characterization of structure and electronic properties of interfaces; (3) in situ study of the stability and response of crystal defects and interfaces to applied electric field using an STM/TEM holder for TEM/STEM in combination with HRTEM and EELS. The crystal defects and interfaces to be studied include dopants, dislocations, grain boundaries, film/substrate interfaces, and p-n junctions. A TEM with spherical aberration-corrected cold field emission gun will be utilized for these studies; it provides sub-Å resolution for imaging and a very bright electron probe with an energy spread of 0.3 eV for electron energy-loss spectroscopy. Extensive characterization of the atomic structure and nanoscale electronic properties of defects and interfaces will be emphasized. Understanding based on these results is expected to allow subsequent development of p-type ZnO material, desirable for electronic and optical devices--detectors, light-emitters, transparent thin FETs or spin-based devices. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having technological relevance. The project includes multifac-eted educational opportunities for students. Undergraduates will be incorporated into this re-search via senior theses and REU experiences. Both graduate and undergraduate students will become involved in multiple steps of the solution of interdisciplinary research objectives. The PI will run hands-on workshops (Microscopic World of Materials) each summer for gifted female and minority K-12 students at the University of Michigan through NASA's Summer High School Apprenticeship Research Program. This interdisciplinary education will provide students with a unique perspective expected to be helpful toward furthering their interest in industry and academic research.