Objectives of this project are: (1) to expand basic knowledge of growth and property characterization of high-quality oxide semiconductor thin films and p-n heterostructures; (2) to systematically characterize electrical transport properties of the films and p-n heterostructures as a function of chemical doping, film thickness, bias applied, and temperature; (3) to fabricate model systems based on epitaxial single crystal films consisting of field effect transistor (FET) structures and develop a fundamental understanding of the effect of bias applied across the p-n junction on electrical transport properties and selective adsorption properties; and (4) to explore fabrication and characterization of more complex devices such as bipolar transistors with an exposed p-n junction. These devices offer the possibility of amplified electronic response to adsorption at exposed p-n junctions, which may provide a new level of control at the atomic and molecular level. The long-term goal is to develop a fundamental understanding of oxide-based semiconductor heterostructures suitable for the design of nanoengineered sorbents, tunable displays, catalytic materials, and chemical sensors. The understanding gained is expected to provide guidance for improvement of chemical selectivity and sensitivity, and provide a science base for the development of microelectronic devices for selective, tunable chemical sensing. The insights gained will be beneficial not only for advancing chemical sensor technology and for improving health and safety in society, but also impact the basic research and technology development of transparent electrodes for electronic and optical devices. Additionally, through collaboration with Ford, fundamental information that this project will provide may improve emissions control technology for lean-combustion engines. Thus, the intellectual and broader impact of the proposed research may reach well beyond the realm of chemical sensing. %%% This project addresses basic materials research issues in a topical area of materials science with technological relevance, and places emphasis on the integration of research and education. The research program provides excellent opportunities for hands-on experience in the use of sophisticated scientific equipment. Graduate and undergraduate students will be involved in the synthesis, processing, and characterization of electronic materials. The project integrates research with educational outreach which includes (1) creating a mechanism to expose materials research to high school minority students through the existing NASA SHARP Plus program at the University of Michigan, (2) involving undergraduates (particularly women and minority students) in research early in their careers, and (3) bringing the nano-world to the classroom through remote control of electron microscopes via the internet. It is planned to use this facility to demonstrate to a high school class, both live and via a virtual microscopy base, how materials can be manipulated at the atomic scale, and also to use this system for demonstrations to attract undergraduates to materials science and engineering. Students involved in this project will have the opportunity to learn film growth techniques, device fabrication, materials characterization, and to interact with high school students. This interdisciplinary education will provide students with special opportunities and a broad perspective valued in both industrial and academic research. ***
