Acceptor Doping and Hole Transport in ZnO Films and Heterostructures

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Technical. This project aims for greater understanding and control of p-type doping of ZnO. The project addresses phosphorus doping in epitaxial films on single crystal ZnO, phosphorus doping in non-polar ZnO films, co-doping ZnO with phosphorus and hydrogen, surface passivation, and formation and properties of ZnO pn homo- and heterojunctions. Characterization techniques, including temperature dependent Hall measurements, capacitance-voltage measurements, and low temperature photoluminescence, will be used to elucidate the behavior of phosphorus dopants in these materials. The overall objective of this project is to understand the synthesis and properties of ZnO-related pn homojunctions and heterojunctions in an effort to realize efficient p-type doping, minority carrier injection, and ultraviolet electroluminescence. Expected technological impacts include solid state lighting, thin film electronics and sensors. Understanding the doping of (Zn,Mg)O thin films will also be useful in the development of transparent conducting oxides, widely used as electrode materials in photovoltaic solar cells and light emitting displays. As wide band gap semiconductors, transparent conducting oxides are also attractive as active materials in transparent electric and optoelectronic technologies. Wide gap semiconducting oxides are attractive for transparent transistor development as they can be synthesized as thin films at lower temperatures that are compatible with various substrates, including glass. For chemical or biological sensors, the ability to fabricate pn junctions with ZnO-based materials opens the possibility of using the improved sensitivity of a high electron mobility transistor for sensor applications. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science and condensed matter physics having technological relevance. Basic understanding gained is expected to lead to improved device performance, and to allow design of new components. The project integrates research and education providing students with hands-on laboratory experience and training while conducting forefront research. Educational impacts include UF graduate and undergraduate students, as well as opportunities for outreach to local high school students. In order to address the need to educate engineering graduate students about the relative role of specific technologies to energy consumption, the project?s activities will also include providing a tutorial on Energy Consumption and Technologies to be delivered as part of the Graduate Student Seminar Series in Materials Science. In order to enhance the exposure of undergraduate students to wide bandgap semiconducting oxide research, the project will incorporate undergraduates through an existing Senior Research Thesis program. The research activities will involve a Ph.D graduate student. For both graduate and undergraduates involvement, persons from underrepresented groups (women, minorities) will be particularly encouraged to participate.