NSF Award
0102699
This project is devoted to the investigation of collective and localized excitations in tetrahedrally coordinated semiconductors and their heterostructures by means of a variety of optical techniques. The research will focus on the collective and localized excitations in isotopically controlled semiconductors composed composed of light atoms (diamond, SiC, BN and BP). Attention will be given to electronic states of donor-bound electrons and acceptor-bound holes in isotopically controlled diamond, Si, silicon carbide polytypes, as well as II-VI and III-V compound semiconductors. In addition, localized vibrations and gap modes of isoelectronic and compensated impurities will be explored and delineated in the chalcopyrites genealogically derived from the II-VI and III-V semiconductors. Collective excitations subjected to the constraints of the reduced dimensionality of nanostructures fabricated with molecular beam epitaxy will be investigated. Raman, Brillouin, Infrared , photoluminescence and modulated reflectivity/transmission spectroscopic techniques supplemented by piezo- and magneto-spectroscopy will be employed to address the above problems. Students will participate in this research. They will receive training in one of the forefront areas of current semiconductors physics and will thereby be prepared to enter the scientific/technical workforce of the 21st Century. <br/><br/>This research deals with the application of several experimental optical techniques to problems posed by advanced semiconductor materials. These materials play a great role in current technology but a basic understanding of their behaviors is still lacking. This research will provide information that will be useful for the synthesis and use of ultrahard materials, such as diamond, silicon carbide, boron nitride and others that have found applications as superhard thin film coatings. The behavior of these materials can be changed by the deliberate, controlled introduction of specific impurities or by manipulating their isotopic composition. The changed behaviors hold the promise of improved performance of the materials in applications of high temperature/high power electronic devices. This project offers many opportunities for the participation by students. Participants in the program will be exposed to the excitement and intellectual challenges of an area that is important in contemporary basic science and significant for potential applications. The expertise thus developed will prepare them for a future in academia and government as well as a career in research and development in the high tech optoelectronic industry.
