Materials World Network: Engineering Electronic Structure with Extremely Mismatched Semiconductor Alloys

Completed

Other Power and Storage Technologies(Electric power conversion)
Other Power and Storage Technologies(Electricity transmission and distribution)

Basic and strategic applied research

PHYSICAL SCIENCES AND MATHEMATICS (Physics)
PHYSICAL SCIENCES AND MATHEMATICS (Metallurgy and Materials)

Not Cross-cutting

Dr S Novikov
Physics and Astronomy
University of Nottingham

Standard

EPSRC

01 June 2010

31 May 2013

36 months

£1

No relevance to Underpinning Sectors

East Midlands

Physical Sciences

Dr S Novikov, Physics and Astronomy, University of Nottingham

Dr RP Campion, Physics and Astronomy, University of Nottingham
Professor CT Foxon, Physics and Astronomy, University of Nottingham
Professor A Kent, Physics and Astronomy, University of Nottingham

This is a collaborative project between two groups from the University of California, Berkeley, USA and the University of Nottingham, UK, respectively. The objectives of the proposed program are aimed at massively engineering electronic structures of semiconductors for energy applications. The research to be undertaken targets fundamental questions in electronic materials research. Can electronic structures, not only bandgaps, of semiconductors be engineered at will for specific applications? What new properties would emerge if highly mismatched constituents are forcibly alloyed together at extremely off-equilibrium compositions? The broader objectives of this program are to train graduate student researchers in an internationally collaborative environment, and to transfer research innovations and concepts in new materials to the classroom. The specific research objectives of the project are to engineer electronic structure of highly mismatched semiconductor alloys at extreme compositions (eHMAs) and dope the eHMAs for innovative energy applications.Intellectual Merit. Specific electronic materials are used for particular physical processes in solid state energy conversion technologies. In most cases the energy conversion efficiency currently falls much below theoretical efficiencies. The blame is largely on the lack of materials with ideal electronic structures tuned for the specific physical process for the energy conversion. Here we propose a strategy for materials innovation in which two semiconductors highly mismatched in electronegativity are forced to be alloyed at extremely off-equilibrium compositions, thereby creating exotic electronic structures that would not be possible for currently existing materials and are widely tunable for various energy applications. These objectives, if achieved, would not only impact the basic science and engineering of materials from a new perspective, but also lay the foundation for a new generation of energy technologies.Broader Impacts. The promise of renewable energy technologies has captured the imagination of not only scientists, engineers and technologists but also the public at large. Materials research for energy applications provides exciting opportunities to engage future innovators in science and technology at all levels and in all nations. The proposed research and education program will provide invaluable training and opportunities for learning to graduate and undergraduate students. Graduate students will be exchanged between these two institutions to enrich their research experience and broaden their professional vision. The knowledge freshly gained in this research project will be introduced into an undergraduate class that the PI teaches. A molecular beam epitaxy expert at Nottingham will visit Berkeley once a year to give guest lectures in this class.The project will be executed as a collaborative effort between these two groups with expertise in materials growth and processingin the UK, and materials characterization and modeling in the USA, respectively. Achieving the proposed objectives is not possible unless pursued in the framework of our collaborations. We will employ low-temperature molecular beam epitaxy to grow the materials, and use laser annealing to process the materials. Comprehensive optical, electrical, microscopic and x-ray techniques will be used to characterize the materials. Numerical and analytical modeling will be performed to design the growth of materials and post-growth processing and explain the experimental data. Our preliminary results have achieved GaN1-xAsx over the entire composition range (0‹x‹1), forming the first ever eHMA. The project will take advantage of and benefit greatly from state-of-the-art research facilities on the U.C. Berkeley campus and the nearby Lawrence Berkeley National Lab (LBNL). Existing collaborations with LBNL scientists will be extended and enforced for full-aspect characterization of the eHMAs

11/11/11