MRI-R2 : Acquisition for In Vacuo Characterization and Pb-VI MBE System Upgrades

Oklahoma State University Multispectral Laboratories, Stillwater OK

Investigators

Abstract

0959787 Barnes Oklahoma State U. Multispectral Laboratories Technical Summary: This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Lead based IV-VI semiconductor alloys are unique as a multifunctional material due to its unique and tunable optical, electronic, magnetic and thermoelectric properties. Pb-VI material development has been overshadowed by II-VI (HgCdTe) and III-V (InSb) for infrared (IR) sensors/detectors/imagers since the late 1970s. With the current use of two dimensional imaging focal plane arrays the IV-VI semiconductors are again the optimal choice for IR devices. They are tolerant of structural and point defects that typically limit yields of II-VI and III-V semiconductor materials. Also, there is currently considerable drive to develop the Pb-VI materials for high efficiency thermoelectric energy harvesting applications. Despite these major technical drivers in sensors and energy harvesting, research in advancing the understanding and quality of the Pb-VI material system is minimal at best. In this program we are pursuing the fundamental development of the materials by a cooperative effort between the University Multispectral Laboratory, Oklahoma State University and Amethyst Research Inc. Integration of in vacuo characterization equipment, including RHEED, RGA, XPS and AES, allows for immediate feedback to growth processes and semiconductor properties unhindered by the formation of oxides and contaminants that occurs when these surfaces are removed from vacuum. Basic research enabled by this acquisition includes understanding the band alignment between ternary Pb-VI alloys (to be immediately fed into device modeling efforts), understanding growth modes for Pb-VIs on II-VI/Si composite substrates and feedback during growth of semiconductor heterostructures for defect engineering/nanostructuring. These projects will lead to improved device design and subsequently enhanced energy harvesting and sensor performance. This effort places an emphasis on incorporation of graduate and undergraduate student research experiences, which in collaboration with small business also opens the door to cross-disciplinary cooperation in the academic environment as physicists, material scientists and electrical engineers understand, grow and design advanced device structures in the selected material system. Non-Technical Summary: This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). To enhance the understanding of basic material properties it is important to investigate the system in a pristine environment. By acquiring a number of specialized analysis tools designed to work in such an environment, basic research of Pb-salt based materials will be performed as part of a collaborative effort between the University Multispectral Laboratory, Oklahoma State University and Amethyst Research Inc. Investigation of Pb-salt based semiconductors addresses areas of societal concern in the security, health, energy and environmental sectors. These materials are far more tolerant of material issues that limit yields in other semiconductor systems. The research that will be performed provides the enabling technology to manufacture low-cost, high performance infrared imaging arrays, allowing advanced sensing to penetrate previously untapped markets such as non-military surveillance, infrared radiography for tumor and other medical imaging, and environmental monitoring. This material system is also a prime candidate for solid-state thermoelectric power devices that have the potential for significant economic and improved environmental impact to society by allowing harvesting of waste heat through direct conversion to electricity. The project will involve the training of undergraduate and graduate students in physics, electrical engineering and materials science in a vital technology, and also simultaneously involve and expose these students to high technology industry.