| A Material World: | |
| Microelectronic Materials | |
Though silicon-based semiconductor technology is state-of-the-art today, there are many emerging applications for which silicon is not well suited. Among these are high-frequency, high-power amplifiers used in wireless telecommunications base stations; high-temperature electronics used in aircraft and automotive engines; and circuitry for the high-radiation environments of space flight and satellite systems.
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Novel materials hold great potential for meeting these needs, but understanding which materials offer the best performance in emerging applications is crucial. Dr. Kevin F. Brennan of the School of Electrical and Computer Engineering and his colleagues at the University of Minnesota have developed a novel theoretical technique for determining the ultimate limits of these new semiconductor materials in device structures.
Their approach, called materials theory-based modeling, is based on studying the fundamental properties of the materials from which a device is made. The essential properties that dictate the performance of a device are deduced from the study of the materials' fundamental behaviors under a variety of conditions.
Armed with this knowledge, Brennan and colleagues can predict — in advance of experimental measurements — how semiconductor devices made with new and unconventional, but promising, semiconductor materials will ultimately perform. This saves time and money on materials and device development.
With funding from the National Science Foundation and the Office of Naval Research, the researchers have examined the performance limits of transistors made with two important new semiconductor materials, gallium nitride and silicon carbide. They also have predicted how these materials will behave at very high applied voltages. These predictions were later confirmed by experimental measurements.
Meanwhile, other Georgia Tech researchers are characterizing the interfaces among the next generation of electronic materials. This information is important for device fabrication. In one particular project funded by the U.S. Air Force's Wright Laboratories, Drs. April Brown, Gary May and Z.L. Wang are using high-resolution transmission electron microscopy to study defects at the interfaces among junctions between dissimilar materials. These junctions, known as heterojunctions, form the basis for advanced microwave and millimeter wave electronic devices. The structures are fabricated by molecular beam epitaxy at Georgia Tech.
In other related work, the researchers are characterizing quantum dots — semiconductor material, about 25 nanometers in width, sitting on a substrate made of another material. Specifically, they are fabricating and characterizing heterojunctions and quantum dots fabricated from an array of materials, including gallium, indium, phosphorus and arsenic grown on a substrate of gallium arsenide.
The electrical and optical properties of heterojunctions and quantum dots are largely determined by level of perfection of the interfaces and the shape and configuration of the dots, which can be manipulated to achieve various results. So, examining interfacial defects among these materials can provide important information about their effects on electronic device fabrication.
— Jane M. Sanders
For more information, contact:
(1) Dr. Kevin Brennan, School of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0269. (Telephone: 404-894-6767) (E-mail: kevin.brennan@ee.gatech.edu;
(2) Dr. April Brown, School of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250. (Telephone: 404-894-5161) (E-mail: april.brown@ee.gatech.edu);
(3) Dr. Z.L.Wang, School of Materials Science and Engineering, Georgia Tech, GA 30332-0245. (Telephone: 404-894-8008) (E-mail: zhong.wang@mse.gatech.edu)
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