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Leo J. Schowalter
Research Professor of Physics
Education:
Ph.D., University of Illinois: Urbana-Champaign, 1981 (Physics)
M.S., University of Illinois: Urbana-Champaign, 1976 (Physics)
B.S. (summa cum laude), University of Idaho, 1975 (Physics and Mathematics)
Career Highlights:
Schowalter began his professional career at the GE Research and Development Center in Schenectady, N.Y. as a staff physicist in 1980. He joined Rensselaer in 1987 as an associate professor and was promoted to full professor in 1993. He served as associate director of the Center for Integrated Electronics and Electronics Manufacturing (now the Center for Integrated Electronics) from 1994 to 1997 and as chair of the Physics, Applied Physics, and Astronomy Department from 1997 to 2000. In addition to his professorial role, Schowalter is president and co-founder of Crystal IS, Inc., the only supplier of single-crystal AlN substrates for the nitride semiconductor industry.
Dr. Schowalter has been an active leader for several professional meetings, including serving as chair of the 1999 Gordon Research Conference on Thin Films and Crystal Growth Mechanisms and as meeting chair of the 1998 Spring Materials Research Society Meeting in San Francisco. He also has been a co-instructor for several tutorials at international meetings on nitride semiconductors.
Schowalter has published over 130 articles, co-edited four proceedings volumes, and served as associate editor of the Journal of Vacuum Science and Technology from 1995 to 1998. He holds two U.S. patents and has three patents pending. Schowalter was elected to the Sigma Xi Honor Society in 1981 and was a distinguished visiting scientist at NASA's Jet Propulsion Laboratory at the California Institute of Technology from 1989 to 1990.
Research Interests:
Schowalter's research involves molecular beam epitaxy, electron transport at interfaces, optical properties of semiconductors, and the growth of wide band gap semiconductors. These wide band gap materials have the potential to revolutionize such fields as high-density data storage, high-temperature circuits, high-power circuits, wireless communications, and flat-panel displays, if methods can be found to produce low-defect materials in commercial quantities. His group has successfully grown aluminum nitride crystals large enough to slice into semiconductor substrates, which can be used to grow wide band gap semiconductor materials for blue lasers or to fabricate blue and green light emitting diodes (LEDs).
His current projects include preparing AlN substrate surfaces for epitaxy, using chemical-mechanical polishing (CMP); characterizing AlN and other wide band gap semiconductor surfaces for defects and subsurface damage; and making optical measurements of absorption in AlN to determine impurity and other point defect concentrations. He also is working with atomic force microscopy measurements and electric potential measurements of carbon nanotubes, to determine the possibility of making self-assembled electrical connections and switches for future very large-scale integration (VLSI) chips.
His research is funded by the New York State Science and Technology Foundation, the Defense Advanced Research Projects Agency (DARPA), International SEMATECH, the New York Interconnect Focus Research Center, Air Force Office of Scientific Research (AFOSR), the Missile Defense Agency (MDA), and Crystal IS, Inc.
Selected Publications:
S.B. Schujman, R. Vajtai, S. Biswas, B. Dewhirst, L.J. Schowalter, and P. Ajayan “Electrical Behavior of Isolated Multiwall Carbon Nanotubes Characterized by Scanning Surface Potential Microscopy,” Applied Physics Letters, 81, 541, (2002).
J. Carlos Rojo, L.J. Schowalter, R. Gaska, M. Shur, M.A. Khan, J. Yang, and D.D. Koleske, “Growth and Characterization of Epitaxial Layers on Aluminum Nitride Substrates Prepared from Bulk, Single Crystals,” Journal of Crystal Growth, 240, 508, (2002).
R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M.S. Shur, J.C. Rojo, and L.J. Schowalter, “Deep-Ultraviolet Emission of AlGaN/AlN Quantum Wells on Bulk AlN,” Applied Physics Letters, 81, 4658, (2002).
E. Kuokstis, J. Zhang, Q. Fareed, J. W. Yang, G. Simin, M.A. Khan, R. Gaska, M. Shur, J.C. Rojo, and L.J. Schowalter, “Near-Band-Edge Photoluminescence of Wurtzite-Type AlN,” Applied Physics Letters, 81, 2755, (2002).
J.C. Rojo, G.A. Slack, K. Morgan, B. Raghothamachar, M. Dudley, and L.J. Schowalter, “Report on the Growth of Bulk Aluminum Nitride and Subsequent Substrate Preparation,” Journal of Crystal Growth, 231, 317, (2001).
“Epitaxial Growth of AlN and Al0.5Ga0.5N Layers on Aluminum Nitride Substrates,” L.J. Schowalter, Y. Shusterman, R. Wang, I. Bhat, G. Arunmozhi, and G.A. Slack, Applied Physics Letters, 76, 985, (2000).
C.A. Ventrice Jr., V.P. LaBella, G. Ramaswamy, H.P. Yu, and L.J. Schowalter, “Measurement of Hot-Electron Scattering Processes at Au/Si(100) Schottky Interfaces by Temperature-Dependent Ballistic Electron Emission Microscopy,” Physical Review B, 53, 3952-3959, (1996).
K. Yang and L.J. Schowalter, “Diffusion Length of Ga Atoms on GaAs(–1–1–1) Surface in the Reconstruction Growth Regime,” Applied Physics Letters, 64, 1641, (1994).
K. Yang, T. Anan, and L.J. Schowalter, “Strain in Pseudomorphic Films Grown on Arbitrarily Oriented Substrates,” Applied Physics Letters, 65, 2789, (1994).
W. Li, T. Anan, and L.J. Schowalter, “Nucleation of GaAs on CaF2/Si(111) Substrates,’’ Applied Physics Letters, 65, 595, (1994).
Contact:
(518) 271-7375 Ext. 109
schowal@rpi.edu
Home Page: http://www.rpi.edu/dept/phys/schowalt.html
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