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Joan M.
Redwing
Professor
of Materials Science and Engineering; Chair, Intercollege Graduate Degree Program in Materials
Science and Engineering
101 Steidle Building
814-865-8665
redwing@matse.psu.edu
http://www.personal.psu.edu/faculty/j/m/jmr31/
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Biographical
Sketch:
Joan
M. Redwing received her B.S. in Chemical Engineering
from the University of Pittsburgh and her Ph.D. in Chemical
Engineering from the University of Wisconsin-Madison. She
was employed as a research engineer at Advanced Technology
Materials, Inc. from 1994-1999 working on metalorganic chemical
vapor deposition of group III-nitride materials. Dr.
Redwing joined the faculty of the Department of Materials
Science and Engineering at Penn State University in 2000. She
holds a joint appointment in the Department of Electrical
Engineering and is a member of the Materials Research Institute.
Dr. Redwing’s research interests are in the general
area of electronic materials synthesis and characterization
with a specific emphasis on semiconductor thin film and nanostructure
fabrication by chemical vapor deposition. She currently serves
as secretary of the American Association for Crystal Growth
and is an associate editor for the Journal of Crystal Growth. She
is a co-author on over 130 publications in refereed journals
and holds 8 U.S. patents. |
Research
Interests:
• Electronic
materials synthesis and characterization
• Metalorganic vapor phase epitaxy of compound semiconductors
• Wide bandgap materials (Group III-Nitrides and SiC)
• Semiconductor nanowire fabrication
• Gas phase and surface chemistry of epitaxial growth |
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Areas
of research:
Dr. Redwing’s research interests lie in the general
area of electronic materials processing and characterization
with a special emphasis on the vapor phase synthesis of semiconductor
thin films and nanostructures. An area of current focus
is the deposition of (Al,Ga,In)N thin films by metalorganic
chemical vapor deposition. These materials are used
in a wide variety of optoelectronic and high frequency, high
power devices including brightness blue/green light emitting
diodes, laser diodes, and high mobility transistors. Some
of the major difficulties associated with the epitaxial growth
of (Al,Ga,In)N layers and heterostructures are the large
lattice mismatches and thermal expansion coefficient mismatches
that exist between both the epitaxial layer and the substrate
and the different alloy layers in a heterostructure. These
mismatches produce stresses and defects in thin films that
are laterally constrained on a substrate. Thin film
stress plays an important role in determining the structural,
electrical and optical properties of (Al,Ga,In)N materials
and ultimately device performance, but the origin and evolution
of stress that arises during film deposition is not well
understood. In this work, in-situ laser reflectance
is used to measure growth rate and film stress in real time
during (Al,Ga,In)N growth in order to investigate the origin
of growth stress in (Al,Ga,In)N growth, study its impact
on material and device characteristics and develop methods
to control stress in these structures. Another area
of focus within the group is the synthesis of semiconductor
nanowires via vapor-liquid-solid growth, a process that utilizes
metal nanoparticles to promote axial wire growth from a gaseous
precursor. This research is focused on understanding
fundamental issues of crystallization, dopant incorporation,
alloy formation and heterostructure fabrication in nanowire
growth.
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Technologies
impacted by research:
Our
research on semiconductor thin films and nanostructures
impacts the electronics and optoelectronics industry. Compound
semiconductor thin films are the base materials used
to fabricate solid state lasers, high brightness light
emitting diodes and high performance transistors which
are used in communication, lighting and radar systems. |
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Journal
Articles and Publications:
1. “Structural and electrical properties of
trimethylboron-doped silicon nanowires,” K.K. Lew, L.
Pan, T.E. Bogart, S.M. Dilts, E.C. Dickey, J.M. Redwing, Y.
Wang, M. Cabassi and T.S.
Mayer, Appl. Phys. Lett. 85 (2004) p. 3101.
2. “Diameter-controlled synthesis of silicon nanowires
using nanoporous alumina membranes,” T.E. Bogart, S.
Dey, K.K. Lew, S. E. Mohney and J.M. Redwing, Adv. Mater. 17
(2005) p.
114.
3. “In-Situ Stress Measurements during MOCVD growth of
AlGaN on SiC,” J.D. Acord, S. Raghavan, D.W. Snyder and
J.M. Redwing, J. Cryst. Growth 272 (2004) p. 65.
4. “Intrinsic stresses in AlN layers grown by metalorganic
chemical vapor deposition on (0001) sapphire and (111)Si substrates,” S.
Raghavan and J.M. Redwing, J. Appl. Phys. 96 (2004) p. 2995.
5. “Enhancement of the superconducting transition temperature
of MgB2 by a strain-induced bond-stretching mode softening,” A.
V. Pogrebnyakov, J.M. Redwing, S. Raghavan, V. Vaithyanathan,
D.G. Schlom, S.Y. Xu, Qi Li, D.A. Tenne, A. Soukiassian, X.X.Xi,
M.D. Johannes, D. Kasinathan, W.E. Pickett, J.S. Wu and J.C.H.
Spence, Phys. Rev. Lett. 93 (2004) p. 147006. |
