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TIMOTHY H. GFROERER
Department of Physics,
Box 7133 Davidson College, 209 Ridge Road Davidson, NC 28035 office: (704) 894-2319, fax: (704) 894-2894 email: tigfroerer@davidson.edu, website: http://webphysics.davidson.edu/faculty/thg/
Education
Ph.D. in Physics (1996) Dartmouth,
Hanover, NH
Thesis Topic:
Magneto-spectroscopy of semiconductor nanostructures
M.S. in Electrical Engineering (1991) Georgia Tech, Atlanta, GA
Fields of Study:
Electromagnetics, Applied Optics, and Semiconductor Devices
B.S. (FBK, summa cum laude) in Physics (1989) University of the
South, Sewanee, TN Teaching Experience
Davidson College (1999-2004) Assistant and (2004-Present) Associate Professor of Physics Developed and team-taught a new interdisciplinary course on Philosophical Issues in Modern Physics with Philosophy Professor David Robb converted instrument/computer interfacing to the LabVIEW environment and initiated a wide variety of new experiments on nonlinear mechanical and electrical oscillators, statistical mechanics with squiggle balls, thermal distributions in semiconductor devices, fiber optics, and quantum entanglement Taught Modern Physics, introduced a new experiment on semiconductor quantum wells Taught senior-level Statistical and Thermal Physics Taught Intermediate Classical Mechanics, created an instructional set of Physlet-based oscillation simulations Taught Mathematical Methods for Scientists
with
an emphasis on applications in biology, chemistry, and physics Taught Introductory Physics II using a wide variety of instructional techniques including: web-based pre-class exercises, in-class group exercises, interactive Physlet problems, clickers, and traditional and computer-simulated in-class demonstrations Led a group study course for nonscientists on Concepts in Modern Physics Taught Introductory Physics Laboratory I and II, converted Laboratory II simulation exercises to Physlet format and developed a new set of Physlet-based special relativity exercises
James Madison University (1998-1999) Assistant Professor of Physics Taught
Physics, Chemistry, and the Human Experience (general education physical science) Taught Principles of Physics with Biological Applications II
Planned
for an upper-level course in Applied Optics
Red Rocks Community College (1997) Adjunct Instructor
Taught
algebra-based Introductory Physics II
Dartmouth College (1991-1996) Dartmouth Teaching Fellow Supervised
students in advanced laboratory courses Created
and led a supplemental instruction program for introductory physics students
Taught
introductory physics laboratory Research Interests Spectroscopic investigations of semiconductors with application to photovoltaic devices. Experimental techniques include excitation, temperature, and time-dependent measurements of photoluminescence and capacitance.
Research Experience National Renewable Energy Laboratory (2004-2005) Visiting Senior Scientist Host: Research Fellow Richard K. Arhenkiel
Davidson College
(1999-Present)
Assistant/Associate Professor of Physics Research Advisees: Emmett Weindruch ( '01), Laura Cupples ('02), Malu Fairley (Spelman '03), Patten Priestley ('03), Peter Campbell ('03), Kiril Simov ('05), Colleen Gillespie ('06), Peter Simov ('08), Adam Topaz ('08), Brant West ('08), Mac Read ('10), Dan Hampton ('11), KyungTaek Lim ('11)
JILA
[University of Colorado and National
Institute of Standards and Technology]
(1996-1998)
Research Associate, Postdoctoral Advisor: Nobel Laureate Eric A. Cornell
Dartmouth College (1992-1996) Graduate
Research Assistant
Thesis Advisor:
Professor Michael D. Sturge
Georgia Tech Research Institute
[GTRI] (1989-1991) Graduate Research Assistant
Research Advisor: GTRI Director James C. Wiltse
External GRANTS 2007-2010 Exploring defect level position and occupation in metamorphic heterostructures for multi-junction photovoltaic converters, American Chemical Society - Petroleum Research Fund, $55,000. 2004-2005 Connecting the electronic properties of defect states with underlying (sabbatical) structural features in lattice-mismatched InGaAs/InAsP heterostructures,
American Chemical Society - Petroleum Research Fund, $41,300. 2002-2006 Temperature-dependent carrier trapping and recombination in InGaAs/InAsP heterostructures lattice-mismatched to InP Substrates, American Chemical Society - Petroleum Research Fund, $50,000. 1999-2001 Absolute measurements of radiative efficiency in lattice-mismatched InGaAs/InAsP heterostructures, Research Corporation, $35,000. 1999-2001 Absolute measurements of radiative efficiency in lattice-mismatched InGaAs/InAsP
heterostructures, American Chemical Society - Petroleum Research
Fund, $25,000.
service and outreach Coordinator, Davidson College Physics Department Seminar Series, (2001-Present) Member, Local Organizing Committee for the Spring 2008 NC-AAPT Meeting and Host, 2008 Visit by David Mermin to Davidson College Expert panelist, Radio discussion on Solar Energy (WFAE Charlotte Talks, 2006) Facilitator, Davidson Outdoors Challenge Course: groups facilitated include Public Safety, Dining Services, Residence Life, Admissions, Student Government, International Students, and Freedom School Servant Leader Interns Member, Davidson College Ethnic Diversity Committee (2005-Present) Member, 2005 (Inaugural) and 2007 International Sturge Prize Committees Member, Davidson Academic Advising and Campus Safety Committees (2000-2004) Invited Specialist, 2004 and 2005 Planning Meetings for the Univ. of Hawaii Free Electron Laser Host, 2003 Smith Lecturer Nobel Laureate Eric Cornell Organizer, 2003 Davidson College Joint Science Student Research Symposium Member, 2002 Faculty-Staff Retreat and 2002 Lilly Sophomore Retreat Planning Committees
Judging Coordinator, 1999
Shenandoah Valley Regional Science Fair and 1999 Virginia Junior Science and Humanities Symposium Referee / Reviewer, Physical Review Letters, Physical Review B, Optics Communications, Semiconductor Science/Technology, Research Corporation and the Petroleum Research Fund
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Publications
(with
student collaborators in red)
Squiggle Ball capture: a simple, visual kinetic theory experiment, Tim Gfroerer and Ken Rathbun, The Physics Teacher 45, 344 (2007). Download pdf file.
Using the excitation-dependent radiative efficiency to assess asymmetry in the defect-related density of states, A. Topaz (Davidson '08), B.A. West (Davidson '08), T.H. Gfroerer, and M.W. Wanlass, Applied Physics Letters 90, 092110 (2007). Download pdf file.
Band-to-band and sub-bandgap cathodoluminescence from GaAsP/GaInP epistructures grown on GaAs substrates, T.H. Gfroerer, M.J. Romero, M.M. Al-Jassim, and M.W. Wanlass, Journal of Luminescence 122-123, 348 (2007).
Recombination in low bandgap InGaAs, T.H. Gfroerer and M.W. Wanlass in Proceedings of the 4th World Conference on Photovoltaic Energy Conversion (IEEE, 2006) pp. 780-782. Download pdf file.
Deep donor-acceptor pair recombination in InGaAs-based heterostructures grown on InP substrates, T.H. Gfroerer, C.E. Gillespie (Davidson '06), J.P. Campbell (Davidson '03), and M.W. Wanlass, Journal of Applied Physics 98, 093708 (2005). Download pdf file.
Observation of an anomalous minority carrier trap in n-type InGaAs, T.H. Gfroerer, K.R. Simov (Davidson '05), and M.W. Wanlass in Indium Phosphide and Related Materials (IEEE, 2005), pp. 657-659. Download pdf file.
Temperature dependence of nonradiative recombination in low-bandgap InGaAs/InAsP double-heterostructures grown on InP substrates, T.H. Gfroerer, L.P. Priestley (Davidson '03), M.F. Fairley (Spelman '03), and M.W. Wanlass, Journal of Applied Physics 94, 1738 (2003). Download pdf file.
Defect-related density of states in low-bandgap InGaAs/InAsP double heterostructures grown on InP substrates, T.H. Gfroerer, L.P. Priestley (Davidson '03), F.E. Weindruch (Davidson '01), and M.W. Wanlass, Applied Physics Letters 80, 4570 (2002). Download pdf file.
Photoluminescence (PL) in analysis of surfaces and interfaces, Timothy H. Gfroerer in the Encyclopedia of Analytical Chemistry, edited by R.A. Meyers (John Wiley and Sons, Chichester, 2000), pp. 9209-9231. Download pdf file.
Efficient directional spontaneous emission from an InGaAs/InP heterostructure with an integral parabolic reflector, T.H. Gfroerer, E.A. Cornell, and M.W. Wanlass, Journal of Applied Physics 84, 5360 (1998).
Progress towards laser cooling in semiconductors, T.H. Gfroerer, E.A. Cornell, and M.W. Wanlass in Radiative Processes and Dephasing in Semiconductors, edited by D. Citrin (Optical Society of America, Washington, 1998), pp. 39-42.
External radiative efficiency of 96% from a
GaAs/GaInP heterostructure,
H. Gauck, T.H. Gfroerer, M.J. Renn,
E.A. Cornell, and K.A. Bertness, Applied Physics A 64, 143
Slow relaxation of excited states in strain-induced quantum dots,
T.H. Gfroerer, M.D. Sturge, K. Kash, J.A.
Yater, A.S. Plaut, P.S.D. Lin, L.T. Florez, J.P. Harbison,
Magneto-spectroscopy of GaAs/AlGaAs strain-induced quantum wires and
dots,
The diamagnetic shift of excitons in strain confined quantum wires and
dots,
Further comments on Modes of elliptical waveguides: a correction, J.C. Wiltse and T.H. Gfroerer, IEEE Transactions on Microwave Theory and Techniques 40, 175 (1992).
Meeting Contributions
(with
student collaborators in red)
Defect-related trapping and recombination in metamorphic GaAs0.72P0.28 grown on GaAs, Tim Gfroerer, Peter Simov ('08), Brant West ('08), and Mark Wanlass, Photovoltaic Specialists Conference in San Diego, CA (2008). Download Poster.
Reciprocal capacitance transients? Tim Gfroerer, Peter Simov ('08), and Mark Wanlass, American Physical Society March Meeting in Denver, CO (2007). Download Presentation.
Thermally activated reciprocal capacitance transients in a GaAsP diode, Peter Simov ('08), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2006). Download Poster.
Modeling defect level occupation for recombination statistics, Adam Topaz ('08) and Tim Gfroerer, Southeastern Section of the American Physical Society Meeting (2006). Download Presentation.
Thermally activated radiative efficiency enhancement in a GaAs/GaInP heterostructure, Brant West ('08), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2006). Download Poster.
Recombination in low bandgap InGaAs, T.H. Gfroerer and M.W. Wanlass, World Conference on Photovoltaic Energy Conversion in Waikoloa, HI (2006). Download PowerPoint Presentation.
Squiggle Ball capture: a novel, visual thermodynamics experiment, Tim Gfroerer, Ken Rathbun, Kiril Simov ('05), and Blair Reynolds ('05), American Association of Physics Teachers Winter Meeting in Anchorage, AK (2006). Download PowerPoint Presentation.
Band-to-band and sub-bandgap cathodoluminescence from GaAsP/GaInP epistructures grown on GaAs substrates, T.H. Gfroerer, M.J. Romero, M.M. Al-Jassim, and M.W. Wanlass, International Conference on Luminescence in Beijing, CHINA (2005). Download PowerPoint Presentation.
Time-resolved photoluminescence spectroscopy of InGaAs/InP heterostructures, Colleen Gillespie ('06), Tim Gfroerer, and Mark Wanlass, Zone 5 (NC and SC) Meeting of the Society of Physics Students (2004). Download PowerPoint Poster.
Temperature-dependent transient capacitance in InGaAs/InAsP-based diodes, Kiril Simov ('05), Tim Gfroerer, and Mark Wanlass, American Physical Society March Meeting in Montreal, CANADA (2004). Download PowerPoint Presentation.
Physlet-based special relativity exercises for introductory laboratory, Tim Gfroerer, Mario Belloni, and Wolfgang Christian, American Physical Society March Meeting in Montreal, CANADA (2004).
Excitation dependence of sub-bandgap photoluminescence from InGaAs/InAsP heterostructures, Colleen Gillespie ('06), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2003). Download PowerPoint Poster.
Sub-bandgap photoluminescence in InGaAs/InAsP heterostructures lattice-mismatched to InP substrates, Peter Campbell ('03), Tim Gfroerer, and Mark Wanlass, American Association of Physics Teachers Winter Meeting in Austin, TX (2003). Download PowerPoint Presentation.
Physlet-based harmonic oscillation simulations for intermediate-level classical mechanics, Tim Gfroerer and Mario Belloni, American Association of Physics Teachers Winter Meeting in Austin, TX (2003).
Design, development, and testing of a transient capacitance spectroscopy system, Kiril Simov ('05) and Tim Gfroerer, North Carolina Section of the American Association of Physics Teachers Fall Meeting (2002). Download PowerPoint Presentation.
Incorporating Just-in-Time-Teaching into the Introductory Physics Laboratory, Larry Cain, Mario Belloni, Dan Boye, Wolfgang Christian, Tim Gfroerer, and John Yukich, American Association of Physics Teachers Summer Meeting in Boise, ID (2002).
Novel materials for heat-based solar cells, L.P. Priestley (Davidson '03), T.H. Gfroerer, M.F. Fairley (Spelman '03), and M.W. Wanlass, competitively selected Council on Undergraduate Research Posters on Capitol Hill in Washington, DC (2002).
Optics in the Intermediate Laboratory Course at Davidson, Tim Gfroerer, Charlotte Optical Society of America Chapter Meeting (2001).
Excitation-dependent transition between defect-related and radiative recombination in lattice-mismatched InGaAs/InAsP heterostructures, F.E. Weindruch (Davidson '01), T.H. Gfroerer, and M.W. Wanlass, American Physical Society March Meeting in Seattle, WA (2001).
Absolute measurements of radiative efficiency in light-emitting materials, Tim Gfroerer, SPIE Southeast Regional Meeting on Optoelectronics, Photonics, and Imaging (2000).
Construction and characterization of a laser diode assembly for
semiconductor spectroscopy, T.J. Nagle (James
Madison '01) and T.H. Gfroerer, Best Student Paper Award at the Annual
Beam control in light emitting diodes with integral
reflectors, T.H. Gfroerer,
Increasing the external radiative efficiency of
InGaAs/InP heterostructures,
Hot luminescence from
GaAs/AlGaAs strain-induced quantum dots, T.H. Gfroerer,
Picosecond magneto-luminescence from
GaAs/AlGaAs strain confined
quantum wires and dots, T.H. Gfroerer, M.D.
Sturge, K. Kash, J.A. Yater, A.S. Plaut, P.S.D. Lin, L.T. Florez, J.P. Harbison,
S.R. Das, and L. Lebrun, American Physical Society March
Errors in solutions for waveguides of elliptical cross-section, J.C. Wiltse and T.H. Gfroerer, Sixteenth International Conference on Infrared and Millimeter Waves in Lausanne, SWITZERLAND (1991).
Invited Talks and Seminars
Tricks and traps in the latest record efficiency solar cells, Appalachian State Physics Colloquium (February 22, 2008).
Solar cells, sluggish capacitance, and a puzzling observation, Colorado School of Mines Physics Colloquium (April 19, 2005) and Davidson College Physics Seminar (January 19, 2006).
Looking inside hidden excitons with THz radiation, Terahertz Workshop in Hololulu, HI (January 13, 2005).
Recombination and trapping in InGaAs/InAsP heterostructures, National Renewable Energy Laboratory in Golden, CO (October 8, 2004).
Optically-detected THz resonance spectroscopy of InGaAs, 2004 Terahertz Workshop in Honolulu, HI (January 16, 2004).
Why Sleep? Summer in Denali National Park ALASKA, Davidson Outdoors Into the Woods Week (February 19, 2003).
Optical properties of lattice-mismatched semiconductors for thermophotovoltaic cells, Jiao Tong University in Shanghai, CHINA (June 20, 2001).
Trail Magic: Through-Hiking the Appalachian Trail, Davidson Outdoors Into the Woods Week (February 23, 2001).
Shedding light on semiconductor misfits, James Madison University (November 13, 1998) and Davidson College (February 9, 1999).
The in's and out's of light in semiconductors, SUNY Geneseo (March 6, 1998), West Virginia Wesleyan College (March 13, 1998), and Berry College (March 27, 1998).
Progress towards laser cooling in semiconductors, Optical Society of America Meeting on Radiative Processes and Dephasing in Semiconductors in Coeur d'Alene, ID (February 3, 1998).
Hot pursuit of laser cooling in semiconductors, National Institute of Standards and Technology (May 21, 1997).
Light and heat in semiconductors: measuring efficiencies efficiently, Western Carolina University (March 31, 1997) and State University of West Georgia (April 7, 1997).
Electrons in quantum dots - why are they so excited when they're all alone? The University of the South (April 15, 1996).
Relaxation of excitons and carriers in strain-induced quantum wires and dots, Sandia National Laboratory (September 18, 1995).
