TIMOTHY H. GFROERER

            Department of Physics, Box 7133

            Davidson College, 209 Ridge Road

            Davidson, NC 28035

            phone: (704) 894-2319, email: tigfroerer (at) davidson (dot) edu

            website: http://www.phy.davidson.edu/FacHome/thg/Welcome.htm

 

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, (2004-11) Associate, (2011-Present) Professor of Physics

•     Taught Advanced Laboratory (junior/senior-level experimental physics),

      converted instrument/computer interfacing to the LabVIEW environment and

      initiated a wide variety of new experiments on nonlinear/coupled mechanical oscillators, 

      statistical mechanics with macroscopic toys, thermal distributions in semiconductor devices,

      thermal diffusivity imaging, saturated absorption, quantum entanglement, ultrafast optics, and

      free-space, fiber-based, and single photon interferometry

•     Taught junior-level Electronics and Instrumentation emphasizing semiconductor device physics,

      and including an in-depth investigation of practical photovolatic systems

•     Taught Modern Physics, introduced new experiments on semiconductor quantum wells and

      ultrafast optics and implemented a major revision of the blackbody radiation experiment to include

      spectral analysis with FTIR spectroscopy

•     Developed and team-taught a new interdisciplinary course on 

      Philosophical Issues in Modern Physics with Philosophy Professor David Robb

•     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 defects in semiconductors with

                                           application to optoelectronic devices.  Experimental techniques

                                           include excitation, temperature, position, and time-dependent

                                           measurements of photoluminescence, heat, and capacitance.

 

Research Experience

            Charlotte Research Institute (2011-2012)  Distinguished Visiting Professor

            Host: Bissell Distinguished Professor Yong Zhang

            National Renewable Energy Laboratory (2004-2005)  Visiting Senior Scientist

            Host: Research Fellow Richard K. Arhenkiel

            Davidson College (1999-Present)  Assistant/Associate/Full 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), Caroline Vaughan ('10),

Dan Hampton ('11), KyungTaek Lim ('11), Mark Crowley ('11), Ryan Crum ('11), Ashley Finger ('14),

Keyuan Zhou ('15), Grace Watt ('15), Ben Stroup ('16), Collin Epstein ('18), and Christina Chen ('19).

            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

            2011-2012      Duke Energy Distinguished Visiting Faculty Award, Charlotte Research Institute,

            (sabbatical)     $30,000.

            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

•        Advisor and Liaison Officer, Engineering Dual Degree Program (2010 - Present)

•        Member, Davidson College Admissions Committee (2012 - 2015)

•        Coordinator, Davidson College Physics Department Seminar Series, (2001 - 2010)

•        Member, Associate Deans Search Advisory Committee (2010)

•        External Reviewer, Berry College Physics Department (2009)

•        Reviewer, Council on Undergraduate Research Posters on the Hill (2009 and 2010)

•        Member, Davidson College Ethnic Diversity Committee (2005-2011) and

         Diversity of Faculty and Staff Strategic Plan Implementation Team (2009 - 2010)

•        Nutty Professor, Davidson Elementary School (2008 - 2010)

•        Member, Local Organizing Committee for the Spring 2008 NC-AAPT Meeting

         and Host, 2008 Visit by Physicist David Mermin to Davidson College

•        Member, 2005 (Inaugural) and 2007 International Sturge Prize Committees

•        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 (2000 - Present)

•        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

 


Publications (with student collaborators in red)

Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging, S. Zhang, L.Q. Su, J. Kon, T. Gfroerer, M.W. Wanlass, and Yong Zhang, Journal of Luminescence 185, 200 (2017). Download pdf file.

Combining photoluminescence and photocurrent measurements to distinguish photovoltaic losses, T.H. Gfroerer, Ben Stroup (Davidson '16), Collin Epstein (Davidson '18), Yong Zhang and Zhiqiang Liu, Proceedings of the 43rd Photovoltaic Specialists Conference (IEEE, 2016) pp. 1549-1552. Download pdf file.

Thermal diffusivity imaging, Tim Gfroerer, Ryan Phillips (Davidson '16), and Peter Rossi (Davidson '15), FEATURE ARTICLE in the American Journal of Physics 83, 923 (2015). Download pdf file.2

Spatial resolution versus data acquisition efficiency in mapping an inhomogeneous system with species diffusion, Fengxiang Chen, Yong Zhang, T.H. Gfroerer, A.N. Finger (Davidson '14), and M.W. Wanlass, Scientific Reports 5, 10542 (2015). 

Circuits in the sun: solar panel physics, Tim Gfroerer, FEATURE ARTICLE in The Physics Teacher 51, 403 (2013). THE BEST OF THE PHYSICS TEACHER, 2013-2014. Download pdf file.2

Modeling photoluminescence spatial mapping of an isolated defect under uniform and selective excitation, Fengxiang Chen, Yong Zhang, T.H. Gfroerer, A.N. Finger (Davidson '14), and M.W. Wanlass, Proceedings of the 39th Photovoltaic Specialists Conference (IEEE, 2013) pp. 1402-1405. 

An extended defect as a sensor for free carrier diffusion in a semiconductor, T.H. Gfroerer, Yong Zhang, and M.W. Wanlass, Applied Physics Letters 102, 012114 (2013). Download pdf file.1

A comparison of photoluminescence imaging and confocal photoluminescence microscopy in the study of diffusion near isolated extended defects in GaAs, T.H. Gfroerer, Yong Zhang, and M.W. Wanlass, Proceedings of the 38th Photovoltaic Specialists Conference (IEEE, 2012) pp. 1624-1626.  Download pdf file.

Excitation-dependent recombination and diffusion near an isolated dislocation in GaAs, T.H. Gfroerer, C.M. Crowley (Davidson '11), C.M. Read (Davidson '10), and M.W. Wanlass, Journal of Applied Physics 111, 093712 (2012).  Download pdf file.1 

Defect states with an occupation-dependent lattice configuration in Zinc-doped Ga(0.58)In(0.42)P on GaAs, T.H. Gfroerer, D.G. Hampton (Davidson '11), and M.W. Wanlass, Proceedings of the 35th Photovoltaic Specialists Conference (IEEE, 2010) pp. 2026-2028.  Download pdf file.

AX-type defects in zinc-doped GaAs(1-x)P(x) on GaAs, T.H. Gfroerer, D.G. Hampton (Davidson '11), P.R. Simov (Davidson '08), and M.W. Wanlass, Journal of Applied Physics 107, 123719 (2010).  Download pdf file.1

Defect-related trapping and recombination in metamorphic GaAs(0.72)P(0.28) grown on GaAs, T.H. Gfroerer, P.R. Simov (Davidson '08), B.A. West (Davidson '08), and M.W. Wanlass, Proceedings of the 33rd Photovoltaic Specialists Conference (IEEE, 2008) pp. 1-4.  Download pdf file.

Squiggle Ball capture: a simple, visual kinetic theory experiment, Tim Gfroerer and Ken Rathbun, The Physics Teacher 45, 344 (2007).  Download pdf file.2

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.1

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.1

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.1

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.1

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). Download pdf file.1

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 (1997).

 

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, S.R. Das, and L. Lebrun, Physical Review B 53, 16474 (1996).

 

Magneto-spectroscopy of GaAs/AlGaAs strain-induced quantum wires and dots, Timothy H. Gfroerer, Ph.D. Thesis, Dartmouth College (1996).

 

The diamagnetic shift of excitons in 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, in High Magnetic Fields in the Physics of Semiconductors, edited by D. Heiman (World Scientific, Singapore, 1995), pp. 488-491.

 

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).

 

1 Copyright American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

2 Copyright American Association of Physics Teachers. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Association of Physics Teachers.

Meeting Contributions (with student collaborators in red)

Imaging Laser-Excited Blue LEDs, Ruiming Chen ('19), Collin Epstein ('18), Tim Gfroerer, and Yong Zhang, Southeastern Section of the American Physical Society Meeting (2017). Download Poster.

Organization by topic enhances communication in advanced lab, Tim Gfroerer, American Association of Physics Teachers Winter Meeting in Atlanta, GA (2017).  Download Presentation.

Combining photoluminescence and photocurrent measurements to distinguish photovoltaic losses, T.H. Gfroerer, Ben Stroup ('16), Collin Epstein ('18), Yong Zhang and Zhiqiang Liu, Photovoltaic Specialists Conference in Portland, OR (2016). Download Poster.

Photoluminescence and photocurrent in a blue LED, Ben Stroup ('16), Tim Gfroerer, and Yong Zhang, North Carolina Section of the American Association of Physics Teachers Meeting (2015).  Download Poster.

Modeling radial thermal diffusion, Ryan Phillips ('16), Peter Rossi ('15), and Tim Gfroerer, North Carolina Section of the American Association of Physics Teachers Meeting (2015).  Download Poster.

Understanding LED function and mechanisms of energy loss, Grace Watt ('15), Tim Gfroerer, and Yong Zhang, APS Conference for Undergraduate Women in Physics at the Research Triangle (2015).  Download Poster.

Recombination modeling for GaAs Solar Cells, Keyuan Zhou ('15), Tim Gfroerer, and Yong Zhang, Southeastern Section of the American Physical Society Meeting (2014).  Download Poster.

Using a semiconductor defect to connect diffusion lengths with lifetimes, Ashley Finger ('14) and Tim Gfroerer, SPS Outstanding Presentation Award at the American Association of Physics Teachers Winter Meeting in Orlando, FL (2014). Download Presentation.

Modeling photoluminescence spatial mapping of an isolated defect under uniform and selective excitation, Fengxiang Chen, Yong Zhang, T.H. Gfroerer, A.N. Finger ('14), and M.W. Wanlass, Photovoltaic Specialists Conference in Tampa, FL (2013). 

Photovoltaics at Davidson College - a community-based learning project, Tim Gfroerer, American Association of Physics Teachers Winter Meeting in New Orleans, LA (2013).  Download Poster.

A comparison of photoluminescence imaging and confocal photoluminescence microscopy in the study of diffusion near isolated extended defects in GaAs, Tim Gfroerer, Yong Zhang, and Mark Wanlass, Photovoltaic Specialists Conference in Austin, TX (2012).  Download Presentation.

Mapping free carrier diffusion in GaAs with radiative- and heat-generating recombination, Tim Gfroerer, Ryan Crum ('11), and Mark Wanlass, American Physical Society March Meeting in Dallas, TX (2011).  Download Presentation.

Exploring free carrier diffusion with light- and heat-generating recombination, Ryan Crum ('11), Tim Gfroerer, and Mark Wanlass, American Association of Physics Teachers Winter Meeting in Jacksonville, FL (2011).  Download Presentation.

Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs, Mark Crowley ('11), Tim Gfroerer, and Mark Wanlass, American Association of Physics Teachers Winter Meeting in Jacksonville, FL (2011).  Download Presentation.

Study of radiative and heat-generating recombination in GaAs, Ryan Crum ('11), Tim Gfroerer, and Mark Wanlass, North Carolina Section of the American Association of Physics Teachers Fall Meeting (2010).  Download Poster.

Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs, Mark Crowley ('11), Tim Gfroerer, and Mark Wanlass, North Carolina Section of the American Association of Physics Teachers Fall Meeting (2010).  Download Poster.

Defect states with an occupation-dependent lattice configuration in Zinc-doped Ga(0.58)In(0.42)P on GaAs, Tim Gfroerer, Dan Hampton ('11), and Mark Wanlass, Photovoltaic Specialists Conference in Honolulu, HI (2010).  Download Poster.

Photocapacitance measurements on GaP alloys for high efficiency solar cells, Dan Hampton ('11), Tim Gfroerer, and Mark Wanlass, SPS Outstanding Presentation Award at the American Physical Society March Meeting in Portland, OR (2010).  Download Presentation.

How does diffusion affect radiative efficiency measurements? Caroline Vaughan ('10), Tim Gfroerer, and Mark Wanlass, SPS Outstanding Presentation Award at the American Physical Society March Meeting in Portland, OR (2010).  Download Poster.

Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs, Mac Read ('10), Tim Gfroerer, and Mark Wanlass, SPS Outstanding Presentation Award at the American Physical Society March Meeting in Portland, OR (2010).  Download Poster.

Photocapacitance measurements on GaP alloys for high efficiency solar cells, Dan Hampton ('11), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2009).  Download Poster.

How does diffusion affect radiative efficiency measurements? Caroline Vaughan ('10), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2009).  Download Poster.

Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs, Mac Read ('10), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2009).  Download Poster.

Imaging and modeling diffusion to isolated defects in a GaAs/GaInP heterostructure, Tim Gfroerer, Mac Read ('10), Caroline Vaughan ('10), and Mark Wanlass, International Conference on Defects - Recognition, Imaging, and Physics in Semiconductors, Wheeling, WV (2009).  Download Poster.

Building cooperation and community in transitional (introductory to upper-level) physics classes, Tim Gfroerer, American Association of Physics Teachers Winter Meeting in Chicago, IL (2009).   Download Presentation.

Stretched exponential transport transients in GaP alloys for high efficiency solar cells, Dan Hampton ('11), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2008).  Download Poster.

Exploring defect level position and occupation in GaAsP via recombination analysis, KyungTaek Lim ('11), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2008).  Download Poster.

Imaging and modeling diffusion to defects in GaAs, Mac Read ('10), Tim Gfroerer, and Mark Wanlass, Southeastern Section of the American Physical Society Meeting (2008).  Download Poster.

Defect-related trapping and recombination in metamorphic GaAs(0.72)P(0.28) 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, Tim Gfroerer and Mark 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.

Observation of an anomalous minority carrier trap in n-type InGaAs, Tim Gfroerer, Kiril Simov ('05), and Mark Wanlass, International Conference on Indium Phosphide and Related Materials in Glasgow, SCOTLAND (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, Patten Priestley (Davidson '03), Tim Gfroerer, Malu Fairley (Spelman '03), and Mark 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, Emmett Weindruch (Davidson '01), Tim Gfroerer, and Mark 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, Tim Nagle (James Madison '01) and Tim Gfroerer, Best Student Paper Award at the Annual Meeting of the Virginia Academy of Science (1999).

Beam control in light emitting diodes with integral reflectors, Tim Gfroerer, Eric Cornell, and Mark Wanlass, American Physical Society Centennial Meeting in Atlanta, GA (1999).

Increasing the external radiative efficiency of InGaAs/InP heterostructures, Tim Gfroerer, Eric Cornell, and Mark Wanlass, American Physical Society March Meeting in Los Angeles, CA (1998).

Hot luminescence from GaAs/AlGaAs 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, S.R. Das, and L. Lebrun, American Physical Society March Meeting in St. Louis, MO (1996).

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 Meeting in San Jose, CA (1995).

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

Defects in solar cell materials: the good, the bad, and the ugly, Wake Forest University Physics Colloquium (January 25, 2012) and Davidson College Physics Seminar (September 20, 2012).

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).