Mapping free carrier diffusion in GaAs with radiative and heat- generating recombination Tim Gfroerer and Ryan Crum Davidson College, Davidson, NC with.

Slides:

Advertisements

Similar presentations

Semiconductor Device Physics

Advertisements

Photoreflectance of Semiconductors Tyler A. Niebuhr.

Study of Radiative and Heat-Generating Recombination in GaAs Ryan Crum and Tim Gfroerer, Davidson College, Davidson, NC Mark Wanlass, National Renewable.

Defects in solar cell materials: the good, the bad, and the ugly Tim Gfroerer Davidson College, Davidson, NC with Yong Zhang University of Charlotte.

Charge carriers must move to accommodate the bias-dependent depletion layer edge in a diode. Meanwhile, the capacitance depends on the position of the.

Photovoltaic Materials and Technology Philip Griffin 3/02/10 University of Tennessee- Knoxville Department of Physics 14 MW, 70,000.

Conclusions and Acknowledgements Theoretical Fits Novel Materials for Heat-Based Solar Cells We are studying a set of materials that may be useful for.

Radiative efficiency of light-emitting materials Tim Gfroerer Davidson College, Davidson, NC - Funded by Research Corporation and the Petroleum Research.

100 µm Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs Mac Read and Tim Gfroerer, Davidson College, Davidson, NC.

Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter III June 1, 2015June 1, 2015June 1, 2015 Carrier Transport Phenomena.

A-Si:H application to Solar Cells Jonathon Mitchell Semiconductors and Solar Cells.

Studies of Minority Carrier Recombination Mechanisms in Beryllium Doped GaAs for Optimal High Speed LED Performance An Phuoc Doan Department of Electrical.

Chapter 15 Molecular Luminescence Spectrometry Molecular Fluorescence  Optical emission from molecules that have been excited to higher energy levels.

EE580 – Solar Cells Todd J. Kaiser Lecture 05 P-N Junction 1Montana State University: Solar Cells Lecture 5: P-N Junction.

Solar Cells Outline. Single-Junction Solar Cells. Multi-Junction Solar Cells.

Design, Development, and Testing of a Transient Capacitance Spectroscopy System Presented by: Kiril Simov Special thanks to: Dr. Tim Gfroerer Department.

Temperature-Dependent Transient Capacitance in InGaAs/InP-based Diodes Kiril Simov and Tim Gfroerer Davidson College Mark Wanlass NREL Supported by the.

Stretched exponential transport transients in GaP alloys for high efficiency solar cells Dan Hampton and Tim Gfroerer, Davidson College, Davidson, NC Mark.

Solar Cells Early development of solar tech. starts in the 1960s Conversion of sunlight to electricity – by photovoltaic effect In 1974 only.

Fig 2a: Illustration of macroscopic defects Diffusion lengths are calculated by the equation where μ is the mobility of electron with literature value.

Solar Cells, Sluggish Capacitance, and a Puzzling Observation Tim Gfroerer Davidson College, Davidson, NC with Mark Wanlass National Renewable Energy Lab,

When defects are present in a semiconductor, intermediate energy levels are formed allowing carriers to “step” down to lower energy levels and recombine.

Tzveta Apostolova Institute for Nuclear Research and Nuclear Energy,

Charge Carrier Related Nonlinearities

TIM GFROERER, Davidson College Davidson, NC USA

Modeling defect level occupation for recombination statistics Adam Topaz and Tim Gfroerer Davidson College Mark Wanlass National Renewable Energy Lab Supported.

Basic Electronics By Asst Professor : Dhruba Shankar Ray For B.Sc. Electronics Ist Year 1.

Journal Club 13 July 2011 Tuğrul Çağrı CİNKARA. MIT, mechanical engineering.

NEEP 541 Ionization in Semiconductors - II Fall 2002 Jake Blanchard.

Time-Resolved Photoluminescence Spectroscopy of InGaAs/InP Heterostructures* Colleen Gillespie and Tim Gfroerer, Davidson College, Davidson, NC Mark Wanlass,

While lattice-matched Ga 0.51 In 0.49 P on GaAs has the ideal bandgap for the top converter in triple- junction GaAs-based solar cells, more complex designs.

SAINT-PETERSBURG STATE UNIVERSITY EXPERIMENTAL STUDY OF SPIN MEMORY IN NANOSTRUCTURES ROMAN V. CHERBUNIN.

Photocapacitance measurements on GaP alloys for high efficiency solar cells Dan Hampton and Tim Gfroerer, Davidson College, Davidson, NC Mark Wanlass,

Ch 140 Lecture Notes #13 Prepared by David Gleason

LIFETIMES AND DIFFUSION LENGTHS A STUDY IN SEMICONDUCTOR PHYSICS Ashley Finger and Dr. Tim Gfroerer Davidson College.

How does diffusion affect radiative efficiency measurements? Caroline Vaughan and Tim Gfroerer, Davidson College, Davidson, NC Mark Wanlass, National Renewable.

Using the model and algorithm shown to the right, we obtain the theoretical images above. These images, with A=4.2*10 7 cm 3 /s (defect pixel) and A=8.2*10.

Carrier Transport Phenomena And Measurement Chapter 5 26 February 2014

ECEE 302: Electronic Devices

Looking Inside Hidden Excitons with THz Radiation Tim Gfroerer Davidson College Supported by the American Chemical Society – Petroleum Research Fund.

Luminescence basics Types of luminescence

Introduction to semiconductor technology. Outline –4 Excitation of semiconductors Optical absorption and excitation Luminescence Recombination Diffusion.

Photoluminescence and Photocurrent in a Blue LED Ben Stroup & Timothy Gfroerer, Davidson College, Davidson, NC Yong Zhang, University of North Carolina.

Modeling Radial Thermal Diffusion Ryan Phillips, Tim Gfroerer, and Peter Rossi Physics Department, Davidson College, Davidson, NC Abstract Thermal conduction.

Chapter 4 Excess Carriers in Semiconductors

Notes 27 February 2013.

Imaging and modeling diffusion to isolated defects in a GaAs/GaInP heterostructure Tim Gfroerer, Mac Read, and Caroline Vaughan, Davidson College, Davidson,

Defect-related trapping and recombination in metamorphic GaAs 0.72 P 0.28 grown on GaAs Tim Gfroerer, Peter Simov, and Brant West, Davidson College, Davidson,

How does diffusion affect radiative efficiency measurements? Caroline Vaughan and Tim Gfroerer, Davidson College, Davidson, NC Mark Wanlass, National Renewable.

Carrier generation and recombination A sudden increase in temperature increases the generation rate. An incident burst of photons increases the generation.

Thermally activated radiative efficiency enhancement in a GaAs/GaInP heterostructure* Brant West and Tim Gfroerer, Davidson College Mark Wanlass, National.

Animation Demonstration No. 2. Interaction of Light with Semiconductors Normally a semiconductor material has only a few thermally excited free electrons.

Issued: May 5, 2010 Due: May 12, 2010 (at the start of class) Suggested reading: Kasap, Chapter 5, Sections Problems: Stanford University MatSci.

Outline Review Material Properties Band gap Absorption Coefficient Mobility.

SOLAR PANELS Photovoltaic cell Photovoltaic

Chapter 4 Excess Carriers in Semiconductors

Review of semiconductor physics

Imaging and modeling diffusion to defects in GaAs Tim Gfroerer,Davidson College, Davidson, NC with Mark Wanlass, National Renewable Energy Lab, CO Diffusion.

Defect-related recombination near an isolated defect in GaAs Tim Gfroerer,Davidson College, Davidson, NC with Mark Wanlass, National Renewable Energy.

SOLAR PANELS Photovoltaic cell Photovoltaic

Carrier Transport Phenomena And Measurement Chapters 5 and 6 22 and 25 February 2019.

Carrier Transport Phenomena And Measurement Chapters 5 and 6 13 and 15 February 2017.

Reciprocal capacitance transients

Dan Hampton and Tim Gfroerer , Davidson College, Davidson, NC

Recombination in low-bandgap InGaAs Tim Gfroerer Davidson College, Davidson, NC with Mark Wanlass National Renewable Energy Lab, CO ~ Supported by.

Multi-Exciton Generation and Solar Cell Physics

Observation of an anomalous minority carrier trap in n-type InGaAs Tim Gfroerer and Kiril Simov Davidson College, USA Mark Wanlass National Renewable.

J. Peter Campbell and Tim Gfroerer Davidson College, Davidson, NC

Mac Read and Tim Gfroerer, Davidson College, Davidson, NC

Presentation transcript:

Mapping free carrier diffusion in GaAs with radiative and heat- generating recombination Tim Gfroerer and Ryan Crum Davidson College, Davidson, NC with Mark Wanlass National Renewable Energy Lab, Golden, CO ~ Supported by the American Chemical Society – Petroleum Research Fund ~

Solar Cell Operation Conduction Band Valence Band PHOTON ENERGY ELECTRON E-Field E- HOLE E-Field E CURRENT ABSORPTION When a photon is absorbed, an electron is excited into the conduction band, leaving a hole behind in the valence band. Some heat is lost, reducing efficiency. Then an internal electric field sweeps the electrons and holes away, creating electricity. HEAT

Light- and Heat-Generating Recombination Electrons can recombine with holes by releasing light or heat. This loss mechanism also reduces the efficiency of a solar cell. Conduction Band Valence Band Defect Level - + HEAT Conduction Band Valence Band ENERGY Photon - + Rate ≈ A x n (n = carrier density)Rate ≈ B x n 2 (n = carrier density)

Experimental Setup Laser spot ~ 4  m diameter GaAs sample (plan view) Thermal Camera Luminescence Camera

Time evolution of thermal profile Laser on! Heat loss Thermal diffusion

Luminescence and Thermal Profiles

Square-root of the Luminescence Rate ≈ B x n 2 Rate ≈ A x n

Free-Carrier or Thermal Diffusion?!

Conclusions We use optical and thermal imaging to map the free-carrier density near a localized photo-excitation source. The density profiles agree when we account for the bimolecular nature of radiative recombination. BUT: a thermal diffusion calculation also mimics the temperature profile … So what have we measured?! We’ll figure it out!