Research Areas

Thin Film Photovoltaic Materials

Caltech People: Prof. Harry Atwater (APh), Melissa Griggs, Brendan Kayes, Christine Richardson, Katsu Tanabe

Collaborators: Dr. Dan Aiken (Emcore), Dr. David Carlson (BP), Dr. Richard King, Dr. Daniel Law (Spectrolab Inc.), Professor Nathan Lewis (Caltech)


Thin Film Photovoltaics Overview:

Photovoltaics(PV), the direct generation of electric power from sunlight, is a technology which is currently enjoying substantial growth and investment owing to rapid economic growth in developing countries and growing worldwide public sensitivity to the long-term importance of renewable energy sources in industrialized countries as well. While there are many possible options for photovoltaic materials and devices, the key performance metric is the cost per Watt of PV-generated electricity. Thus while photovoltaic solar cells are semiconductor devices, the cost of device processing per unit area must be several orders of magnitude less expensive than typical microelectronics processing. As a result, while most current solar cell manufacturing is done with crystalline or multicrystalline silicon wafers, the future of photovoltaics lies in development of inexpensive thin film devices and processes, and current candidate materials include amorphous silicon (a-Si), copper indium diselenide (CIS) and cadmium telluride (CdTe).


Emerging Research Areas:

1. Crystalline Si Thin Films

Crystalline silicon thin films can exploit the wealth of expertise in silicon processing, but use very thin films. In this approach a crystalline silicon thin (1-30 microns) film is grown on a inexpensive foreign substrate (e.g., glass, ceramic, steel) at low temperatures. Our strategy is to devise crystal growth processes that enable large-grained Si films to be produced at low process temperatures compatible with low-cost substrates, such as glass
.

2. III-V Heterostructures

Currently the world's highest efficiency solar cells are triple junction solar cells made with lattice-matched III-V compound heterostructures. These structures require expensive single crystal substrates and are currently too expensive to be useful for large-scale terrestrial power applications, although they are currently the technology of choice for space power systems that provide onboard power for satellites, unmanned and manned spacecraft. However, these challenges may be overcome by use of wafer bonding and layer transfer techniques to create nonlattice-matched heterostructures on low-cost substrates, so we can enable new design freedoms for tandem solar cells. This approach combined, with monolithic microconcentrator optics, may enable ultrahigh efficiency cells to enter the terrestrial photovoltaics arena.

Available Presentations:

III-V Heterostructures for Ultrahigh Efficiency
Hot Wire CVD for Photovoltaics


Available Publications:

Scanning Laser-Beam-Induced Current Measurements of Lateral Transport Near-Junction Defects in Silicon Heterojunction Solar Cells
Michael G. Deceglie, Hal S. Emmer, Zachary C. Holman, Antoine Descoeudres, Stefaan De Wolf, Christophe Ballif, and Harry A. Atwater
IEEE Journal of Photovoltaics (2014)


Bandgap Tunability in Zn(Sn,Ge)N 2 Semiconductor Alloys
Prineha Narang , Shiyou Chen , Naomi C. Coronel, Sheraz Gul, Junko Yano, Lin-Wang Wang, Nathan S. Lewis, and Harry A. Atwater
Advanced Materials (2013)


Design and Growth of III-V on Si Microwire Array Tandem Solar Cells
Christopher T. Chen, Daniel B. Turner-Evans, Hal Emmer, Shaul Aloni, Harry A. Atwater
IEEE PVSC (2013)


Energy-band Alignment of II-VI/Zn3P2 Heterojunctions from X-ray Photoemission Spectroscopy
Jeffrey P. Bosco, David O. Scanlon, Graeme W. Watson, Nathan S. Lewis, and Harry A. Atwater
Journal of Applied Physics (2013)


Experimental Measurement of Lateral Transport in the Inversion Layer of Silicon Heterojunction Solar Cells
Hal S. Emmer, Michael G. Deceglie, Zachary C. Holman, Antoine Descoeudres, Stefaan De Wolf, Christophe Ballif, and Harry A. Atwater
IEEE PVSC (2013)


Flexible, Transparent Contacts for Inorganic Nanostructures and Thin Films
Daniel B. Turner-Evans , Hal Emmer , Christopher T. Chen , and Harry A. Atwater
Advanced Materials (2013)


Highly efficient GaAs solar cells by limiting light emission angle
Emily D Kosten, Jackson H Atwater, James Parsons, Albert Polman, and Harry A Atwater
Light: Science & Applications (2013)


Nanophotonic Design Principles for Ultrahigh Efficiency Photovoltaics
Harry Atwater, Albert Polman, Emily Kosten, Dennis Callahan, Pierpaolo Spinelli, Carissa Eisler, Matthew Escarra, Emily Warmann, and Cristofer Flowers
AIP Conference Proceedings (2013)


Optical, Electrical, and Solar Energy-conversion Properties of Gallium Arsenide Nanowire-array Photoanodes
Shu Hu, Chun-Yung Chi, Katherine T. Fountaine, Maoqing Yao, Harry A. Atwater, P. Daniel Dapkus, Nathan S. Lewis, and Chongwu Zhou
Energy & Environmental Science (2013)


Optoelectronic Analysis of Multijunction Wire Array Solar Cells
Daniel B. Turner-Evans, Christopher T. Chen, Hal Emmer, William E. McMahon, and Harry A. Atwater
J. Appl Phys (2013)


Phase Stability and Defect Physics of a Ternary ZnSnN 2 Semiconductor: First Principles Insights
Shiyou Chen , Prineha Narang , Harry A. Atwater ,and Lin-Wang Wang
Advanced Materials (2013)


Phototropic Growth Control of Nanoscale Pattern Formation in Photoelectrodeposited Se–Te films
Bryce Sadtler, Stanley P. Burgos, Nicolas A. Batara, Joseph A. Beardslee, Harry A. Atwater, and Nathan S. Lewis,
PNAS (2013)


Rapid Self-assembly of Brush Block Copolymers to Photonic Crystals
Benjamin R. Sveinbjörnsson, Raymond A. Weitekamp, Garret M. Miyake, Yan Xi, Harry A. Atwater, and Robert H. Grubbs
PNAS (2013)


Silicon Solar Cell Light-Trapping Using Defect Mode Photonic Crystals
Kelsey A. Whitesell, Dennis M. Callahan, Harry Atwater
SPIE 8620 (2013)


Solar Cell Efficiency Enhancement via Light Trapping in Printable Resonant Dielectric Nanosphere Arrays
Jonathan Grandidier, Raymond A. Weitekamp, Michael G. Deceglie, Dennis M. Callahan, Corsin Battaglia, Colton R. Bukowsky, Christophe Ballif, Robert H. Grubbs, and Harry A. Atwater
Physica Status Solidi (2013)


Spectrum Splitting Photovoltaics: Polyhedral Specular Reflector Design for Ultra-High Efficiency Modules
Carissa N. Eisler, Emily D. Kosten, Emily C. Warmann, and Harry A. Atwater
39th IEEE Photovoltaic Specialists Conference (2013)


Structural and Optoelectronic Characterization of RF Sputtered ZnSnN 2
Lise Lahourcade , Naomi C. Coronel , Kris T. Delaney , Sujeet K. Shukla , Nicola A. Spaldin , and Harry A. Atwater
Advanced Materials (2013)


Metal–Polymer–Metal Split-Dipole Nanoantennas
Deirdre M. O'Carroll, James S. Fakonas, Dennis M. Callahan, Martin Schierhorn, Harry. A. Atwater
Advanced Materials (2012)


Configuration Optimization of a Nanosphere Array on Top of a Thin Film Solar Cell
Jonathan Grandidier, Dennis Callahan, Harry A. Atwater
IEEE PVSC (2012)


Design of Nanostructured Solar Cells Using Coupled Optical and Electrical Modeling
Mike G. Deceglie, Vivian E. Ferry, A. Paul Alivisatos, and Harry A. Atwater
NanoLetters (2012)


Enhanced Performance of Small GaAs Solar Cells via Edge and Surface Passivation with Trioctylphosphine Sulfide.
Carissa N. Eisler, Matthew T. Sheldon, and Harry A. Atwater
38th IEEE Photovoltaic Specialists Conference (2012)


GaAs Passivation with Trioctylphosphine Sulfide for Enhanced Solar Cell Efficiency and Durability
Matthew T. Sheldon , Carissa N. Eisler , and Harry A. Atwater
Advanced Energy Materials (2012)


Hydrogen-evolution Characteristics of Ni–Mo-coated, Radial Junction, n +p-silicon Microwire Array Photocathodes
Emily L. Warren, James R. McKone, Harry A. Atwater, Harry B. Gray, and Nathan S. Lewis
Energy & Environmental Science (2012)


Passivation of Zn3P2 Substrates by Aqueous Chemical Etching and Air Oxidation
Gregory M. Kimball, Jeffrey P. Bosco, Astrid M. Müller, Syed F. Tajdar, Bruce S. Brunschwig, Harry A Atwater
Journal of Applied Physics (2012)


Photonic Design Principles for Ultrahigh-Efficiency Photovoltaics
Albert Polman, Harry A. Atwater
Nature Materials (2012)


Simulations of solar cell absorption enhancement using resonant modes of a nanosphere array
Jonathan Grandidier, Michael Deceglie, Dennis Callahan, Harry A. Atwater
SPIE 8256 (2012)


Wafer-Scale Growth of Silicon Microwire Arrays for Photovoltaics and Solar Fuel Generation
Adele C. Tamboli, Christopher T. Chen, Emily L. Warren, Daniel B. Turner-Evans, Michael D. Kelzenberg, Nathan S. Lewis, and Harry A. Atwater
IEEE Journal of Photovoltaics (2012)


820 mV Open-Circuit Voltages from Cu2O/CH3CN Junctions
Chengxiang Xiang, Gregory M. Kimball, Ronald L. Grimm, Harry A. Atwater, and Nathan S. Lewis
Energy & Environmental Science (2011)


Compliant Metamaterials for Resonantly Enhanced Infrared Absorption Spectroscopy and Refractive Index Sensing
Imogen M. Pryce, Yousif A. Kelaita, Koray Aydin, Harry A. Atwater
ACS Nano (2011)


Effect of Defect-Rich Epitaxy on Crystalline Silicon/Amorphous Silicon Heterojunction Solar Cells and the Use of Low-Mobility Layers to Improve Performance
Michael Deceglie, Harry A. Atwater
IEEE Photovoltaics Specialists Conference (2011)


First Demonstration of Monolithic InP-Based InAIAs/InGaAsP/InGaAs Triple Junction Solar Cells
Robyn L. Woo1, William D. Hong, Shoghig Mesropian, Marina S. Leite, Harry A. Atwater, Daniel C. Law
PVSC (2011)


Gallium Arsenide Solar Cell Absorption Enhancement Using Whispering Gallery Modes of Dielectric Nanospheres
J. Grandidier, D. Callahan, J. Munday, H. A. Atwater
IEEE (2011)


High-performance Si microwire photovoltaics
Michael D. Kelzenberg, Daniel B. Turner-Evans, Morgan C. Putnam, Shannon W. Boettcher, Ryan M. Briggs, Jae Yeon Baek, Nathan S. Lewis and Harry A. Atwater
Energy & Environmental Science (2011)


InAIAs Epitaxial Growth for Wide Band Gap Solar Cells
Marina Leite, Robyn Woo, William D. Hong, Daniel C. Law, and Harry A. Atwater
(2011)


Light absorption enhancement in thin-film solar cells using whispering gallery modes in dielectric nanospheres
Jonathan Grandidier , Dennis M. Callahan , Jeremy N. Munday , and Harry A. Atwater
Advanced Materials (2011)


Microphotonic parabolic light directors fabricated by two-photon lithography
Jackson H. Atwater, Emily Kosten, Pierpaolo Spinelli, J. Parsons, C. Van Lare
Applied Physics Letters (2011)


Optoelectronic Design of Multijunction Wire-Array Solar Cells
Daniel B. Turner-Evans, Michael D. Kelzenberg, Chris T. Chen, Emily C. Warmann, Adele C. Tamboli, and Harry A. Atwater
IEEE (2011)


Photoelectrochemical Hydrogen Evolution Using Si Microwire Arrays
Shannon W. Boettcher, Emily L. Warren, Morgan C. Putnam, Elizabeth A. Santori, Daniel Turner-Evans, Michael D. Kelzenberg, Michael G. Walter, James R. McKone, Bruce S. Brunschwig, Harry A. Atwater, and Nathan S. Lewis
Journal of the American Chemical Society (2011)


Ray Optical Light Trapping in Silicon Microwires: Exceeding the 2n2 Intensity Limit
Emily D. Kosten, Emily L. Warren, and Harry A. Atwater
Optics Express (2011)


Wafer-Scale Strain Engineering of Ultrathin Semiconductor Crystalline Layers
Marina S. Leite, Emily C. Warmann, Gregory M. Kimball, Stanley P. Burgos, Dennis M. Callahan, and Harry A. Atwater
Advanced Materials (2011)


Wide-band-gap InAlAs solar cell for an alternative multijunction approach
Marina S. Leite, Robyn L. Woo, William D. Hong, Daniel C. Law, and Harry A. Atwater
Applied Physics Letters (2011)


Design Considerations for Plasmonic Photovoltaics
Vivian E. Ferry, Jeremy N. Munday, and Harry A. Atwater
Advanced Materials (2010)


Effects of Bulk and Grain Boundary Recombination on the Efficiency of Columnar-Grained Crystalline Silicon Film Solar Cells
Michael Deceglie, Michael Kelzenberg, Harry Atwater
Proceedings of the 35th IEEE Photovoltaic Specialists Conference (2010)


Energy-Conversion Properties of Vapor-Liquid-Solid–Grown Silicon Wire-Array Photocathodes
Shannon W. Boettcher, Joshua M. Spurgeon, Morgan C. Putnam, Emily L. Warren, Daniel B. Turner-Evans, Michael D. Kelzenberg, James R. Maiolo, Harry A. Atwater, Nathan S. Lewis
Science (2010)


Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications
Michael D. Kelzenberg, Shannon W. Boettcher, Jan A. Petykiewicz, Daniel B. Turner-Evans, Morgan C. Putnam, Emily L. Warren, Joshua M. Spurgeon, Ryan M. Briggs, Nathan S. Lewis & Harry A. Atwater
Nature Materials (2010)


Flexible, Polymer-Supported, Si Wire Array Photoelectrodes
Joshua Spurgeon, Shannon Boettcher, Michael Kelzenberg, Bruce Brunschwig, Harry Atwater, Nathan Lewis
Advanced Materials (2010)


Large Integrated Absorption Enhancement in Plasmonic Solar Cells by Combining Metallic Gratings and Antireflection Coatings
Jeremy N. Munday and Harry A. Atwater
Nano Letters (2010)


Light trapping in ultrathin plasmonic solar cells
Vivian E. Ferry, Marc A. Verschuuren, Hongbo B. T. Li, Ewold Verhagen, Robert J. Walters, Ruud E. I. Schropp, Harry A. Atwater, and Albert Polman
Optics Express (2010)


MG Doping and Alloying in Zn3P2 Heterojunction Solar Cells
Gregory M. Kimball, Nathan S. Lewis, Harry A. Atwater
35th IEEE PVSC (2010)


Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells
Imogen M. Pryce, Daniel D. Koleske, Arthur J. Fischer, and Harry A. Atwater
Applied Physics Letters (2010)


Plasmonics for improved photovoltaic devices
Harry A. Atwater and Albert Polman
Nature Materials (2010)


Si microwire-array solar cells
Morgan Putnam, Shannon Boettcher, Michael Kelzenberg, Daniel Turner-Evans, Joshua Spurgeon, Emily Warren, Ryan Briggs, Nathan Lewis and Harry Atwater
Energy & Environmental Science (2010)


Water-Splitting Photoelectrolysis Reaction Rate via Microscopic Imaging of Evolved Oxygen Bubbles
Andrew J. Leenheer and Harry A. Atwater
Journal of The Electrochemical Society (2010)


10 µm minority-carrier diffusion lengths in Si wires synthesized by Cu-catalyzed vapor-liquid-solid growth
Morgan C. Putnam, Daniel B. Turner-Evans, Michael D. Kelzenberg, Shannon W. Boettcher, Nathan S. Lewis, and Harry A. Atwater
Applied Physics Letters (2009)


How much can guided modes enhance absorption in thin solar cells?
Peter N. Saeta, Vivian E. Ferry, Domenico Pacifici, Jeremy N. Munday, and Harry A. Atwater
Optics Express (2009)


Increased cell efficiency in InGaAs solar cells with dielectric and metal back reflectors
Koray Aydin, Marina S. Leite, and Harry A. Atwater
Proceedings of the 34th IEEE PVSC (2009)


Photoluminescence-based measurements of the energy gap and diffusion length of Zn3P2
Gregory M. Kimball, Astrid M. Müller, Nathan S. Lewis, and Harry A. Atwater
Applied Physics Letters (2009)


Predicted efficiency of Si wire array solar cells
Michael Kelzenberg, Morgan Putnam, Daniel Turner-Evans, Nathan Lewis, Harry Atwater
Proceedings of the 34th IEEE PVSC (2009)


Flexible Polymer-Embedded Si Wire Arrays
Katherine E. Plass, Michael A. Filler, Joshua M. Spurgeon, Brendan M. Kayes, Stephen Maldonado, Bruce S. Brunschwig, Harry A. Atwater, and Nathan S. Lewis
Advanced Materials (2008)


GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates
Melissa J. Archer, Daniel C. Law, Shoghig Mesropian, Moran Haddad, Christopher M. Fetzer, Arthur C. Ackerman, Corinne Ladous, Richard R. King, and Harry A. Atwater
Applied Physics Letters (2008)


Improved electrical properties of wafer-bonded p-GaAs/n-InP interfaces with sulfide passivation
Keisuke Nakayama, Katsuaki Tanabe, and Harry A. Atwater
Journal of Applied Physics (2008)


Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells
Michael D. Kelzenberg, Daniel B. Turner-Evans, Brendan M. Kayes, Michael A. Filler, Morgan C. Putnam, Nathan S. Lewis, and Harry A. Atwater
Nano Letters (2008)


Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells
Vivian E. Ferry, Luke A. Sweatlock, Domenico Pacifici, and Harry A. Atwater
Nano Letters (2008)


Secondary Ion Mass Spectroscopy of Vapor-Liquid-Solid Grown, Au-Catalyzed, Si Wires
Morgan C. Putnam, Michael A. Filler, Brendan M. Kayes, Michael D. Kelzenberg, Yunbin Guan, Nathan S. Lweis, John M. Eller, and Harry A. Atwater
Nano Letters (2008)


Single-Nanowire Si Solar Cells
Michael D. Kelzenberg, Michael A. Filler, Brendan M. Kayes, Morgan C. Putnam, Daniel B. Turner-Evans, Nathan S. Lewis, Harry A. Atwater
Proceedings of the 33rd IEEE PVSC (2008)


High Aspect Ratio Silicon Wire Array Photoelectrochemical Cells
James R. Maiolo III, Brendan M. Kayes, Michael A. Filler, Morgan C. Putnam, Michael D. Kelzenberg, Harry A. Atwater, and Nathan S. Lewis
Journal of the American Chemical Society (2007)


High efficiency InGaAs solar cells on Si by InP layer transfer
James M. Zahler, Katsuaki Tanabe, Corinne Ladous, Tom Pinnington, Frederick D. Newman, and Harry A. Atwater
Applied Physics Letters (2007)


Role of hydrogen in hydrogen-induced layer exfoliation of germanium
James M. Zahler, Anna Fontcuberta i Morral, Melissa J. Griggs, Harry A. Atwater, Yves J. Chabal
Physics Review B (2007)


Design Approaches and Materials Processes for Ultra-high Efficiency Lattice Mismatched Multi-Junction Solar Cells
Melissa J. Griggs, Daniel C. Law, Richard R. King, Arthur C. Ackerman, James M. Zahler, and Harry A. Atwater
Proc. of 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion (2006)


Direct-bonded GaAs/InGaAs tandem solar cell
Katsuaki Tanabe, Daniel J. Aiken, Mark W. Wanlass, Anna Fontcuberta i Morral and Harry A. Atwater
Applied Physics Letters (2006)


Microsecond minority carrier lifetimes in HWCVD-grown films and implications for thin film solar cells
Maribeth S. Mason, Christine E. Richardson, Harry A. Atwater, R. K. Ahrenkiel
Thin Solid Films (2006)


p-n Junction Heterostructure Device Physics Model of a Four Junction Solar Cell
Melissa J. Griggs, Brendan M. Kayes, and Harry A. Atwater
Proc. of SPIE Vol. 6339 (2006)


Synthesis and Characterization of Silicon Nanorod Arrays for Solar Cell Applications
Brendan M. Kayes, Joshua M. Spurgeon, Thomas C. Sadler, Nathan S. Lewis, Harry A. Atwater
IEEE 4th World Conference on Photovoltaic Energy Conversion Proceedings (2006)


A Phase Diagram for Morphology and Properties of Low Temperature Deposited Polycrystalline Silicon Grown by Hot-wire Chemical Vapor Deposition
Christine E. Richardson, Maribeth S. Mason, and Harry A. Atwater
IEEE Proceedings (2005)


A Phase Diagram of Low Temperature Epitaxial Silicon Grown by Hot-wire Chemical Vapor Deposition for Photovoltaic Devices
Christine E. Richardson, Brendan M. Kayes, Matthew J. Dicken, Harry A. Atwater
Proceedings of MRS Spring Meeting (2005)


Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells
Brendan M. Kayes, Nathan S. Lewis, and Harry A. Atwater
Journal of Applied Physics (2005)


Radial pn junction nanorod solar cells: device physics principles and routes to fabrication in silicon
Brendan M. Kayes, Christine E. Richardson, Nathan S. Lewis, Harry A. Atwater
IEEE Proceedings (2005)


Spectroscopic studies of the mechanism for hydrogen-induced exfoliation of InP
Anna Fontcuberta i Morral, James M. Zahler, Melissa J. Griggs, Harry A. Atwater, and Yves J. Chabal
Physical Review B (2005)


Quantitative modelling of nucleation kinetics in experiments for poly-Si growth on SiO2 by hot wire chemical vapor deposition
Maribeth S. Mason, Jason K. Holt, and Harry A. Atwater
Thin Solid Films (2004)


Hot-wire chemical vapor deposition for epitaxial silicon growth on large grained polycrystalline silicon templates
Maribeth S. Mason, Claudine M. Chen, Harry A. Atwater
Thin Solid Films (2003)


Hot-wire chemical vapor deposition of high hydrogen content silicon nitride for solar cell passivation and anti-reflection coating applications
Jason K. Holt, David G. Goodwin, A.M. Gabor, F. Jiang, M. Stavola, Harry A. Atwater
Thin Solid Films (2003)


InGaAs/InP double heterostructures on InP/Si templates fabricated by wafer bonding and hydrogen-induced exfoliation
Anna Fontcuberta i Morral, James M. Zahler, Harry A. Atwater, S. P. Ahrenkiel, and Mark W. Wanlass
Applied Physics Letters (2003)


The aging of tungsten filaments and its effect on wire surface kinetics in hot-wire chemical vapor deposition
Jason K. Holt, Maribeth Swiatek, David G. Goodwin, and Harry A. Atwater
Journal of Applied Physics (2002)


Gas phase and surface kinetic processes in polycrystalline silicon hot-wire chemical vapor deposition
Jason K. Holt, Maribeth Swiatek, David G. Goodwin, R.P. Muller, William A. Goddard III, Harry A. Atwater
Thin Solid Films (2001)


Ion Bombardment Enhanced Grain Growth in Germanium, Silicon, and Gold Thin Films
Harry A. Atwater, Carl V Thompson, Henry I Smith
Journal of Applied Physics (1988)