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  1. AU="Schulte, Kevin L."
  2. AU="Hu, Guanqun"
  3. AU="Li, Jin-Yan"
  4. AU="Stonsaovapak, Siriporn"
  5. AU="Trétarre, Brigitte"

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  1. Article: In Situ Smoothing of Facets on Spalled GaAs(100) Substrates during OMVPE Growth of III-V Epilayers, Solar Cells, and Other Devices: The Impact of Surface Impurities/Dopants.

    McMahon, William E / Braun, Anna K / Perna, Allison N / Coll, Pablo G / Schulte, Kevin L / Boyer, Jacob T / Neumann, Anica N / Geisz, John F / Warren, Emily L / Ptak, Aaron J / Merkle, Arno P / Bertoni, Mariana I / Packard, Corinne E / Steiner, Myles A

    Crystal growth & design

    2024  Volume 24, Issue 8, Page(s) 3218–3227

    Abstract: One possible pathway toward reducing the cost of III-V solar cells is to remove them from their growth substrate by spalling fracture, and then reuse the substrate for the growth of multiple cells. Here we consider the growth of III-V cells on spalled ... ...

    Abstract One possible pathway toward reducing the cost of III-V solar cells is to remove them from their growth substrate by spalling fracture, and then reuse the substrate for the growth of multiple cells. Here we consider the growth of III-V cells on spalled GaAs(100) substrates, which typically have faceted surfaces after spalling. To facilitate the growth of high-quality cells, these faceted surfaces should be smoothed prior to cell growth. In this study, we show that these surfaces can be smoothed during organometallic vapor-phase epitaxy growth, but the choice of epilayer material and modification of the various surfaces by impurities/dopants greatly impacts whether or not the surface becomes smooth, and how rapidly the smoothing occurs. Representative examples are presented along with a discussion of the underlying growth processes. Although this work was motivated by solar cell growth, the methods are generally applicable to the growth of any III-V device on a nonplanar substrate.
    Language English
    Publishing date 2024-04-01
    Publishing country United States
    Document type Journal Article
    ISSN 1528-7483
    ISSN 1528-7483
    DOI 10.1021/acs.cgd.3c01407
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Nucleation and Growth of GaAs on a Carbon Release Layer by Halide Vapor Phase Epitaxy.

    Roberts, Dennice M / Kim, Hyunseok / McClure, Elisabeth L / Lu, Kuangye / Mangum, John S / Braun, Anna K / Ptak, Aaron J / Schulte, Kevin L / Kim, Jeehwan / Simon, John

    ACS omega

    2023  Volume 8, Issue 47, Page(s) 45088–45095

    Abstract: We couple halide vapor phase epitaxy (HVPE) growth of III-V materials with liftoff from an ultrathin carbon release layer to address two significant cost components in III-V device - epitaxial growth and substrate reusability. We investigate nucleation ... ...

    Abstract We couple halide vapor phase epitaxy (HVPE) growth of III-V materials with liftoff from an ultrathin carbon release layer to address two significant cost components in III-V device - epitaxial growth and substrate reusability. We investigate nucleation and growth of GaAs layers by HVPE on a thin amorphous carbon layer that can be mechanically exfoliated, leaving the substrate available for reuse. We study nucleation as a function of carbon layer thickness and growth rate and find island-like nucleation. We then study various GaAs growth conditions, including V/III ratio, growth temperature, and growth rate in an effort to minimize film roughness. High growth rates and thicker films lead to drastically smoother surfaces with reduced threading dislocation density. Finally, we grow an initial photovoltaic device on a carbon release layer that has an efficiency of 7.2%. The findings of this work show that HVPE growth is compatible with a carbon release layer and presents a path toward lowering the cost of photovoltaics with high throughput growth and substrate reuse.
    Language English
    Publishing date 2023-11-15
    Publishing country United States
    Document type Journal Article
    ISSN 2470-1343
    ISSN (online) 2470-1343
    DOI 10.1021/acsomega.3c07162
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Gallium arsenide solar cells grown at rates exceeding 300 µm h

    Metaferia, Wondwosen / Schulte, Kevin L / Simon, John / Johnston, Steve / Ptak, Aaron J

    Nature communications

    2019  Volume 10, Issue 1, Page(s) 3361

    Abstract: We report gallium arsenide (GaAs) growth rates exceeding 300 µm ... ...

    Abstract We report gallium arsenide (GaAs) growth rates exceeding 300 µm h
    Language English
    Publishing date 2019-07-26
    Publishing country England
    Document type Journal Article
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-019-11341-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Publisher Correction: Gallium arsenide solar cells grown at rates exceeding 300 µm h

    Metaferia, Wondwosen / Schulte, Kevin L / Simon, John / Johnston, Steve / Ptak, Aaron J

    Nature communications

    2019  Volume 10, Issue 1, Page(s) 4070

    Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper. ...

    Abstract An amendment to this paper has been published and can be accessed via a link at the top of the paper.
    Language English
    Publishing date 2019-09-03
    Publishing country England
    Document type Published Erratum
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-019-11927-x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Thermophotovoltaic efficiency of 40.

    LaPotin, Alina / Schulte, Kevin L / Steiner, Myles A / Buznitsky, Kyle / Kelsall, Colin C / Friedman, Daniel J / Tervo, Eric J / France, Ryan M / Young, Michelle R / Rohskopf, Andrew / Verma, Shomik / Wang, Evelyn N / Henry, Asegun

    Nature

    2022  Volume 604, Issue 7905, Page(s) 287–291

    Abstract: Thermophotovoltaics (TPVs) convert predominantly infrared wavelength light to electricity via the photovoltaic effect, and can enable approaches to energy ... ...

    Abstract Thermophotovoltaics (TPVs) convert predominantly infrared wavelength light to electricity via the photovoltaic effect, and can enable approaches to energy storage
    MeSH term(s) Electricity ; Hot Temperature ; Infrared Rays ; Temperature
    Language English
    Publishing date 2022-04-13
    Publishing country England
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/s41586-022-04473-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Book ; Online: Sub-0.6 eV Inverted Metamorphic GaInAs Cells Grown on InP and GaAs Substrates for Thermophotovoltaics and Laser Power Conversion

    Schulte, Kevin L. / Friedman, Daniel J. / Dada, Titilope / Guthrey, Harvey L. / da Costa, Edgard Winter / Tervo, Eric J. / France, Ryan M. / Geisz, John F. / Steiner, Myles A.

    2023  

    Abstract: We present inverted metamorphic Ga0.3In0.7As photovoltaic converters with sub-0.60 eV bandgaps grown on InP and GaAs substrates. The compositionally graded buffers in these devices have threading dislocation densities of 1.3x10^6 cm^-2 and 8.9x10^6 cm^-2 ...

    Abstract We present inverted metamorphic Ga0.3In0.7As photovoltaic converters with sub-0.60 eV bandgaps grown on InP and GaAs substrates. The compositionally graded buffers in these devices have threading dislocation densities of 1.3x10^6 cm^-2 and 8.9x10^6 cm^-2 on InP and GaAs, respectively. The devices generate open-circuit voltages of 0.386 V and 0.383 V, respectively, at a current density of ~10 A/cm^2, yielding bandgap-voltage offsets of 0.20 and 0.21 V. We measured their broadband reflectance and used it to estimate thermophotovoltaic efficiency. The InP-based cell is estimated to yield 1.09 W/cm^2 at 1100 degrees C vs. 0.92 W/cm^2 for the GaAs-based cell, with efficiencies of 16.8 vs. 9.2%. The efficiencies of both devices are limited by sub-bandgap absorption, with power weighted sub-bandgap reflectances of 81% and 58%, respectively, which we assess largely occurs in the graded buffers. We estimate that the thermophotovoltaic efficiencies would peak at ~1100 degrees C at 24.0% and 20.7% in structures with the graded buffer removed, if previously demonstrated reflectance is achieved. These devices also have application to laser power conversion in the 2.0-2.3 micron atmospheric window. We estimate peak LPC efficiencies of 36.8% and 32.5% under 2.0 micron irradiances of 1.86 W/cm^2 and 2.81 W/cm^2, respectively.

    Comment: 14 pages, 6 figures
    Keywords Physics - Applied Physics ; Condensed Matter - Materials Science
    Subject code 600
    Publishing date 2023-10-12
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Book ; Online: Surface chemistry models for GaAs epitaxial growth and hydride cracking using reacting flow simulations

    Hassanaly, Malik / Sitaraman, Hariswaran / Schulte, Kevin L. / Ptak, Aaron J. / Simon, John / Udwary, Kevin / Leach, Jacob H. / Splawn, Heather

    2021  

    Abstract: Hydride Vapor Phase Epitaxy (HVPE) is a promising technology that can aid in the cost reduction of III-V materials and devices manufacturing, particularly high-efficiency solar cells for space and terrestrial applications. However, recent demonstrations ... ...

    Abstract Hydride Vapor Phase Epitaxy (HVPE) is a promising technology that can aid in the cost reduction of III-V materials and devices manufacturing, particularly high-efficiency solar cells for space and terrestrial applications. However, recent demonstrations of ultra fast growth rates ($\sim$ 500 $\mu$m/h) via uncracked hydrides are not well described by present models for the growth. Therefore, it is necessary to understand the kinetics of the growth process and its coupling with transport phenomena, so as to enable fast and uniform epitaxial growth. In this work, we derive a kinetic model using experimental data and integrate it into a computational fluid dynamics simulation of an HVPE growth reactor. We also modify an existing hydride cracking model that we validate against numerical simulations and experimental data. We show that the developed growth model and the improved cracking model are able to reproduce experimental growth measurements of \ce{GaAs} in an existing HVPE system.

    Comment: 12 pages, 13 figures, 2 tables
    Keywords Physics - Applied Physics ; Physics - Computational Physics ; Physics - Fluid Dynamics
    Subject code 612
    Publishing date 2021-09-22
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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