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Supple E, Gaspe C, Richardson CJK, Gorman BP. Towards Atomic Scale Tomography Using Correlative 4-D STEM, Strain Mapping, and Atom Probe Tomography. Microsc Microanal 2023; 29:603-604. [PMID: 37613392 DOI: 10.1093/micmic/ozad067.292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Edwin Supple
- Colorado School of Mines, Metallurgical and Materials Engineering, Golden, CO, USA
| | - Chomani Gaspe
- Laboratory for Physical Sciences, College Park, MD, USA
| | | | - Brian P Gorman
- Colorado School of Mines, Metallurgical and Materials Engineering, Golden, CO, USA
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2
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Kelly TF, Gorman BP, Ringer SP. Introduction to Atomic-Scale Tomography. Microsc Microanal 2023; 29:589-590. [PMID: 37613014 DOI: 10.1093/micmic/ozad067.284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
| | - Brian P Gorman
- Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO, United States
| | - Simon P Ringer
- School of Aerospace, Mechanical & Mechatronic Engineering, University of Sydney, Sydney, Australia
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3
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Gorman BP, Kelly TF. Comparing Methodologies for Achieving Atomic-Scale Tomography. Microsc Microanal 2023; 29:596-597. [PMID: 37613188 DOI: 10.1093/micmic/ozad067.288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, United States
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4
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Ceguerra AV, Breen AJ, Cairney JM, Ringer SP, Gorman BP. Integrative Atom Probe Tomography Using Scanning Transmission Electron Microscopy-Centric Atom Placement as a Step Toward Atomic-Scale Tomography. Microsc Microanal 2021; 27:140-148. [PMID: 33468273 DOI: 10.1017/s1431927620024873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Current reconstruction methodologies for atom probe tomography (APT) contain serious geometric artifacts that are difficult to address due to their reliance on empirical factors to generate a reconstructed volume. To overcome this limitation, a reconstruction technique is demonstrated where the analyzed volume is instead defined by the specimen geometry and crystal structure as determined by transmission electron microscopy (TEM) and diffraction acquired before and after APT analysis. APT data are reconstructed using a bottom-up approach, where the post-APT TEM image is used to define the substrate upon which APT detection events are placed. Transmission electron diffraction enables the quantification of the relationship between atomic positions and the evaporated specimen volume. Using an example dataset of ZnMgO:Ga grown epitaxially on c-plane sapphire, a volume is reconstructed that has the correct geometry and atomic spacings in 3D. APT data are thus reconstructed in 3D without using empirical parameters for the reverse projection reconstruction algorithm.
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Affiliation(s)
- Anna V Ceguerra
- Australian Centre for Microscopy & Microanalysis (ACMM), The University of Sydney, Sydney, NSW2006, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering (AMME), The University of Sydney, Sydney, NSW2006, Australia
| | - Andrew J Breen
- Australian Centre for Microscopy & Microanalysis (ACMM), The University of Sydney, Sydney, NSW2006, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering (AMME), The University of Sydney, Sydney, NSW2006, Australia
| | - Julie M Cairney
- Australian Centre for Microscopy & Microanalysis (ACMM), The University of Sydney, Sydney, NSW2006, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering (AMME), The University of Sydney, Sydney, NSW2006, Australia
| | - Simon P Ringer
- Australian Centre for Microscopy & Microanalysis (ACMM), The University of Sydney, Sydney, NSW2006, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering (AMME), The University of Sydney, Sydney, NSW2006, Australia
| | - Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO80401, USA
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5
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Abstract
Nanoscale superlattices represent a compelling platform for designed materials as the specific identity and spatial arrangement of constituent layers can lead to tunable properties. A number of kinetically stabilized, nonepitaxial superlattices with almost limitless structural tunability have been reported in telluride and selenide chemistries but have not yet been extended to sulfides. Here, we present SnS-TaS2 nanoscale superlattices with tunable layer architecture. Layered amorphous precursors are prepared as thin films programmed to mimic the targeted superlattice; subsequent low temperature annealing activates self-assembly into crystalline nanocomposites. We investigate structure and composition of superlattices comprised of monolayers of TaS2 and 3-7 monolayers of SnS per repeating unit. Furthermore, a graded precursor preparation approach is introduced, allowing stabilization of superlattices with multiple stacking sequences in a single preparation. Controlled synthesis of the architecture of nanoscale superlattices is a critical path toward tuning their exotic properties and enabling integration with electronic, optical, or quantum devices.
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Affiliation(s)
- Dennice M Roberts
- Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Dylan Bardgett
- Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
- Microelectronics Technology Department, The Aerospace Corporation, El Segundo, California 90245, United States
| | - John D Perkins
- Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Andriy Zakutayev
- Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Sage R Bauers
- Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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6
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Affiliation(s)
- Youjiao Yu
- Department of Statistical ScienceBaylor University Waco, Texas USA
| | - Brian P. Gorman
- Department of Metallurgical and Materials EngineeringColorado School of Mines, Golden Colorado USA
| | - Amanda S. Hering
- Department of Statistical ScienceBaylor University Waco, Texas USA
- One Bear Place #97140; Waco Texas USA
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7
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Chiaramonti AN, Miaja-Avila L, Caplins BW, Blanchard PT, Diercks DR, Gorman BP, Sanford NA. Field Ion Emission in an Atom Probe Microscope Triggered by Femtosecond-Pulsed Coherent Extreme Ultraviolet Light. Microsc Microanal 2020; 26:258-266. [PMID: 32160938 PMCID: PMC7195254 DOI: 10.1017/s1431927620000203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This paper describes initial experimental results from an extreme ultraviolet (EUV) radiation-pulsed atom probe microscope. Femtosecond-pulsed coherent EUV radiation of 29.6 nm wavelength (41.85 eV photon energy), obtained through high harmonic generation in an Ar-filled hollow capillary waveguide, successfully triggered controlled field ion emission from the apex of amorphous SiO2 specimens. The calculated composition is stoichiometric within the error of the measurement and effectively invariant of the specimen base temperature in the range of 25 K to 150 K. Photon energies available in the EUV band are significantly higher than those currently used in the state-of-the-art near-ultraviolet laser-pulsed atom probe, which enables the possibility of additional ionization and desorption pathways. Pulsed coherent EUV light is a new and potential alternative to near-ultraviolet radiation for atom probe tomography.
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Affiliation(s)
- Ann N. Chiaramonti
- Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Luis Miaja-Avila
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Benjamin W. Caplins
- Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Paul T. Blanchard
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - David R. Diercks
- Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO 80401, USA
| | - Brian P. Gorman
- Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO 80401, USA
| | - Norman A. Sanford
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
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8
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Burton GL, Wright S, Stokes A, Diercks DR, Clarke A, Gorman BP. Orientation mapping with Kikuchi patterns generated from a focused STEM probe and indexing with commercially available EDAX software. Ultramicroscopy 2019; 209:112882. [PMID: 31765818 DOI: 10.1016/j.ultramic.2019.112882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 10/24/2019] [Accepted: 11/01/2019] [Indexed: 10/25/2022]
Abstract
Relating a crystal's microscopic structure-such as orientation and size-to a material's macroscopic properties is of great importance in materials science. Although most crystal orientation microscopy is performed in the scanning electron microscope (SEM), transmission electron microscopy (TEM)-based methods have a number of benefits, including higher spatial resolution. Current TEM orientation methods have either specific hardware requirements or use software that has limited scope, utility, or availability. In this article, a technique is described for orientation mapping using Kikuchi diffraction patterns generated from a focused STEM probe. One key advantage is that indexing and analysis of the patterns and maps occurs in the robust OIM Analysis software, currently widely used for electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) analysis. It was found that with minimal to no image processing and by changing only a few software parameters, reliable indexing of Kikuchi patterns is possible. Three samples, a deformed β-Titanium (Ti), a medium carbon heat-treated steel, and BaCe0.8Y0.2O3-δ were tested to determine the effectiveness of the approach. In all three measurements the algorithms effectively and reliably determined the phases and the crystal orientations of the features measured. For the two orientation maps produced, less than 5% of the patterns were misindexed including boundary areas where overlapping patterns existed. An angular resolution of 0.15° was achieved while features <25 nm were able to be spatially resolved.
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Affiliation(s)
- George L Burton
- Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA.
| | - Stuart Wright
- EDAX, 392 East 12300 South, Suite H, Draper, UT 84020, USA
| | - Adam Stokes
- Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA
| | - David R Diercks
- Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA
| | - Amy Clarke
- Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA
| | - Brian P Gorman
- Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA
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Chiaramonti AN, Miaja-Avila L, Blanchard PT, Diercks DR, Gorman BP, Sanford NA. Atom Probe Tomography Using a Wavelength-Tunable Femtosecond-Pulsed Coherent Extreme Ultraviolet Light Source. Microsc Microanal 2019; 25:314-315. [PMID: 35979403 PMCID: PMC9380740 DOI: 10.1017/s1431927619002307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
| | - Luis Miaja-Avila
- National Institute of Standards and Technology, Boulder, CO, USA
| | | | - David R. Diercks
- Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, USA
| | - Brian P. Gorman
- Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, USA
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10
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Chiaramonti AN, Miaja-Avila L, Blanchard PT, Diercks DR, Gorman BP, Sanford NA. A Three-Dimensional Atom Probe Microscope Incorporating a Wavelength-Tuneable Femtosecond-Pulsed Coherent Extreme Ultraviolet Light Source. MRS Adv 2019; 4:10.1557/adv.2019.296. [PMID: 36452273 PMCID: PMC9706685 DOI: 10.1557/adv.2019.296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pulsed coherent extreme ultraviolet (EUV) radiation is a potential alternative to pulsed near-ultraviolet (NUV) wavelengths for atom probe tomography. EUV radiation has the benefit of high absorption within the first few nm of the sample surface for elements across the entire periodic table. In addition, EUV radiation may also offer athermal field ion emission pathways through direct photoionization or core-hole Auger decay processes, which are not possible with the (much lower) photon energies used in conventional NUV laser-pulsed atom probe. We report preliminary results from what we believe to be the world's first EUV radiation-pulsed atom probe microscope. The instrument consists of a femtosecond-pulsed, coherent EUV radiation source interfaced to a local electrode atom probe tomograph by means of a vacuum manifold beamline. EUV photon-assisted field ion emission (of substrate atoms) has been demonstrated on various insulating, semiconducting, and metallic specimens. Select examples are shown.
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Affiliation(s)
| | - Luis Miaja-Avila
- National Institute of Standards and Technology, Boulder, CO, USA
| | - Paul T Blanchard
- National Institute of Standards and Technology, Boulder, CO, USA
| | | | | | - Norman A Sanford
- National Institute of Standards and Technology, Boulder, CO, USA
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11
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Ndione PF, Ratcliff EL, Dey SR, Warren EL, Peng H, Holder AM, Lany S, Gorman BP, Al-Jassim MM, Deutsch TG, Zakutayev A, Ginley DS. High-Throughput Experimental Study of Wurtzite Mn 1-x Zn x O Alloys for Water Splitting Applications. ACS Omega 2019; 4:7436-7447. [PMID: 31459840 PMCID: PMC6648451 DOI: 10.1021/acsomega.8b03347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 04/02/2019] [Indexed: 05/31/2023]
Abstract
We used high-throughput experimental screening methods to unveil the physical and chemical properties of Mn1-x Zn x O wurtzite alloys and identify their appropriate composition for effective water splitting application. The Mn1-x Zn x O thin films were synthesized using combinatorial pulsed laser deposition, permitting for characterization of a wide range of compositions with x varying from 0 to 1. The solubility limit of ZnO in MnO was determined using the disappearing phase method from X-ray diffraction and X-ray fluorescence data and found to increase with decreasing substrate temperature due to kinetic limitations of the thin-film growth at relatively low temperature. Optical measurements indicate the strong reduction of the optical band gap down to 2.1 eV at x = 0.5 associated with the rock salt-to-wurtzite structural transition in Mn1-x Zn x O alloys. Transmission electron microscopy results show evidence of a homogeneous wurtzite alloy system for a broad range of Mn1-x Zn x O compositions above x = 0.4. The wurtzite Mn1-x ZnxO samples with the 0.4 < x < 0.6 range were studied as anodes for photoelectrochemical water splitting, with a maximum current density of 340 μA cm-2 for 673 nm-thick films. These Mn1-x Zn x O films were stable in pH = 10, showing no evidence of photocorrosion or degradation after 24 h under water oxidation conditions. Doping Mn1-x Zn x O materials with Ga dramatically increases the electrical conductivity of Mn1-x Zn x O up to ∼1.9 S/cm for x = 0.48, but these doped samples are not active in water splitting. Mott-Schottky and UPS/XPS measurements show that the presence of dopant atoms reduces the space charge region and increases the number of mid-gap surface states. Overall, this study demonstrates that Mn1-x Zn x O alloys hold promise for photoelectrochemical water splitting, which could be enhanced with further tailoring of their electronic properties.
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Affiliation(s)
- Paul F. Ndione
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Erin L. Ratcliff
- Department
of Materials Science and Engineering, The
University of Arizona, Tucson, Arizona 85721, United States
| | - Suhash R. Dey
- Department
of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Hyderabad 502285, India
| | - Emily L. Warren
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Haowei Peng
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Aaron M. Holder
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Stephan Lany
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Brian P. Gorman
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
- Department
of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Mowafak M. Al-Jassim
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Todd G. Deutsch
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Andriy Zakutayev
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - David S. Ginley
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
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Chen BR, Sun W, Kitchaev DA, Mangum JS, Thampy V, Garten LM, Ginley DS, Gorman BP, Stone KH, Ceder G, Toney MF, Schelhas LT. Understanding crystallization pathways leading to manganese oxide polymorph formation. Nat Commun 2018; 9:2553. [PMID: 29959330 PMCID: PMC6026189 DOI: 10.1038/s41467-018-04917-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/29/2018] [Indexed: 11/09/2022] Open
Abstract
Hydrothermal synthesis is challenging in metal oxide systems with diverse polymorphism, as reaction products are often sensitive to subtle variations in synthesis parameters. This sensitivity is rooted in the non-equilibrium nature of low-temperature crystallization, where competition between different metastable phases can lead to complex multistage crystallization pathways. Here, we propose an ab initio framework to predict how particle size and solution composition influence polymorph stability during nucleation and growth. We validate this framework using in situ X-ray scattering, by monitoring how the hydrothermal synthesis of MnO2 proceeds through different crystallization pathways under varying solution potassium ion concentrations ([K+] = 0, 0.2, and 0.33 M). We find that our computed size-dependent phase diagrams qualitatively capture which metastable polymorphs appear, the order of their appearance, and their relative lifetimes. Our combined computational and experimental approach offers a rational and systematic paradigm for the aqueous synthesis of target metal oxides.
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Affiliation(s)
- Bor-Rong Chen
- Stanford Synchrotron Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Wenhao Sun
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA, 94720, USA
| | - Daniil A Kitchaev
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - John S Mangum
- Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Vivek Thampy
- Stanford Synchrotron Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Lauren M Garten
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - David S Ginley
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Brian P Gorman
- Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Kevin H Stone
- Stanford Synchrotron Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Gerbrand Ceder
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA, 94720, USA.
| | - Michael F Toney
- Stanford Synchrotron Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Laura T Schelhas
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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Garten LM, Dwaraknath S, Walker J, Mangum JS, Ndione PF, Park Y, Beaton DA, Gopalan V, Gorman BP, Schelhas LT, Toney MF, Trolier-McKinstry S, Persson KA, Ginley DS. Theory-Guided Synthesis of a Metastable Lead-Free Piezoelectric Polymorph. Adv Mater 2018; 30:e1800559. [PMID: 29744947 DOI: 10.1002/adma.201800559] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/11/2018] [Indexed: 06/08/2023]
Abstract
Many technologically critical materials are metastable under ambient conditions, yet the understanding of how to rationally design and guide the synthesis of these materials is limited. This work presents an integrated approach that targets a metastable lead-free piezoelectric polymorph of SrHfO3 . First-principles calculations predict that the previous experimentally unrealized, metastable P4mm phase of SrHfO3 should exhibit a direct piezoelectric response (d33 ) of 36.9 pC N-1 (compared to d33 = 0 for the ground state). Combining computationally optimized substrate selection and synthesis conditions lead to the epitaxial stabilization of the polar P4mm phase of SrHfO3 on SrTiO3 . The films are structurally consistent with the theory predictions. A ferroelectric-induced large signal effective converse piezoelectric response of 5.2 pm V-1 for a 35 nm film is observed, indicating the ability to predict and target multifunctionality. This illustrates a coupled theory-experimental approach to the discovery and realization of new multifunctional polymorphs.
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Affiliation(s)
- Lauren M Garten
- National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA
| | - Shyam Dwaraknath
- Lawrence Berkeley National Laboratory/University of California Berkeley, Berkeley, CA, 94704, USA
| | - Julian Walker
- Lawrence Berkeley National Laboratory/University of California Berkeley, Berkeley, CA, 94704, USA
| | | | - Paul F Ndione
- National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA
| | - Yoonsang Park
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Daniel A Beaton
- National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA
| | - Venkatraman Gopalan
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Brian P Gorman
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Laura T Schelhas
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Michael F Toney
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Susan Trolier-McKinstry
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Kristin A Persson
- Lawrence Berkeley National Laboratory/University of California Berkeley, Berkeley, CA, 94704, USA
- Department of Materials Science and Engineering, Hearst Mining Memorial Building, UC Berkeley, Berkeley, CA, 94720, USA
| | - David S Ginley
- National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA
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Kirchhofer R, Diercks DR, Gorman BP. Electron diffraction and imaging for atom probe tomography. Rev Sci Instrum 2018; 89:053706. [PMID: 29864799 DOI: 10.1063/1.4999484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Previous work has shown that pre- and post-experiment quantification of atom probe tomography (APT) specimen geometry using electron microscopy can constrain otherwise unknown parameters, leading to an improvement in data fidelity. To that end, an electron microscopy and diffraction system has been developed for in situ compatibility with modern APT hardware. The system is capable of secondary and backscattered scanning electron imaging, bright field and dark field scanning transmission electron imaging, and scanning transmission electron diffraction. Additionally, the system is also capable of in situ dynamic electron diffraction experiments using laser pulsed heating of the APT specimen.
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Affiliation(s)
- Rita Kirchhofer
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, USA
| | - David R Diercks
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, USA
| | - Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, USA
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15
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McCoy JJ, Swain SK, Sieber JR, Diercks DR, Gorman BP, Lynn KG. p-type doping efficiency in CdTe: Influence of second phase formation. J Appl Phys 2018; 123:161579. [PMID: 29725138 PMCID: PMC5927378 DOI: 10.1063/1.5002144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Cadmium telluride (CdTe) high purity, bulk, crystal ingots doped with phosphorus were grown by the vertical Bridgman melt growth technique to understand and improve dopant solubility and activation. Large net carrier densities have been reproducibly obtained from as-grown ingots, indicating successful incorporation of dopants into the lattice. However, net carrier density values are orders of magnitude lower than the solubility of P in CdTe as reported in literature, 1018/cm3 to 1019/cm3 [J. H. Greenberg, J. Cryst. Growth 161, 1-11 (1996) and R. B. Hall and H. H. Woodbury, J. Appl. Phys. 39(12), 5361-5365 (1968)], despite comparable starting charge dopant densities. Growth conditions, such as melt stoichiometry and post growth cooling, are shown to have significant impacts on dopant solubility. This study demonstrates that a significant portion of the dopant becomes incorporated into second phase defects as compounds of cadmium and phosphorous, such as cadmium phosphide, which inhibits dopant incorporation into the lattice and limits maximum attainable net carrier density in bulk crystals. Here, we present an extensive study on the characteristics of these second phase defects in relation to their composition and formation kinetics while providing a pathway to minimize their formation and enhance solubility.
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Affiliation(s)
- Jedidiah J McCoy
- Center for Materials Research, Washington State University, Pullman, Washington 99164, USA
| | - Santosh K Swain
- Center for Materials Research, Washington State University, Pullman, Washington 99164, USA
| | - John R Sieber
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | | | | | - Kelvin G Lynn
- Center for Materials Research, Washington State University, Pullman, Washington 99164, USA
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16
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Mangum JS, Chan LH, Schmidt U, Garten LM, Ginley DS, Gorman BP. Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs. Ultramicroscopy 2018; 188:48-51. [PMID: 29549789 DOI: 10.1016/j.ultramic.2018.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 11/19/2022]
Abstract
Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.
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Affiliation(s)
- John S Mangum
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, USA.
| | | | | | - Lauren M Garten
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
| | - David S Ginley
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
| | - Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, USA.
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17
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Haggerty JES, Schelhas LT, Kitchaev DA, Mangum JS, Garten LM, Sun W, Stone KH, Perkins JD, Toney MF, Ceder G, Ginley DS, Gorman BP, Tate J. High-fraction brookite films from amorphous precursors. Sci Rep 2017; 7:15232. [PMID: 29123137 PMCID: PMC5680313 DOI: 10.1038/s41598-017-15364-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/25/2017] [Indexed: 11/26/2022] Open
Abstract
Structure-specific synthesis processes are of key importance to the growth of polymorphic functional compounds such as TiO2, where material properties strongly depend on structure as well as chemistry. The robust growth of the brookite polymorph of TiO2, a promising photocatalyst, has been difficult in both powder and thin-film forms due to the disparity of reported synthesis techniques, their highly specific nature, and lack of mechanistic understanding. In this work, we report the growth of high-fraction (~95%) brookite thin films prepared by annealing amorphous titania precursor films deposited by pulsed laser deposition. We characterize the crystallization process, eliminating the previously suggested roles of substrate templating and Na helper ions in driving brookite formation. Instead, we link phase selection directly to film thickness, offering a novel, generalizable route to brookite growth that does not rely on the presence of extraneous elements or particular lattice-matched substrates. In addition to providing a new synthesis route to brookite thin films, our results take a step towards resolving the problem of phase selection in TiO2 growth, contributing to the further development of this promising functional material.
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Affiliation(s)
- James E S Haggerty
- Department of Physics, Oregon State University, Corvallis, OR, 97331, USA
| | - Laura T Schelhas
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Daniil A Kitchaev
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - John S Mangum
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Lauren M Garten
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Wenhao Sun
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA, 94720, USA
| | - Kevin H Stone
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - John D Perkins
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Michael F Toney
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Gerbrand Ceder
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA, 94720, USA
| | - David S Ginley
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Brian P Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Janet Tate
- Department of Physics, Oregon State University, Corvallis, OR, 97331, USA.
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18
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Xiao C, Wang C, Ke W, Gorman BP, Ye J, Jiang CS, Yan Y, Al-Jassim MM. Junction Quality of SnO 2-Based Perovskite Solar Cells Investigated by Nanometer-Scale Electrical Potential Profiling. ACS Appl Mater Interfaces 2017; 9:38373-38380. [PMID: 29027466 DOI: 10.1021/acsami.7b08582] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on the cross section of SnO2-based PS solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having an identical device structure: (1) cells with PS deposited directly on bare fluorine-doped SnO2 (FTO)-coated glass; (2) cells with an intrinsic SnO2 thin layer on the top of FTO as an effective ESL; and (3) cells with the SnO2 ESL and adding a self-assembled monolayer (SAM) of fullerene. The results reveal two major potential drops or electric fields at the ESL/PS and PS/HSL interfaces. The electric-field ratio between the ESL/PS and PS/HSL interfaces increased in devices as follows: FTO < SnO2-ESL < SnO2 + SAM; this sequence explains the improvements of the fill factor (FF) and open-circuit voltage (Voc). The improvement of the FF from the FTO to SnO2-ESL cells may result from the reduction in voltage loss at the PS/HSL back interface and the improvement of Voc from the prevention of hole recombination at the ESL/PS front interface. The further improvements with adding an SAM is caused by the defect passivation at the ESL/PS interface, and hence, improvement of the junction quality. These nanoelectrical findings suggest possibilities for improving the device performance by further optimizing the SnO2-based ESL material quality and the ESL/PS interface.
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Affiliation(s)
- Chuanxiao Xiao
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
- Colorado School of Mines , Golden, Colorado 80401, United States
| | - Changlei Wang
- The University of Toledo , Toledo, Ohio 43606, United States
| | - Weijun Ke
- The University of Toledo , Toledo, Ohio 43606, United States
| | - Brian P Gorman
- Colorado School of Mines , Golden, Colorado 80401, United States
| | - Jichun Ye
- Ningbo Institute of Industrial Technology, Chinese Academy of Science , Ningbo, Zhejiang Province 315201, China
| | - Chun-Sheng Jiang
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
| | - Yanfa Yan
- The University of Toledo , Toledo, Ohio 43606, United States
| | - Mowafak M Al-Jassim
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
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19
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Holder AM, Siol S, Ndione PF, Peng H, Deml AM, Matthews BE, Schelhas LT, Toney MF, Gordon RG, Tumas W, Perkins JD, Ginley DS, Gorman BP, Tate J, Zakutayev A, Lany S. Novel phase diagram behavior and materials design in heterostructural semiconductor alloys. Sci Adv 2017; 3:e1700270. [PMID: 28630928 PMCID: PMC5462504 DOI: 10.1126/sciadv.1700270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/12/2017] [Indexed: 05/28/2023]
Abstract
Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the critical composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region.
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Affiliation(s)
- Aaron M. Holder
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA
| | - Sebastian Siol
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Paul F. Ndione
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Haowei Peng
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Ann M. Deml
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | | | - Laura T. Schelhas
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Michael F. Toney
- Applied Energy Programs, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Roy G. Gordon
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - William Tumas
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | | | | | - Brian P. Gorman
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Janet Tate
- Department of Physics, Oregon State University, Corvallis, OR 97331, USA
| | | | - Stephan Lany
- National Renewable Energy Laboratory, Golden, CO 80401, USA
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20
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Abstract
Six precursors were evaluated for use as in situ electron beam-induced deposition capping layers in the preparation of atom probe tomography specimens with a focus on near-surface features where some of the deposition is retained at the specimen apex. Specimens were prepared by deposition of each precursor onto silicon posts and shaped into sub-70-nm radii needles using a focused ion beam. The utility of the depositions was assessed using several criteria including composition and uniformity, evaporation behavior and evaporation fields, and depth of Ga+ ion penetration. Atom probe analyses through depositions of methyl cyclopentadienyl platinum trimethyl, palladium hexafluoroacetylacetonate, and dimethyl-gold-acetylacetonate [Me2Au(acac)] were all found to result in tip fracture at voltages exceeding 3 kV. Examination of the deposition using Me2Au(acac) plus flowing O2 was inconclusive due to evaporation of surface silicon from below the deposition under all analysis conditions. Dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9] depositions were found to be effective as in situ capping materials for the silicon specimens. Their very different evaporation fields [36 V/nm for Co2(CO)8 and 21 V/nm for Fe2(CO)9] provide options for achieving reasonably close matching of the evaporation field between the capping material and many materials of interest.
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Affiliation(s)
- David R Diercks
- 1Department of Metallurgical and Materials Engineering,Colorado School of Mines,Golden,CO 80401,USA
| | - Brian P Gorman
- 1Department of Metallurgical and Materials Engineering,Colorado School of Mines,Golden,CO 80401,USA
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21
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Clark DR, Zhu H, Diercks DR, Ricote S, Kee RJ, Almansoori A, Gorman BP, O'Hayre RP. Probing Grain-Boundary Chemistry and Electronic Structure in Proton-Conducting Oxides by Atom Probe Tomography. Nano Lett 2016; 16:6924-6930. [PMID: 27696864 DOI: 10.1021/acs.nanolett.6b02918] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A laser-assisted atom-probe-tomographic (LAAPT) method has been developed and applied to measure and characterize the three-dimensional atomic and electronic nanostructure at an yttrium-doped barium zirconate (BaZr0.9Y0.1O3-δ, BZY10) grain boundary. Proton-conducting perovskites, such as BZY10, are attracting intense interest for a variety of energy conversion applications. However, their implementation has been hindered, in part, because of high grain-boundary (GB) resistance that is attributed to a positive GB space-charge layer (SCL). In this study, LAAPT is used to analyze BZY10 GB chemistry in three dimensions with subnanometer resolution. From this analysis, maps of the charge density and electrostatic potential arising at the GBs are derived, revealing for the first time direct chemical evidence that a positive SCL indeed exists at these GBs. These maps reveal new insights on the inhomogeneity of the SCL region and produce an average GB potential barrier of approximately 580 mV, agreeing with previous indirect electrochemical measurements.
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Affiliation(s)
- Daniel R Clark
- Renewable Energy Materials Research Science and Engineering Center (REMRSEC), Colorado School of Mines , 1500 Illinois St., Golden, Colorado 80401, United States
- Center for Advanced Ceramics, Metallurgical and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Huayang Zhu
- Department of Mechanical Engineering, Colorado School of Mines , 1500 Illinois St., Golden, Colorado 80401, United States
| | - David R Diercks
- Center for Advanced Ceramics, Metallurgical and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Sandrine Ricote
- Department of Mechanical Engineering, Colorado School of Mines , 1500 Illinois St., Golden, Colorado 80401, United States
| | - Robert J Kee
- Department of Mechanical Engineering, Colorado School of Mines , 1500 Illinois St., Golden, Colorado 80401, United States
| | - Ali Almansoori
- Department of Chemical Engineering, The Petroleum Institute , Post Office Box 2533, Abu Dhabi, United Arab Emirates
| | - Brian P Gorman
- Center for Advanced Ceramics, Metallurgical and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Ryan P O'Hayre
- Renewable Energy Materials Research Science and Engineering Center (REMRSEC), Colorado School of Mines , 1500 Illinois St., Golden, Colorado 80401, United States
- Center for Advanced Ceramics, Metallurgical and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
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22
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Proudian AP, Jaskot MB, Lyiza C, Diercks DR, Gorman BP, Zimmerman JD. Effect of Diels-Alder Reaction in C 60-Tetracene Photovoltaic Devices. Nano Lett 2016; 16:6086-6091. [PMID: 27575667 DOI: 10.1021/acs.nanolett.6b02238] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Developing organic photovoltaic materials systems requires a detailed understanding of the heterojunction interface, as it is the foundation for photovoltaic device performance. The bilayer fullerene/acene system is one of the most studied models for testing our understanding of this interface. We demonstrate that the fullerene and acene molecules chemically react at the heterojunction interface, creating a partial monolayer of a Diels-Alder cycloadduct species. Furthermore, we show that the reaction occurs during standard deposition conditions and that thermal annealing increases the concentration of the cycloadduct. The cycloaddition reaction reduces the number of sites available at the interface for charge transfer exciton recombination and decreases the charge transfer state reorganization energy, increasing the open circuit voltage. The submonolayer quantity of the cycloadduct renders it difficult to identify with conventional characterization techniques; we use atom probe tomography to overcome this limitation while also measuring the spatial distribution of each chemical species.
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Affiliation(s)
- Andrew P Proudian
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Matthew B Jaskot
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Christelle Lyiza
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - David R Diercks
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Brian P Gorman
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Jeramy D Zimmerman
- Department of Physics, ‡Materials Science Program, and §Department of Metallurgy and Materials Engineering, Colorado School of Mines , Golden, Colorado 80401, United States
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23
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Zhou T, Anderson RT, Li H, Bell J, Yang Y, Gorman BP, Pylypenko S, Lusk MT, Sellinger A. Bandgap Tuning of Silicon Quantum Dots by Surface Functionalization with Conjugated Organic Groups. Nano Lett 2015; 15:3657-3663. [PMID: 25971956 DOI: 10.1021/nl504051x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The quantum confinement and enhanced optical properties of silicon quantum dots (SiQDs) make them attractive as an inexpensive and nontoxic material for a variety of applications such as light emitting technologies (lighting, displays, sensors) and photovoltaics. However, experimental demonstration of these properties and practical application into optoelectronic devices have been limited as SiQDs are generally passivated with covalently bound insulating alkyl chains that limit charge transport. In this work, we show that strategically designed triphenylamine-based surface ligands covalently bonded to the SiQD surface using conjugated vinyl connectivity results in a 70 nm red-shifted photoluminescence relative to their decyl-capped control counterparts. This suggests that electron density from the SiQD is delocalized into the surface ligands to effectively create a larger hybrid QD with possible macroscopic charge transport properties.
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Affiliation(s)
- Tianlei Zhou
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Ryan T Anderson
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Huashan Li
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Jacob Bell
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Yongan Yang
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Brian P Gorman
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Svitlana Pylypenko
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Mark T Lusk
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Alan Sellinger
- †Department of Chemistry and Geochemistry, ‡Department of Physics, §Materials Science Program, ∥Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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24
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Polley CM, Clarke WR, Miwa JA, Scappucci G, Wells JW, Jaeger DL, Bischof MR, Reidy RF, Gorman BP, Simmons M. Exploring the limits of N-type ultra-shallow junction formation. ACS Nano 2013; 7:5499-5505. [PMID: 23721101 DOI: 10.1021/nn4016407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Low resistivity, near-surface doping in silicon represents a formidable challenge for both the microelectronics industry and future quantum electronic devices. Here we employ an ultra-high vacuum strategy to create highly abrupt doping profiles in silicon, which we characterize in situ using a four point probe scanning tunnelling microscope. Using a small molecule gaseous dopant source (PH3) which densely packs on a reconstructed silicon surface, followed by encapsulation in epitaxial silicon, we form highly conductive dopant sheets with subnanometer control of the depth profiles. This approach allows us to test the limits of ultra-shallow junction formation, with room temperature resistivities of 780 Ω/□ at an encapsulation depth of 4.3 nm, increasing to 23 kΩ/□ at an encapsulation depth of only 0.5 nm. We show that this depth-dependent resistivity can be accounted for by a combination of dopant segregation and surface scattering.
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Affiliation(s)
- Craig M Polley
- School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia.
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25
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Scappucci G, Klesse WM, Hamilton AR, Capellini G, Jaeger DL, Bischof MR, Reidy RF, Gorman BP, Simmons MY. Stacking of 2D electron gases in Ge probed at the atomic level and its correlation to low-temperature magnetotransport. Nano Lett 2012; 12:4953-4959. [PMID: 22935029 DOI: 10.1021/nl302558b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Stacking of two-dimensional electron gases (2DEGs) obtained by δ-doping of Ge and patterned by scanning probe lithography is a promising approach to realize ultrascaled 3D epitaxial circuits, where multiple layers of active electronic components are integrated both vertically and horizontally. We use atom probe tomography and magnetotransport to correlate the real space 3D atomic distribution of dopants in the crystal with the quantum correction to the conductivity observed at low temperatures, probing if closely stacked δ-layers in Ge behave as independent 2DEGs. We find that at a separation of 9 nm the stacked-2DEGs, while interacting, still maintain their individuality in terms of electron transport and show long phase coherence lengths (∼220 nm). Strong vertical electron confinement is crucial to this finding, resulting in an interlayer scattering time much longer (∼1000 × ) than the scattering time within the dopant plane.
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Affiliation(s)
- G Scappucci
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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26
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Gorman BP, Norman AG, Yan Y. Atom probe analysis of III-V and Si-based semiconductor photovoltaic structures. Microsc Microanal 2007; 13:493-502. [PMID: 18001514 DOI: 10.1017/s1431927607070894] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 08/16/2007] [Indexed: 05/25/2023]
Abstract
The applicability of atom probe to the characterization of photovoltaic devices is presented with special emphasis on high efficiency III-V and low cost ITO/a-Si:H heterojunction cells. Laser pulsed atom probe is shown to enable subnanometer chemical and structural depth profiling of interfaces in III-V heterojunction cells. Hydrogen, oxygen, and phosphorus chemical profiling in 5-nm-thick a-Si heterojunction cells is also illustrated, along with compositional analysis of the ITO/a-Si interface. Detection limits of atom probe tomography useful to semiconductor devices are also discussed. Gaining information about interfacial abruptness, roughness, and dopant profiles will allow for the determination of semiconductor conductivity, junction depletion widths, and ultimately photocurrent collection efficiencies and fill factors.
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Affiliation(s)
- Brian P Gorman
- Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA.
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