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Hilliard D, Tauchnitz T, Hübner R, Vasileiadis I, Gkotinakos A, Dimitrakopulos G, Komninou P, Sun X, Winnerl S, Schneider H, Helm M, Dimakis E. At the Limit of Interfacial Sharpness in Nanowire Axial Heterostructures. ACS NANO 2024; 18:21171-21183. [PMID: 38970499 PMCID: PMC11328169 DOI: 10.1021/acsnano.4c04172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/08/2024]
Abstract
As semiconductor devices approach dimensions at the atomic scale, controlling the compositional grading across heterointerfaces becomes paramount. Particularly in nanowire axial heterostructures, which are promising for a broad spectrum of nanotechnology applications, the achievement of sharp heterointerfaces has been challenging owing to peculiarities of the commonly used vapor-liquid-solid growth mode. Here, the grading of Al across GaAs/AlxGa1-xAs/GaAs heterostructures in self-catalyzed nanowires is studied, aiming at finding the limits of the interfacial sharpness for this technologically versatile material system. A pulsed growth mode ensures precise control of the growth mechanisms even at low temperatures, while a semiempirical thermodynamic model is derived to fit the experimental Al-content profiles and quantitatively describe the dependences of the interfacial sharpness on the growth temperature, the nanowire radius, and the Al content. Finally, symmetrical Al profiles with interfacial widths of 2-3 atomic planes, at the limit of the measurement accuracy, are obtained, outperforming even equivalent thin-film heterostructures. The proposed method enables the development of advanced heterostructure schemes for a more effective utilization of the nanowire platform; moreover, it is considered expandable to other material systems and nanostructure types.
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Affiliation(s)
- Donovan Hilliard
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- TUD Dresden University of Technology, Dresden 01062, Germany
| | - Tina Tauchnitz
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- TUD Dresden University of Technology, Dresden 01062, Germany
| | - René Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Isaak Vasileiadis
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Athanasios Gkotinakos
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - George Dimitrakopulos
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Philomela Komninou
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Xiaoxiao Sun
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Stephan Winnerl
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Harald Schneider
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Manfred Helm
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
- TUD Dresden University of Technology, Dresden 01062, Germany
| | - Emmanouil Dimakis
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
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Al Hassan A, AlHumaidi M, Kalt J, Schneider R, Müller E, Anjum T, Khadiev A, Novikov DV, Pietsch U, Baumbach T. Bending and reverse bending during the fabrication of novel GaAs/(In,Ga)As/GaAs core-shell nanowires monitored by in situx-ray diffraction. NANOTECHNOLOGY 2024; 35:295705. [PMID: 38631325 DOI: 10.1088/1361-6528/ad3fc1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
We report on the fabrication of a novel design of GaAs/(In,Ga)As/GaAs radial nanowire heterostructures on a Si 111 substrate, where, for the first time, the growth of inhomogeneous shells on a lattice mismatched core results in straight nanowires instead of bent. Nanowire bending caused by axial tensile strain induced by the (In,Ga)As shell on the GaAs core is reversed by axial compressive strain caused by the GaAs outer shell on the (In,Ga)As shell. Progressive nanowire bending and reverse bending in addition to the axial strain evolution during the two processes are accessed byin situby x-ray diffraction. The diameter of the core, thicknesses of the shells, as well as the indium concentration and distribution within the (In,Ga)As quantum well are revealed by 2D energy dispersive x-ray spectroscopy using a transmission electron microscope. Shell(s) growth on one side of the core without substrate rotation results in planar-like radial heterostructures in the form of free standing straight nanowires.
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Affiliation(s)
- Ali Al Hassan
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Mahmoud AlHumaidi
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, Kaiserstraße 12, D-76131 Karlsruhe, Germany
| | - Jochen Kalt
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, Kaiserstraße 12, D-76131 Karlsruhe, Germany
| | - Reinhard Schneider
- Laboratory for Electron Microscopy, Karlsruhe Institute for Technology, D-76128 Karlsruhe, Germany
| | - Erich Müller
- Laboratory for Electron Microscopy, Karlsruhe Institute for Technology, D-76128 Karlsruhe, Germany
| | - Taseer Anjum
- Solid State Physics, University of Siegen, Walter-Flex Straße 3, D-57068, Siegen, Germany
| | - Azat Khadiev
- DESY Photon Science, Notkestr. 85, D-22607 Hamburg, Germany
| | | | - Ullrich Pietsch
- Solid State Physics, University of Siegen, Walter-Flex Straße 3, D-57068, Siegen, Germany
| | - Tilo Baumbach
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology, Kaiserstraße 12, D-76131 Karlsruhe, Germany
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Wan Y, Sun P, Shi L, Yan X, Zhang X. Three-Dimensional Fully Conjugated Covalent Organic Frameworks for Efficient Photocatalytic Water Splitting. J Phys Chem Lett 2023; 14:7411-7420. [PMID: 37578869 DOI: 10.1021/acs.jpclett.3c01850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
Covalent organic frameworks (COFs) are promising photocatalysts for water splitting, but their efficiency lags behind that of inorganic counterparts partly due to the limited charge transport and optical absorption properties. To overcome this limitation, we proposed to employ three-dimensional (3D) fully conjugated (FC) COFs with a topological assembly of cyclooctatetraene derivatives for photocatalytic water splitting. On the basis of first-principles calculations, we demonstrated that these 3D FC-COFs are semiconductors with exceptional charge transport and optical absorption properties. The carrier mobilities are comparable to those of inorganic semiconductors and superior to the record mobility observed in two-dimensional COFs. Additionally, the 3D FC-COFs exhibit broad visible light absorption with direct band gaps and high optical absorption coefficients. Among them, two 3D FC-COFs are identified for overall water splitting, while three others can facilitate the hydrogen evolution half-reaction. This study pioneers the design of 3D FC-COF photocatalysts, potentially advancing their applications in photocatalysis and optoelectronics.
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Affiliation(s)
- Yangyang Wan
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Pengting Sun
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Lebin Shi
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Xiaohong Yan
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Xu Zhang
- Department of Physics and Astronomy, California State University Northridge, Northridge, California 91330-8268, United States
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Hill MO, Schmiedeke P, Huang C, Maddali S, Hu X, Hruszkewycz SO, Finley JJ, Koblmüller G, Lauhon LJ. 3D Bragg Coherent Diffraction Imaging of Extended Nanowires: Defect Formation in Highly Strained InGaAs Quantum Wells. ACS NANO 2022; 16:20281-20293. [PMID: 36378999 DOI: 10.1021/acsnano.2c06071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
InGaAs quantum wells embedded in GaAs nanowires can serve as compact near-infrared emitters for direct integration onto Si complementary metal oxide semiconductor technology. While the core-shell geometry in principle allows for a greater tuning of composition and emission, especially farther into the infrared, the practical limits of elastic strain accommodation in quantum wells on multifaceted nanowires have not been established. One barrier to progress is the difficulty of directly comparing the emission characteristics and the precise microstructure of a single nanowire. Here we report an approach to correlating quantum well morphology, strain, defects, and emission to understand the limits of elastic strain accommodation in nanowire quantum wells specific to their geometry. We realize full 3D Bragg coherent diffraction imaging (BCDI) of intact quantum wells on vertically oriented epitaxial nanowires, which enables direct correlation with single-nanowire photoluminescence. By growing In0.2Ga0.8As quantum wells of distinct thicknesses on different facets of the same nanowire, we identified the critical thickness at which defects are nucleated. A correlation with a traditional transmission electron microscopy analysis confirms that BCDI can image the extended structure of defects. Finite element simulations of electron and hole states explain the emission characteristics arising from strained and partially relaxed regions. This approach, imaging the 3D strain and microstructure of intact nanowire core-shell structures with application-relevant dimensions, can aid the development of predictive models that enable the design of new compact infrared emitters.
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Affiliation(s)
- Megan O Hill
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Paul Schmiedeke
- Walter Schottky Institute and Physics Department, Technical University of Munich, Garching85748, Germany
| | - Chunyi Huang
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Siddharth Maddali
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois60439, United States
| | - Xiaobing Hu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
- The NUANCE Center, Northwestern University, Evanston, Illinois60208, United States
| | - Stephan O Hruszkewycz
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois60439, United States
| | - Jonathan J Finley
- Walter Schottky Institute and Physics Department, Technical University of Munich, Garching85748, Germany
| | - Gregor Koblmüller
- Walter Schottky Institute and Physics Department, Technical University of Munich, Garching85748, Germany
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
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Effect of Si(111) Surface Modification by Ga Focused Ion Beam at 30 kV on GaAs Nanowire Growth. Int J Mol Sci 2022; 24:ijms24010224. [PMID: 36613671 PMCID: PMC9820241 DOI: 10.3390/ijms24010224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/10/2022] [Accepted: 12/20/2022] [Indexed: 12/25/2022] Open
Abstract
This paper presents the results of experimental studies of the effect of Si(111) surface modification by Ga-focused ion beam (FIB) at 30 kV accelerating voltage on the features of the epitaxial GaAs nanowire (NW) growth processes. We experimentally established the regularities of the Ga ions' dose effect during surface modification on the structural characteristics of GaAs NW arrays. Depending on the Ga ion dose value, there is one of three modes on the surface for subsequent GaAs NW growth. At low doses, the NW growth is almost completely suppressed. The growth mode of high-density (up to 6.56 µm-2) GaAs NW arrays with a maximum fraction (up to 70%) of nanowires normally oriented to the substrate is realized in the medium ion doses range. A continuous polycrystalline base with a dense array of misoriented short (up to 0.9 µm) and thin (up to 27 nm) GaAs NWs is formed at high doses. We assume that the key role is played by the interaction of the implanted Ga ions with the surface at various process stages and its influence on the surface structure in the modification region and on GaAs NW growth conditions.
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Thickness Effect on the Solid-State Reaction of a Ni/GaAs System. NANOMATERIALS 2022; 12:nano12152633. [PMID: 35957063 PMCID: PMC9370099 DOI: 10.3390/nano12152633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 12/10/2022]
Abstract
Ni thin films with different thicknesses were grown on a GaAs substrate using the magnetron sputtering technique followed by in situ X-ray diffraction (XRD) annealing in order to study the solid-state reaction between Ni and GaAs substrate. The thickness dependence on the formation of the intermetallic phases was investigated using in situ and ex situ XRD, pole figures, and atom probe tomography (APT). The results indicate that the 20 nm-thick Ni film exhibits an epitaxial relation with the GaAs substrate, which is (001) Ni//(001) GaAs and [111] Ni//[110] GaAs after deposition. Increasing the film’s thickness results in a change of the Ni film’s texture. This difference has an impact on the formation temperature of Ni3GaAs. This temperature decreases simultaneously with the thickness increase. This is due to the coherent/incoherent nature of the initial Ni/GaAs interface. The Ni3GaAs phase decomposes into the binary and ternary compounds xNiAs and Ni3−xGaAs1−x at about 400 °C. Similarly to Ni3GaAs, the decomposition temperature of the second phase also depends on the initial thickness of the Ni layer.
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Yuan L, Pokharel R, Devkota S, Kuchoor H, Dawkins K, Lee MC, Huang Y, Yarotski D, Iyer S, Prasankumar RP. Revealing charge carrier dynamics and transport in Te-doped GaAsSb and GaAsSbN nanowires by correlating ultrafast terahertz spectroscopy and optoelectronic characterization. NANOTECHNOLOGY 2022; 33:425702. [PMID: 35772308 DOI: 10.1088/1361-6528/ac7d61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Abstract
Recent advances in the growth of III-V semiconductor nanowires (NWs) hold great promise for nanoscale optoelectronic device applications. It is established that a small amount of nitrogen (N) incorporation in III-V semiconductor NWs can effectively red-shift their wavelength of operation and tailor their electronic properties for specific applications. However, understanding the impact of N incorporation on non-equilibrium charge carrier dynamics and transport in semiconducting NWs is critical in achieving efficient semiconducting NW devices. In this work, ultrafast optical pump-terahertz probe spectroscopy has been used to study non-equilibrium carrier dynamics and transport in Te-doped GaAsSb and dilute nitride GaAsSbN NWs, with the goal of correlating these results with electrical characterization of their equilibrium photo-response under bias and low-frequency noise characteristics. Nitrogen incorporation in GaAsSb NWs led to a significant increase in the carrier scattering rate, resulting in a severe reduction in carrier mobility. Carrier recombination lifetimes of 33 ± 1 picoseconds (ps) and 147 ± 3 ps in GaAsSbN and GaAsSb NWs, respectively, were measured. The reduction in the carrier lifetime and photoinduced optical conductivities are due to the presence of N-induced defects, leading to deterioration in the electrical and optical characteristics of dilute nitride NWs relative to the non-nitride NWs. Finally, we observed a very fast rise time of ∼2 ps for both NW materials, directly impacting their potential use as high-speed photodetectors.
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Affiliation(s)
- Long Yuan
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - Rabin Pokharel
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T University, Greensboro, NC 27401, United States of America
| | - Shisir Devkota
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T University, Greensboro, NC 27401, United States of America
| | - Hirandeep Kuchoor
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T University, Greensboro, NC 27401, United States of America
| | - Kendall Dawkins
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T University, Greensboro, NC 27401, United States of America
| | - Min-Cheol Lee
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - Yue Huang
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - Dzmitry Yarotski
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - Shanthi Iyer
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T University, Greensboro, NC 27401, United States of America
| | - Rohit P Prasankumar
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
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