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Jeong HW, Ajay A, Döblinger M, Sturm S, Gómez Ruiz M, Zell R, Mukhundhan N, Stelzner D, Lähnemann J, Müller-Caspary K, Finley JJ, Koblmüller G. Axial Growth Characteristics of Optically Active InGaAs Nanowire Heterostructures for Integrated Nanophotonic Devices. ACS Appl Nano Mater 2024; 7:3032-3041. [PMID: 38357219 PMCID: PMC10863613 DOI: 10.1021/acsanm.3c05392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/21/2023] [Accepted: 12/26/2023] [Indexed: 02/16/2024]
Abstract
III-V semiconductor nanowire (NW) heterostructures with axial InGaAs active regions hold large potential for diverse on-chip device applications, including site-selectively integrated quantum light sources, NW lasers with high material gain, as well as resonant tunneling diodes and avalanche photodiodes. Despite various promising efforts toward high-quality single or multiple axial InGaAs heterostacks using noncatalytic growth mechanisms, the important roles of facet-dependent shape evolution, crystal defects, and the applicability to more universal growth schemes have remained elusive. Here, we report the growth of optically active InGaAs axial NW heterostructures via completely catalyst-free, selective-area molecular beam epitaxy directly on silicon (Si) using GaAs(Sb) NW arrays as tunable, high-uniformity growth templates and highlight fundamental relationships between structural, morphological, and optical properties of the InGaAs region. Structural, compositional, and 3D-tomographic characterizations affirm the desired directional growth along the NW axis with no radial growth observed. Clearly distinct luminescence from the InGaAs active region is demonstrated, where tunable array-geometry parameters and In content up to 20% are further investigated. Based on the underlying twin-induced growth mode, we further describe the facet-dependent shape and interface evolution of the InGaAs segment and its direct correlation with emission energy.
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Affiliation(s)
- Hyowon W. Jeong
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
| | - Akhil Ajay
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
| | - Markus Döblinger
- Department
of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Sebastian Sturm
- Department
of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Mikel Gómez Ruiz
- Paul-Drude-Institute
for Solid State Electronics, Leibniz-Institut
Im Forschungsverbund Berlin e.V., 10117 Berlin, Germany
| | - Richard Zell
- Department
of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Nitin Mukhundhan
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
| | - Daniel Stelzner
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
| | - Jonas Lähnemann
- Paul-Drude-Institute
for Solid State Electronics, Leibniz-Institut
Im Forschungsverbund Berlin e.V., 10117 Berlin, Germany
| | - Knut Müller-Caspary
- Department
of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Jonathan J. Finley
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
| | - Gregor Koblmüller
- Walter
Schottky Institute, TUM School of Natural Sciences, Technical University of Munich, 85748 Garching bei München, Germany
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2
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Hou Y, Papadopoulos I, Bo Y, Wollny AS, Ferguson MJ, Mai LA, Tykwinski RR, Guldi DM. Catalyzing Singlet Fission by Transition Metals: Second versus Third Row Effects. Precis Chem 2023; 1:555-564. [PMID: 38037593 PMCID: PMC10685717 DOI: 10.1021/prechem.3c00082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 12/02/2023]
Abstract
The synthesis and characterization of platinum(II) and palladium(II) complexes bearing two (dimers Pt(Lpc)2Cl2 and Pd(Lpc)2Cl2), one (monomers Pt(Lpc)(Lref)Cl2 and Pd(Lpc)(Lref)Cl2), or no (reference compounds Pt(Lref)2Cl2 and Pd(Lref)2Cl2) pentacene-based pyridyl ligands are presented. Photophysical properties of the dimers are probed by means of steady-state and time-resolved transient absorption measurements in comparison to the monomer and model compounds. Our results document that despite enhanced spin-orbit coupling from the presence of heavy atoms, intramolecular singlet fission (iSF) is not challenged by intersystem crossing. iSF thus yields correlated triplet pairs and even uncorrelated triplet excited states upon decoherence. Importantly, significant separation of the two pentacenyl groups facilitates decoupling of the two chromophores. Furthermore, the mechanism of iSF is altered depending on the respective metal center, that is, Pt(II) versus Pd(II). The dimer based on Pt(II), Pt(Lpc)2Cl2, exhibits a direct pathway for the iSF and forms a correlated triplet pair with singlet-quintet spin-mixing within 10 ns in variable solvents. On the other hand, the dimer based on Pd(II), Pd(Lpc)2Cl2, leads to charge transfer mixing during the population of the correlated triplet pair that is dependent on solvent polarity. Moreover, Pd(Lpc)2Cl2 gives rise to a stable equilibrium between singlet and quintet correlated triplet pairs with lifetimes of up to 170 ns. Inherent differences in the size and polarizability, when contrasting platinum(II) with palladium(II), are the most likely rationale for the underlying trends.
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Affiliation(s)
- Yuxuan Hou
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Ilias Papadopoulos
- Department
of Chemistry and Pharmacy & Interdisciplinary Center for Molecular
Materials (ICMM), Friedrich-Alexander-University
Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Yifan Bo
- Department
of Chemistry and Pharmacy & Interdisciplinary Center for Molecular
Materials (ICMM), Friedrich-Alexander-University
Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Anna-Sophie Wollny
- Department
of Chemistry and Pharmacy & Interdisciplinary Center for Molecular
Materials (ICMM), Friedrich-Alexander-University
Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Michael J. Ferguson
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Lukas A. Mai
- Department
of Chemistry and Pharmacy & Interdisciplinary Center for Molecular
Materials (ICMM), Friedrich-Alexander-University
Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Rik R. Tykwinski
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Dirk M. Guldi
- Department
of Chemistry and Pharmacy & Interdisciplinary Center for Molecular
Materials (ICMM), Friedrich-Alexander-University
Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany
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3
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Luo S, Mancini A, Wang F, Liu J, Maier SA, de Mello JC. High-Throughput Fabrication of Triangular Nanogap Arrays for Surface-Enhanced Raman Spectroscopy. ACS Nano 2022; 16:7438-7447. [PMID: 35381178 PMCID: PMC9134500 DOI: 10.1021/acsnano.1c09930] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 04/01/2022] [Indexed: 05/31/2023]
Abstract
Squeezing light into nanometer-sized metallic nanogaps can generate extremely high near-field intensities, resulting in dramatically enhanced absorption, emission, and Raman scattering of target molecules embedded within the gaps. However, the scarcity of low-cost, high-throughput, and reproducible nanogap fabrication methods offering precise control over the gap size is a continuing obstacle to practical applications. Using a combination of molecular self-assembly, colloidal nanosphere lithography, and physical peeling, we report here a high-throughput method for fabricating large-area arrays of triangular nanogaps that allow the gap width to be tuned from ∼10 to ∼3 nm. The nanogap arrays function as high-performance substrates for surface-enhanced Raman spectroscopy (SERS), with measured enhancement factors as high as 108 relative to a thin gold film. Using the nanogap arrays, methylene blue dye molecules can be detected at concentrations as low as 1 pM, while adenine biomolecules can be detected down to 100 pM. We further show that it is possible to achieve sensitive SERS detection on binary-metal nanogap arrays containing gold and platinum, potentially extending SERS detection to the investigation of reactive species at platinum-based catalytic and electrochemical surfaces.
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Affiliation(s)
- Sihai Luo
- Department
of Chemistry, Norwegian University of Science
and Technology (NTNU), 7491 Trondheim, Norway
| | - Andrea Mancini
- Chair
in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, 80539 München, Germany
| | - Feng Wang
- Department
of Structural Engineering, Norwegian University
of Science and Technology (NTNU), Trondheim 7491, Norway
| | - Junyang Liu
- College
of Chemistry and Chemical Engineering, Xiamen
University, Xiamen 361005, China
| | - Stefan A. Maier
- Chair
in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, 80539 München, Germany
- Blackett
Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ, United Kingdom
| | - John C. de Mello
- Department
of Chemistry, Norwegian University of Science
and Technology (NTNU), 7491 Trondheim, Norway
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Almora O, Matt GJ, These A, Kanak A, Levchuk I, Shrestha S, Osvet A, Brabec CJ, Garcia-Belmonte G. Surface versus Bulk Currents and Ionic Space-Charge Effects in CsPbBr 3 Single Crystals. J Phys Chem Lett 2022; 13:3824-3830. [PMID: 35466679 PMCID: PMC9082610 DOI: 10.1021/acs.jpclett.2c00804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/11/2022] [Indexed: 06/01/2023]
Abstract
CsPbBr3 single crystals have potential for application in ionizing-radiation detection devices due to their optimal optoelectronic properties. Yet, their mixed ionic-electronic conductivity produces instability and hysteretic artifacts hindering the long-term device operation. Herein, we report an electrical characterization of CsPbBr3 single crystals operating up to the time scale of hours. Our fast time-of-flight measurements reveal bulk mobilities of 13-26 cm2 V-1 s-1 with a negative voltage bias dependency. By means of a guard ring (GR) configuration, we separate bulk and surface mobilities showing significant qualitative and quantitative transport differences. Our experiments of current transients and impedance spectroscopy indicate the formation of several regimes of space-charge-limited current (SCLC) associated with mechanisms similar to the Poole-Frenkel ionized-trap-assisted transport. We show that the ionic-SCLC seems to be an operational mode in this lead halide perovskite, despite the fact that experiments can be designed where the contribution of mobile ions to transport is negligible.
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Affiliation(s)
- Osbel Almora
- Institute
of Advanced Materials (INAM), Universitat
Jaume I, 12006 Castelló, Spain
- Erlangen
Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Gebhard J. Matt
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Albert These
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
- Erlangen
Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Andrii Kanak
- Department
of General Chemistry and Chemistry of Materials, Yuriy Fedkovych Chernivtsi National University, 2, Kotsyubynsky St., 58012 Chernivtsi, Ukraine
| | - Ievgen Levchuk
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Shreetu Shrestha
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Andres Osvet
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Christoph J. Brabec
- Institute
of Materials for Electronics and Energy technologies (i-MEET), Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
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