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Picker J, Schaal M, Gan Z, Gruenewald M, Neumann C, George A, Otto F, Forker R, Fritz T, Turchanin A. Structural and electronic properties of MoS 2 and MoSe 2 monolayers grown by chemical vapor deposition on Au(111). NANOSCALE ADVANCES 2023; 6:92-101. [PMID: 38125607 PMCID: PMC10729873 DOI: 10.1039/d3na00475a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/24/2023] [Indexed: 12/23/2023]
Abstract
The exceptional electronic and photonic properties of the monolayers of transition metal dichalcogenides including the spin-orbit splitting of the valence and conduction bands at the K points of the Brillouin zone make them promising for novel applications in electronics, photonics and optoelectronics. Scalable growth of these materials and understanding of their interaction with the substrate is crucial for these applications. Here we report the growth of MoS2 and MoSe2 monolayers on Au(111) by chemical vapor deposition at ambient pressure as well as the analysis of their structural and electronic properties down to the atomic scale. To this aim, we apply ultrahigh vacuum surface sensitive techniques including scanning tunneling microscopy and spectroscopy, low-energy electron diffraction, X-ray and angle-resolved ultraviolet photoelectron spectroscopy in combination with Raman spectroscopy at ambient conditions. We demonstrate the growth of high-quality epitaxial single crystalline MoS2 and MoSe2 monolayers on Au(111) and show the impact of annealing on the monolayer/substrate interaction. Thus, as-grown and moderately annealed (<100 °C) MoSe2 monolayers are decoupled from the substrate by excess Se atoms, whereas annealing at higher temperatures (>250 °C) results in their strong coupling with the substrate caused by desorption of the excess Se. The MoS2 monolayers are strongly coupled to the substrate and the interaction remains almost unchanged even after annealing up to 450 °C.
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Affiliation(s)
- Julian Picker
- Institute of Physical Chemistry, Friedrich Schiller University Jena Lessingstraße 10 07743 Jena Germany
| | - Maximilian Schaal
- Institute of Solid State Physics, Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
| | - Ziyang Gan
- Institute of Physical Chemistry, Friedrich Schiller University Jena Lessingstraße 10 07743 Jena Germany
| | - Marco Gruenewald
- Institute of Solid State Physics, Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
| | - Christof Neumann
- Institute of Physical Chemistry, Friedrich Schiller University Jena Lessingstraße 10 07743 Jena Germany
| | - Antony George
- Institute of Physical Chemistry, Friedrich Schiller University Jena Lessingstraße 10 07743 Jena Germany
| | - Felix Otto
- Institute of Solid State Physics, Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
| | - Roman Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
| | - Torsten Fritz
- Institute of Solid State Physics, Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
| | - Andrey Turchanin
- Institute of Physical Chemistry, Friedrich Schiller University Jena Lessingstraße 10 07743 Jena Germany
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2
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Koch J, Ghosal C, Sologub S, Tegenkamp C. Morphology of Bi(110) quantum islands on epitaxial graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:065701. [PMID: 37871600 DOI: 10.1088/1361-648x/ad05fb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 10/23/2023] [Indexed: 10/25/2023]
Abstract
Proximitized 2D materials present exciting prospects for exploring new quantum properties, enabled by precise control of structures and interfaces through epitaxial methods. In this study, we investigated the structure of ultrathin coverages formed by depositing high-Z element bismuth (Bi) on monolayer graphene (MLG)/SiC(0001). By utilizing electron diffraction and scanning tunneling microscopy, ultrathin Bi nanostructures epitaxially grown on MLG were studied. Deposition at 300 K resulted in formation of needle-like Bi(110)-terminated islands elongated in the zig-zag direction and aligned at an angle of approximately 1.75∘with respect to the MLG armchair direction. By both strain and quantum size effects, the shape, the orientation and the thickness of the Bi(110) islands can be rationalized. Additionally, a minority phase of Bi(110) islands orthogonally aligned to the former ones were seen. The four sub-domains of this minority structure are attributed to the formation of mirror twin boundaries, resulting in two potential alignments of Bi(110) majority and minority domains with respect to each other, in addition to two possible alignments of the majority domain with respect to graphene. Notably, an annealing step at 410 K or lowering the deposition temperature, significantly increases the concentration of the Bi(110) minority domain. Our findings shed light on the structural control of proximitized 2D materials, showcasing the potential for manipulating 2D interfaces.
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Affiliation(s)
- Julian Koch
- Institut für Physik, Technische Universtät Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz, Germany
| | - Chitran Ghosal
- Institut für Physik, Technische Universtät Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz, Germany
| | - Sergii Sologub
- Institut für Physik, Technische Universtät Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz, Germany
- Institute of Physics, National Academy of Sciences of Ukraine, Nauki avenue 46, 03028 Kyiv, Ukraine
| | - Christoph Tegenkamp
- Institut für Physik, Technische Universtät Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz, Germany
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3
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Yamada T, Tawa T, Murase N, Kato HS. Formation and Structural Characterization of Two-dimensional Wetting Water Layer on Graphite (0001). J Chem Phys 2022; 157:074702. [DOI: 10.1063/5.0097760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Understanding the structure and wettability of monolayer water is essential for revealing the mechanisms of nucleation, growth, and chemical reactivity at interfaces. We have investigated the wetting layer formation of water (ice) on the graphite (0001) surface using a combination of low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). At around monolayer coverages, the LEED pattern showed a (2×2) periodicity, and the STM revealed a hydrogen-bonded hexagonal network. The lattice constant was about 9% larger than that for ice Ih/Ic crystals, and the packing density was 0.096 Å-2. These results indicate that an extended ice network is formed on graphite, different from that on metal surfaces. Graphite is hydrophobic under ambient conditions due to the airborne contaminant but is considered inherently hydrophilic for a clean surface. In this study, the hydrophilic nature of the clean surface has been investigated from a molecular viewpoint. The formation of a well-ordered commensurate monolayer supports that the interaction of water with graphite is not negligible so that a commensurate wetting layer is formed at the weak substrate-molecule interaction limit.
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Affiliation(s)
- Takashi Yamada
- Chemistry, Graduate School of Science, Osaka University Graduate School of Science Department of Chemistry, Japan
| | - Takenori Tawa
- Osaka University Graduate School of Science Department of Chemistry, Japan
| | - Natsumi Murase
- Osaka University Graduate School of Science Department of Chemistry, Japan
| | - Hiroyuki S Kato
- Osaka University Graduate School of Science Department of Chemistry, Japan
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4
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Li J, Chen M, Samad A, Dong H, Ray A, Zhang J, Jiang X, Schwingenschlögl U, Domke J, Chen C, Han Y, Fritz T, Ruoff RS, Tian B, Zhang X. Wafer-scale single-crystal monolayer graphene grown on sapphire substrate. NATURE MATERIALS 2022; 21:740-747. [PMID: 35058609 DOI: 10.1038/s41563-021-01174-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 11/23/2021] [Indexed: 05/03/2023]
Abstract
The growth of inch-scale high-quality graphene on insulating substrates is desirable for electronic and optoelectronic applications, but remains challenging due to the lack of metal catalysis. Here we demonstrate the wafer-scale synthesis of adlayer-free ultra-flat single-crystal monolayer graphene on sapphire substrates. We converted polycrystalline Cu foil placed on Al2O3(0001) into single-crystal Cu(111) film via annealing, and then achieved epitaxial growth of graphene at the interface between Cu(111) and Al2O3(0001) by multi-cycle plasma etching-assisted-chemical vapour deposition. Immersion in liquid nitrogen followed by rapid heating causes the Cu(111) film to bulge and peel off easily, while the graphene film remains on the sapphire substrate without degradation. Field-effect transistors fabricated on as-grown graphene exhibited good electronic transport properties with high carrier mobilities. This work breaks a bottleneck of synthesizing wafer-scale single-crystal monolayer graphene on insulating substrates and could contribute to next-generation graphene-based nanodevices.
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Affiliation(s)
- Junzhu Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, China
| | - Mingguang Chen
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Abdus Samad
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Haocong Dong
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, China
| | - Avijeet Ray
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Junwei Zhang
- School of Materials and Energy, Electron Microscopy Centre of Lanzhou University and Key Laboratory of Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, China
| | - Xiaochuan Jiang
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, China
- Department of Physics, Xiamen University, Xiamen, China
| | - Udo Schwingenschlögl
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Jari Domke
- Institute of Solid State Physics (IFK), Friedrich Schiller University Jena, Jena, Germany
| | - Cailing Chen
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Yu Han
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Torsten Fritz
- Institute of Solid State Physics (IFK), Friedrich Schiller University Jena, Jena, Germany
| | - Rodney S Ruoff
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan, Republic of Korea
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
- School of Chemical Engineering and Energy Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Bo Tian
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, China.
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
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5
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Simbrunner J, Domke J, Sojka F, Jeindl A, Otto F, Gruenewald M, Hofmann OT, Fritz T, Resel R, Forker R. Correlation between two- and three-dimensional crystallographic lattices for epitaxial analysis. II. Experimental results. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022; 78:272-282. [PMID: 35502718 PMCID: PMC9062826 DOI: 10.1107/s2053273322002170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 02/23/2022] [Indexed: 11/10/2022]
Abstract
Organic epitaxy is studied experimentally in terms of the correlation of the involved two- and three-dimensional crystallographic lattices. While the crystal structure of the polymorph phase can be studied in three dimensions conveniently by X-ray methods like grazing-incidence X-ray diffraction (GIXD), the first monolayer is only accessible by surface-sensitive methods that allow the determination of a two-dimensional lattice. Here, GIXD measurements with sample rotation are compared with distortion-corrected low-energy electron diffraction (LEED) experiments on conjugated molecules: 3,4;9,10-perylenetetracarboxylic dianhydride (PTCDA), 6,13-pentacenequinone (P2O), 1,2;8,9-dibenzopentacene (trans-DBPen) and dicyanovinyl-quaterthiophene (DCV4T-Et2) grown by physical vapor deposition on Ag(111) and Cu(111) single crystals. For these molecular crystals, which exhibit different crystallographic lattices and crystal orientations as well as epitaxial properties, the geometric parameters of the three-dimensional lattice are compared with the corresponding geometry of the first monolayer. A comparison of the monolayer lattice from LEED investigations with the multilayer lattices determined by rotated GIXD experiments reveals a correlation between the first monolayer and the epitaxial growth of three-dimensional crystals together with lattice distortions and re-alignment of molecules. The selected examples show three possible scenarios of crystal growth on top of an ordered monolayer: (i) growth of a single polymorph, (ii) growth of three different polymorphs; in both cases the first monolayer serves as template. In the third case (iii) strong lattice distortion and distinct molecular re-alignments from the monolayer to epitaxially grown crystals are observed. This is the second part of our work concerning the correlation between two- and three-dimensional crystallographic lattices for epitaxial analysis. In the first part, the theoretical basis has been derived which provides a mathematical relationship between the six lattice parameters of the three-dimensional case and the three parameters obtained for the two-dimensional surface unit cell, together with their orientation to the single-crystalline substrate. In this work, a combined experimental approach of GIXD and LEED is introduced which can be used to investigate the effect of the epitaxial monolayer on the structural properties of molecular crystals grown on top.
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6
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Simbrunner J, Domke J, Forker R, Resel R, Fritz T. Correlation between two- and three-dimensional crystallographic lattices for epitaxial analysis. I. Theory. Acta Crystallogr A Found Adv 2022; 78:262-271. [PMID: 35502717 PMCID: PMC9062828 DOI: 10.1107/s2053273322002182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 02/23/2022] [Indexed: 11/24/2022] Open
Abstract
A general formalism to determine the surface unit cell of a three-dimensional crystallographic lattice is presented. The epitaxial growth of molecular crystals at single-crystalline surfaces is often strongly related to the first monolayer at the substrate surface. The present work presents a theoretical approach to compare three-dimensional lattices of epitaxially grown crystals with two-dimensional lattices of the molecules formed within the first monolayer. Real-space and reciprocal-space representations are considered. Depending on the crystallographic orientation relative to the substrate surface, proper linear combinations of the lattice vectors of the three-dimensional unit cell result in a rhomboid in the xy plane, representing a two-dimensional projection. Mathematical expressions are derived which provide a relationship between the six lattice parameters of the three-dimensional case and the three parameters obtained for the two-dimensional surface unit cell. It is found that rotational symmetries of the monolayers are reflected by the epitaxial order. Positive and negative orientations of the crystallographic contact planes are correlated with the mirror symmetry of the surface unit cells, and the corresponding mathematical expressions are derived. The method is exemplarily applied to data obtained in previous grazing-incidence X-ray diffraction (GIXD) measurements with sample rotation on thin films of the conjugated molecules 3,4;9,10-perylenetetracarboxylic dianhydride (PTCDA), 6,13-pentacenequinone (P2O), 1,2;8,9-dibenzopentacene (trans-DBPen) and dicyanovinyl-quaterthiophene (DCV4T-Et2) grown by physical vapor deposition on Ag(111) and Cu(111) single crystals. This work introduces the possibility to study three-dimensional crystal growth nucleated by an ordered monolayer by combining two different experimental techniques, GIXD and low-energy electron diffraction, which has been implemented in the second part of this work.
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7
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Hayashida K, Tsuda Y, Yamada T, Yoshigoe A, Okada M. Revisit of XPS Studies of Supersonic O 2 Molecular Adsorption on Cu(111): Copper Oxides. ACS OMEGA 2021; 6:26814-26820. [PMID: 34661036 PMCID: PMC8515815 DOI: 10.1021/acsomega.1c04663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 09/20/2021] [Indexed: 06/08/2023]
Abstract
We report the X-ray photoemission spectroscopy (XPS) characterization of the bulk Cu2O(111) surface and "8" and "29" oxide structures on Cu(111) prepared using a 0.5 eV O2 supersonic molecular beam. We propose a new structural model for the "8" oxide structure and also confirm the previously proposed model for the "29" oxide structure on Cu(111), based on the O 1s XPS spectra. The detection angle dependence of the O 1s spectra supports that the nanopyramidal model is more preferable for the (√3 × √3)R30° Cu2O(111). We also report electronic excitations that O 1s electrons suffer.
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Affiliation(s)
- Koki Hayashida
- Department
of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yasutaka Tsuda
- Materials
Sciences Research Center, Japan Atomic Energy
Agency, Sayo-gun, Hyogo 679-5148, Japan
| | - Takashi Yamada
- Department
of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Akitaka Yoshigoe
- Materials
Sciences Research Center, Japan Atomic Energy
Agency, Sayo-gun, Hyogo 679-5148, Japan
| | - Michio Okada
- Department
of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- Institute
for Radiation Sciences, Osaka University, Toyonaka, Osaka 560-0043, Japan
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8
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Schaal M, Picker J, Otto F, Gruenewald M, Forker R, Fritz T. An alternative route towards the fabrication of 2D blue phosphorene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:485002. [PMID: 34399408 DOI: 10.1088/1361-648x/ac1dde] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Blue phosphorene (BlueP) is a novel two-dimensional material that shares properties with black phosphorene and is potentially even more interesting for opto-electronic applications because of its layer dependent wide band gap of ≈ 2 to 3 eV and superior charge carrier mobility. It was first fabricated on Au(111), where, however, a network consisting of BlueP subunits and Au-linker atoms is formed. The physical properties of such an arrangement strongly differ from a freestanding BlueP monolayer. Here, we report on the growth of epitaxial BlueP on the Au(100) surface, which is an interesting alternative when aiming at quasi-freestanding BlueP domains. We find two different phosphorus phases by means of scanning tunneling microscopy and distortion-corrected low-energy electron diffraction. In the low coverage regime, we observe a commensurate (2 × 2) phase, whereas for higher coverage, a nearly hexagonal structure is formed. For the latter, the lattice parameters measured via atomically resolved scanning tunneling hydrogen microscopy closely resemble those of freestanding BlueP, and the typical height modulation of the phosphorus atoms is verified in our layers by means of x-ray photoelectron diffraction. We further analyze the chemical and electronic properties of these films by means of x-ray and (angle resolved) ultraviolet photoelectron spectroscopy.
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Affiliation(s)
- M Schaal
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - J Picker
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Lessingstraße 10, 07743 Jena, Germany
| | - F Otto
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - M Gruenewald
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - R Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - T Fritz
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
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9
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Nazzari D, Genser J, Ritter V, Bethge O, Bertagnolli E, Ramer G, Lendl B, Watanabe K, Taniguchi T, Rurali R, Kolíbal M, Lugstein A. Highly Biaxially Strained Silicene on Au(111). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:9973-9980. [PMID: 34055129 PMCID: PMC8154839 DOI: 10.1021/acs.jpcc.0c11033] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/22/2021] [Indexed: 05/20/2023]
Abstract
Many of graphene's remarkable properties arise from its linear dispersion of the electronic states, forming a Dirac cone at the K points of the Brillouin zone. Silicene, the 2D allotrope of silicon, is also predicted to show a similar electronic band structure, with the addition of a tunable bandgap, induced by spin-orbit coupling. Because of these outstanding electronic properties, silicene is considered as a promising building block for next-generation electronic devices. Recently, it has been shown that silicene grown on Au(111) still possesses a Dirac cone, despite the interaction with the substrate. Here, to fully characterize the structure of this 2D material, we investigate the vibrational spectrum of a monolayer silicene grown on Au(111) by polarized Raman spectroscopy. To enable a detailed ex situ investigation, we passivated the silicene on Au(111) by encapsulating it under few layers hBN or graphene flakes. The observed spectrum is characterized by vibrational modes that are strongly red-shifted with respect to the ones expected for freestanding silicene. By comparing low-energy electron diffraction (LEED) patterns and Raman results with first-principles calculations, we show that the vibrational modes indicate a highly (>7%) biaxially strained silicene phase.
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Affiliation(s)
- Daniele Nazzari
- Institute
of Solid State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Jakob Genser
- Institute
of Solid State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Viktoria Ritter
- Institute
of Solid State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Ole Bethge
- Infineon
Technologies Austria AG, Siemensstraße 2, 9500 Villach, Austria
| | - Emmerich Bertagnolli
- Institute
of Solid State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Georg Ramer
- Institute
of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Bernhard Lendl
- Institute
of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Riccardo Rurali
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain
| | - Miroslav Kolíbal
- Institute
of Physical Engineering, Brno University
of Technology, Technická 2, 616 69 Brno, Czech Republic
- CEITEC
BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech
Republic
| | - Alois Lugstein
- Institute
of Solid State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
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10
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Jeindl A, Domke J, Hörmann L, Sojka F, Forker R, Fritz T, Hofmann OT. Nonintuitive Surface Self-Assembly of Functionalized Molecules on Ag(111). ACS NANO 2021; 15:6723-6734. [PMID: 33728893 PMCID: PMC8155339 DOI: 10.1021/acsnano.0c10065] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/10/2021] [Indexed: 05/22/2023]
Abstract
The fabrication of nanomaterials involves self-ordering processes of functional molecules on inorganic surfaces. To obtain specific molecular arrangements, a common strategy is to equip molecules with functional groups. However, focusing on the functional groups alone does not provide a comprehensive picture. Especially at interfaces, processes that govern self-ordering are complex and involve various physical and chemical effects, often leading to unexpected structures, as we showcase here on the example of a homologous series of quinones on Ag(111). Naively, one could expect that such quinones, which all bear the same functionalization, form similar motifs. In salient contrast, our joint theoretical and experimental study shows that profoundly different structures are formed. Using a machine-learning-based structure search algorithm, we find that this is due to a shift of the balance of three antagonizing driving forces: adsorbate-substrate interactions governing adsorption sites, adsorbate-adsorbate interactions favoring close packing, and steric hindrance inhibiting certain otherwise energetically beneficial molecular arrangements. The theoretical structures show excellent agreement with our experimental characterizations of the organic/inorganic interfaces, both for the unit cell sizes and the orientations of the molecules within. The nonintuitive interplay of similarly important interaction mechanisms will continue to be a challenging aspect for the design of functional interfaces. With a detailed examination of all driving forces, we are, however, still able to devise a design principle for self-assembly of functionalized molecules.
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Affiliation(s)
- Andreas Jeindl
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Jari Domke
- Institute
for Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Lukas Hörmann
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Falko Sojka
- Institute
for Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Roman Forker
- Institute
for Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Torsten Fritz
- Institute
for Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Oliver T. Hofmann
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
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11
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Bocquet FC, Lin YR, Franke M, Samiseresht N, Parhizkar S, Soubatch S, Lee TL, Kumpf C, Tautz FS. Surfactant-Mediated Epitaxial Growth of Single-Layer Graphene in an Unconventional Orientation on SiC. PHYSICAL REVIEW LETTERS 2020; 125:106102. [PMID: 32955317 DOI: 10.1103/physrevlett.125.106102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 01/08/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
We report the use of a surfactant molecule during the epitaxy of graphene on SiC(0001) that leads to the growth in an unconventional orientation, namely R0° rotation with respect to the SiC lattice. It yields a very high-quality single-layer graphene with a uniform orientation with respect to the substrate, on the wafer scale. We find an increased quality and homogeneity compared to the approach based on the use of a preoriented template to induce the unconventional orientation. Using spot profile analysis low-energy electron diffraction, angle-resolved photoelectron spectroscopy, and the normal incidence x-ray standing wave technique, we assess the crystalline quality and coverage of the graphene layer. Combined with the presence of a covalently bound graphene layer in the conventional orientation underneath, our surfactant-mediated growth offers an ideal platform to prepare epitaxial twisted bilayer graphene via intercalation.
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Affiliation(s)
- F C Bocquet
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Y-R Lin
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
| | - M Franke
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
| | - N Samiseresht
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
| | - S Parhizkar
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - S Soubatch
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - T-L Lee
- Diamond Light Source, Ltd., Didcot OX110DE, Oxfordshire, United Kingdom
| | - C Kumpf
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
| | - F S Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany
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12
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Schaal M, Aihara T, Gruenewald M, Otto F, Domke J, Forker R, Yoshida H, Fritz T. Hybridization vs decoupling: influence of an h-BN interlayer on the physical properties of a lander-type molecule on Ni(111). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1168-1177. [PMID: 32821641 PMCID: PMC7418096 DOI: 10.3762/bjnano.11.101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/08/2020] [Indexed: 05/20/2023]
Abstract
2D materials such as hexagonal boron nitride (h-BN) are widely used to decouple organic molecules from metal substrates. Nevertheless, there are also indications in the literature for a significant hybridization, which results in a perturbation of the intrinsic molecular properties. In this work we study the electronic and optical properties as well as the lateral structure of tetraphenyldibenzoperiflanthene (DBP) on Ni(111) with and without an atomically thin h-BN interlayer to investigate its possible decoupling effect. To this end, we use in situ differential reflectance spectroscopy as an established method to distinguish between hybridized and decoupled molecules. By inserting an h-BN interlayer we fabricate a buried interface and show that the DBP molecules are well decoupled from the Ni(111) surface. Furthermore, a highly ordered DBP monolayer is obtained on h-BN/Ni(111) by depositing the molecules at a substrate temperature of 170 °C. The structural results are obtained by quantitative low-energy electron diffraction and low-temperature scanning tunneling microscopy. Finally, the investigation of the valence band structure by ultraviolet photoelectron spectroscopy shows that the low work function of h-BN/Ni(111) further decreases after the DBP deposition. For this reason, the h-BN-passivated Ni(111) surface may serve as potential n-type contact for future molecular electronic devices.
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Affiliation(s)
- Maximilian Schaal
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Takumi Aihara
- Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Marco Gruenewald
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Felix Otto
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Jari Domke
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Roman Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Hiroyuki Yoshida
- Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Torsten Fritz
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany
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13
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Yamada T, Ito N, Kawakita N, Kato HS, Munakata T. Formation and regulation of unoccupied hybridized band with image potential states at perylene/graphite interface. J Chem Phys 2019; 151:224703. [DOI: 10.1063/1.5126373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Takashi Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Natsumi Ito
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Noriaki Kawakita
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Hiroyuki S. Kato
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Toshiaki Munakata
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
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14
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Forker R, Gruenewald M, Sojka F, Peuker J, Mueller P, Zwick C, Huempfner T, Meissner M, Fritz T. Fraternal twins: distinction between PbPc and SnPc by their switching behaviour in a scanning tunnelling microscope. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:134004. [PMID: 30729922 DOI: 10.1088/1361-648x/aafeae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In this contribution, we compare the optical absorbance behaviour and the structural properties of lead(II)-phthalocyanine (PbPc) and tin(II)-phthalocyanine (SnPc) thin films. To this end, we employ a Ag(1 1 1) substrate terminated with a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride constituting an internal interface whose main effect is an electronic decoupling of the phthalocyanine adlayer from the metal surface. As deduced from low-energy electron diffraction and scanning tunnelling microscopy (STM) measurements, the epitaxial relations and unit cell compositions of the prevailing PbPc monolayer and multilayer domains are confusingly similar to those of SnPc on PTCDA/Ag(1 1 1). However, SnPc and PbPc can be readily distinguished by their STM-induced switching behaviours: while the former is capable of reversible configurational changes, no effect on the latter could be achieved by us under comparable conditions. This corroborates earlier theoretical predictions and even renders the chemical identification of individual shuttlecock-shaped metal-phthalocyanines feasible.
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Affiliation(s)
- Roman Forker
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
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15
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Mehler A, Kirchhuebel T, Néel N, Sojka F, Forker R, Fritz T, Kröger J. Ordered Superstructures of a Molecular Electron Donor on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6978-6984. [PMID: 28602078 DOI: 10.1021/acs.langmuir.7b00306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The molecular donor tetraphenyldibenzoperiflanthene (DBP) forms coverage-dependent superstructures on Au(111). At submonolayer coverage, the molecules align parallel to each other. They arrange in row-like structures, which exhibit a nearly rectangular primitive unit cell. By contrast, the molecular monolayer is characterized by a herringbone-type DBP arrangement spanned by an almost square unit cell containing two molecules. Both superstructures occur simultaneously in a narrow coverage range close to completion of the molecular monolayer. The adsorbate-substrate interaction is similar to other physisorbed molecular films on Au(111), but differs for the two adsorption phases as inferred from the different modification of the Au(111) surface reconstruction. Structural properties were consistently probed in real and reciprocal space by scanning tunneling microscopy and low-energy electron diffraction, respectively.
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Affiliation(s)
- A Mehler
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - T Kirchhuebel
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , D-07743 Jena, Germany
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - F Sojka
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , D-07743 Jena, Germany
| | - R Forker
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , D-07743 Jena, Germany
| | - T Fritz
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , D-07743 Jena, Germany
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
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16
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Forker R, Meissner M, Fritz T. Classification of epitaxy in reciprocal and real space: rigid versus flexible lattices. SOFT MATTER 2017; 13:1748-1758. [PMID: 28210723 DOI: 10.1039/c6sm02688e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Early investigations of epitaxy focused on inorganic adsorbates consisting of atoms or few-atom molecules, where commensurate registries are predominantly encountered. Expanding such studies to larger (organic) molecules has revealed hitherto unknown types of epitaxy with coherence between adlayer and substrate lattices in just one direction. Here we review recent contributions to the fundamental understanding and modeling of epitaxy. By sorting the ideas brought forward in the literature and amending some basic algebraic considerations a universal scheme for the classification of lattice epitaxy is presented. Ultimately, the occurrence of the different types of epitaxy is made plausible by easy-to-grasp energetic arguments.
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Affiliation(s)
- Roman Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany.
| | - Matthias Meissner
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany.
| | - Torsten Fritz
- Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany.
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17
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Huempfner T, Hafermann M, Udhardt C, Otto F, Forker R, Fritz T. Insight into the unit cell: Structure of picene thin films on Ag(100) revealed with complementary methods. J Chem Phys 2016; 145:174706. [DOI: 10.1063/1.4966200] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Tobias Huempfner
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Martin Hafermann
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Christian Udhardt
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Felix Otto
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Roman Forker
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | - Torsten Fritz
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
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18
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Meissner M, Sojka F, Matthes L, Bechstedt F, Feng X, Müllen K, Mannsfeld SCB, Forker R, Fritz T. Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves. ACS NANO 2016; 10:6474-83. [PMID: 27014920 PMCID: PMC4963923 DOI: 10.1021/acsnano.6b00935] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 03/25/2016] [Indexed: 05/27/2023]
Abstract
The epitaxy of many organic films on inorganic substrates can be classified within the framework of rigid lattices which helps to understand the origin of energy gain driving the epitaxy of the films. Yet, there are adsorbate-substrate combinations with distinct mutual orientations for which this classification fails and epitaxy cannot be explained within a rigid lattice concept. It has been proposed that tiny shifts in atomic positions away from ideal lattice points, so-called static distortion waves (SDWs), are responsible for the observed orientational epitaxy in such cases. Using low-energy electron diffraction and scanning tunneling microscopy, we provide direct experimental evidence for SDWs in organic adsorbate films, namely hexa-peri-hexabenzocoronene on graphite. They manifest as wave-like sub-Ångström molecular displacements away from an ideal adsorbate lattice which is incommensurate with graphite. By means of a density-functional-theory based model, we show that, due to the flexibility in the adsorbate layer, molecule-substrate energy is gained by straining the intermolecular bonds and that the resulting total energy is minimal for the observed domain orientation, constituting the orientational epitaxy. While structural relaxation at an interface is a common assumption, the combination of the precise determination of the incommensurate epitaxial relation, the direct observation of SDWs in real space, and their identification as the sole source of epitaxial energy gain constitutes a comprehensive proof of this effect.
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Affiliation(s)
- Matthias Meissner
- Institute
of Solid State Physics, Friedrich Schiller
University, Helmholtzweg
5, 07743 Jena, Germany
| | - Falko Sojka
- Institute
of Solid State Physics, Friedrich Schiller
University, Helmholtzweg
5, 07743 Jena, Germany
| | - Lars Matthes
- Institute
of Condensed Matter Theory and Solid State Optics, Friedrich Schiller University, Fröbelstieg 1, 07743 Jena, Germany
| | - Friedhelm Bechstedt
- Institute
of Condensed Matter Theory and Solid State Optics, Friedrich Schiller University, Fröbelstieg 1, 07743 Jena, Germany
| | - Xinliang Feng
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Klaus Müllen
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Stefan C. B. Mannsfeld
- Center
for Advancing Electronics, University of
Technology Dresden, Würzburger
Strasse 46, 01187 Dresden, Germany
| | - Roman Forker
- Institute
of Solid State Physics, Friedrich Schiller
University, Helmholtzweg
5, 07743 Jena, Germany
| | - Torsten Fritz
- Institute
of Solid State Physics, Friedrich Schiller
University, Helmholtzweg
5, 07743 Jena, Germany
- Graduate
School of Science and Institute for Academic Initiatives, Department
of Chemistry, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
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19
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Kirchhuebel T, Gruenewald M, Sojka F, Kera S, Bussolotti F, Ueba T, Ueno N, Rouillé G, Forker R, Fritz T. Self-Assembly of Tetraphenyldibenzoperiflanthene (DBP) Films on Ag(111) in the Monolayer Regime. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1981-7. [PMID: 26844381 DOI: 10.1021/acs.langmuir.5b04069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Tetraphenyldibenzoperiflanthene (DBP) is a promising candidate as a component of highly efficient organic photovoltaic cells and organic light-emitting diodes. The structural properties of thin films of this particular lander-type molecule on Ag(111) were investigated by complementary techniques. Highly ordered structures were obtained, and their mutual alignment was characterized by means of low-energy electron diffraction (LEED). Scanning tunneling microscopy (STM) images reveal two slightly different arrangements within the first monolayer (ML), both describable as specific herringbone patterns with two molecules per unit cell whose dibenzoperiflanthene framework is parallel to the surface. In contrast, single DBP molecules in the second ML were imaged with much higher intramolecular resolution, resembling the shape of the frontier orbitals in the gas phase as calculated by means of density functional theory (DFT). Further deposition leads to the growth of highly ordered bilayer islands on top of the first ML with identical unit cell dimensions and orientation but slightly inclined molecules. This suggests that the first ML acts as a template for the epitaxial growth of further layers. Simultaneously, a significant number of second-layer molecules mainly located at step edges or scattered over narrow terraces do not form highly ordered aggregates.
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Affiliation(s)
- Tino Kirchhuebel
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
| | - Marco Gruenewald
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
| | - Falko Sojka
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
| | - Satoshi Kera
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585, Japan
- SOKENDAI, The Graduate University for Advanced Studies , Okazaki 444-8585, Japan
- Graduate School of Advanced Integration Science, Chiba University , Chiba 263-8522, Japan
| | - Fabio Bussolotti
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585, Japan
| | - Takahiro Ueba
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585, Japan
- SOKENDAI, The Graduate University for Advanced Studies , Okazaki 444-8585, Japan
| | - Nobuo Ueno
- Graduate School of Advanced Integration Science, Chiba University , Chiba 263-8522, Japan
| | - Gaël Rouillé
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy, Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 3, 07743 Jena, Germany
| | - Roman Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
| | - Torsten Fritz
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
- Department of Chemistry, Graduate School of Science and Institute for Academic Initiatives, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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20
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Zwick C, Baby A, Gruenewald M, Verwüster E, Hofmann OT, Forker R, Fratesi G, Brivio GP, Zojer E, Fritz T. Complex Stoichiometry-Dependent Reordering of 3,4,9,10-Perylenetetracarboxylic Dianhydride on Ag(111) upon K Intercalation. ACS NANO 2016; 10:2365-74. [PMID: 26718635 PMCID: PMC4768340 DOI: 10.1021/acsnano.5b07145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Alkali metal atoms are frequently used for simple yet efficient n-type doping of organic semiconductors and as an ingredient of the recently discovered polycyclic aromatic hydrocarbon superconductors. However, the incorporation of dopants from the gas phase into molecular crystal structures needs to be controlled and well understood in order to optimize the electronic properties (charge carrier density and mobility) of the target material. Here, we report that potassium intercalation into the pristine 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) monolayer domains on a Ag(111) substrate induces distinct stoichiometry-dependent structural reordering processes, resulting in highly ordered and large KxPTCDA domains. The emerging structures are analyzed by low-temperature scanning tunneling microscopy, scanning tunneling hydrogen microscopy (ST[H]M), and low-energy electron diffraction as a function of the stoichiometry. The analysis of the measurements is corroborated by density functional theory calculations. These turn out to be essential for a correct interpretation of the experimental ST[H]M data. The epitaxy types for all intercalated stages are determined as point-on-line. The K atoms adsorb in the vicinity of the oxygen atoms of the PTCDA molecules, and their positions are determined with sub-Ångström precision. This is a crucial prerequisite for the prospective assessment of the electronic properties of such composite films, as they depend rather sensitively on the mutual alignment between donor atoms and acceptor molecules. Our results demonstrate that only the combination of experimental and theoretical approaches allows for an unambiguous explanation of the pronounced reordering of KxPTCDA/Ag(111) upon changing the K content.
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Affiliation(s)
- Christian Zwick
- Institute
of Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg
5, 07743 Jena, Germany
| | - Anu Baby
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
- Department
of Materials Science, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
| | - Marco Gruenewald
- Institute
of Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg
5, 07743 Jena, Germany
| | - Elisabeth Verwüster
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Oliver T. Hofmann
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Roman Forker
- Institute
of Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg
5, 07743 Jena, Germany
| | - Guido Fratesi
- Department
of Materials Science, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
- Dipartimento
di Fisica, Università degli Studi
di Milano, Via Celoria
16, 20133 Milano, Italy
| | - Gian Paolo Brivio
- Department
of Materials Science, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
| | - Egbert Zojer
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Torsten Fritz
- Institute
of Solid State Physics, Friedrich Schiller
University Jena, Helmholtzweg
5, 07743 Jena, Germany
- Graduate
School of Science and Institute for Academic Initiatives, Department
of Chemistry, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Osaka, Japan
- E-mail:
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21
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Forker R, Peuker J, Meissner M, Sojka F, Ueba T, Yamada T, Kato HS, Munakata T, Fritz T. The complex polymorphism and thermodynamic behavior of a seemingly simple system: naphthalene on Cu(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14163-14170. [PMID: 25361739 DOI: 10.1021/la503146w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Naphthalene, C10H8, is a polycyclic aromatic hydrocarbon (PAH) consisting of two fused benzene rings. From previous studies, it is known to form three different commensurate structures in thin epitaxial films on Cu(111), depending on the preparation conditions. One of these structures even exhibits a chiral motif of molecular rotations within the unit cell. In an attempt to elucidate this polymorphism, we performed in situ low-energy electron diffraction (LEED) as a function of temperature and surface coverage, revealing an unexpected and extraordinarily complex structural and thermodynamic behavior. We present experimental evidence for a phase transition from a two-dimensional gas to a highly ordered molecular solid via an intermediate metastable phase with moderate order (extending over a few lattice constants only) which undergoes a reversible orientational shift upon temperature variation. At monolayer coverage and above, we find that two different point-on-line (POL) coincident epitaxial relations constitute the dominant structures. This is remarkable because, so far, POL structures of naphthalene on Cu(111) and other substrates have either not been recognized or not obtained under the respective experimental conditions. Our results are corroborated by the analysis of characteristic moiré patterns observed in scanning tunneling microscopy (STM), indicative of a noncommensurate epitaxial registry.
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Affiliation(s)
- Roman Forker
- Institute of Solid State Physics, Friedrich Schiller University Jena , Helmholtzweg 5, 07743 Jena, Germany
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22
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Sojka F, Meissner M, Zwick C, Forker R, Vyshnepolsky M, Klein C, Horn-von Hoegen M, Fritz T. To tilt or not to tilt: correction of the distortion caused by inclined sample surfaces in low-energy electron diffraction. Ultramicroscopy 2013; 133:35-40. [PMID: 23770540 DOI: 10.1016/j.ultramic.2013.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/08/2013] [Accepted: 04/21/2013] [Indexed: 10/26/2022]
Abstract
Low-energy electron diffraction (LEED) is a widely employed technique for the structural characterization of crystalline surfaces and epitaxial adsorbates. For technical reasons the accessible reciprocal space is limited at a given primary electron energy E. This limitation may be overcome by sweeping E to observe higher diffraction orders decisively enhancing the quantitative examination. Yet, in many cases, such as molecular films with rather large unit cells, the adsorbate reflexes become less pronounced at energies high enough to observe substrate reflexes. One possibility to overcome this problem is an intentional inclination of the sample surface during the measurement at the expense of the quantitative interpretability of then severely distorted diffraction patterns. Here, we introduce a correction method for the axially symmetric distortion in LEED images of tilted samples. We provide experimental confirmation for micro-channel plate LEED and spot-profile analysis LEED instruments using the (7×7) reconstructed surface of a Si(111) single crystal as a reference sample. Finally, we demonstrate that the correction of this distortion considerably improves the quantitative analysis of diffraction patterns of adsorbates since substrate and adsorbate reflexes can be evaluated simultaneously. As an illustrative example we have chosen an epitaxial monolayer of 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111) that is known to form a commensurate superstructure.
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Affiliation(s)
- Falko Sojka
- Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena, Germany.
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