Templated Self-Assembly and Local Doping of Molecules on Epitaxial Hexagonal Boron Nitride

Schulz, Fabian; Drost, Robert; Hämäläinen, Sampsa K.; Liljeroth, Peter

doi:10.1021/nn404840h

Cited by 96 publications

(162 citation statements)

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“…This gives rise to a fundamental difference in the electronic properties: While Gr is a zero-band-gap semiconductor, h-BN is an excellent insulator with a bandgap of about 5 eV [1]. Because of its inertness, flatness, structural perfection, and insulating character, cleaved bulk hexagonal boron nitride or monolayers of h-BN are now widely used as substrates for organic molecules [2,3], topological insulators [4], and graphene [5]. Hexagonal boron nitride is established as a key component in vertical van der Waals heterostructures [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Annealing of ion-irradiated hexagonal boron nitride on Ir(111)

et al. 2017

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Annealing of a monolayer of hexagonal boron nitride destroyed by Xe ion irradiation gives rise to rich structural phenomena investigated here through a combination of scanning tunneling microscopy, low-energy electron diffraction, x-ray photoelectron spectroscopy, and density functional theory calculations. We find selective pinning of vacancy clusters at a single specific location within the moiré formed by hexagonal boron nitride (h-BN) and the Ir substrate, crystalline Xe at room temperature of monolayer and bilayer thickness sealed inside h-BN blisters, standalone blisters only bound to the metal at temperatures where boron nitride on Ir (111) decomposes, and finally a pronounced threefold symmetry of all morphological features due to the preferential formation of boron-terminated zigzag edges that firmly bind to the substrate. The investigations give clear insight into the relevance of the substrate for the damage creation and annealing in a two-dimensional layer material.

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Section: Introductionmentioning

confidence: 99%

Annealing of ion-irradiated hexagonal boron nitride on Ir(111)

et al. 2017

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“…Another area of interest in h-BN are the so-called boron nitride nanomeshesepitaxial monolayers of h-BN grown on transition metal surfaces [4,5]. Various studies have been motivated by their ability to act as a template for bottom-up fabrication techniques, while simultaneously providing electronic decoupling from the metallic substrate [4,[6][7][8][9][10][11][12][13]. The term "nanomesh" highlights the peculiar structure of the h-BN monolayers: Due to the lattice mismatch with the underlying substrate, the atomic registry between the boron and nitrogen atoms and the metallic surface is periodically modulated, resulting in a moiré pattern formed by regions of stronger h-BN/metal and weaker h-BN/metal interaction.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial hexagonal boron nitride on Ir(111): A work function template

et al. 2014

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Hexagonal boron nitride (h-BN) is a prominent member in the growing family of two-dimensional materials with potential applications ranging from being an atomically smooth support for other two-dimensional materials to templating growth of molecular layers. We have studied the structure of monolayer h-BN grown by chemical vapor deposition on Ir(111) by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments and state-of-the-art density functional theory (DFT) calculations. The lattice mismatch between the h-BN and Ir (111) surface results in the formation of a moiré superstructure with a periodicity of ∼29Å and a corrugation of ∼0.4Å. By measuring the field emission resonances above the h-BN layer, we find a modulation of the work function within the moiré unit cell of ∼0.5 eV. DFT simulations for a 13-on-12 h-BN/Ir(111) unit cell confirm our experimental findings and allow us to relate the change in the work function to the subtle changes in the interaction between boron and nitrogen atoms and the underlying substrate atoms within the moiré unit cell. Hexagonal boron nitride on Ir(111) combines weak topographic corrugation with a strong work function modulation over the moiré unit cell. This makes h-BN/Ir(111) a potential substrate for electronically modulated thin film and heterosandwich structures.

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“…This feature, which can also be discerned in Figure 1a, closely resembles the highest occupied π molecular orbital (π-HOMO) level of a Pc ligand as seen in DFT calculations of an isolated molecule. [19] STM images of weakly interacting Pc molecules on thin insulators [14,34] and the decoupled top Pc ligand of a double decker Pc molecule [35][36][37] also exhibit this same electronic structure.…”

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confidence: 74%

“…[11,12] For example, it has been shown that molecules can become trapped within nanopores of hexagonal boron nitride grown on Ru (0001) because of dipolar interactions; [13,14] similar results have also been observed for nanopores on the surface of bulk SiC. [15] Physisorption of a molecule to a surface (i.e., van der Waals bonding) is often not strong enough to fix the molecule's position at room temperature, particularly on the surface of bulk metal crystals.…”

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confidence: 99%

Guided Molecular Assembly on a Locally Reactive 2D Material

et al. 2017

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occurs when 2D materials are placed on a substrate, such as when they are epitaxially grown upon a metallic surface. [11,12] For example, it has been shown that molecules can become trapped within nanopores of hexagonal boron nitride grown on Ru (0001) because of dipolar interactions; [13,14] similar results have also been observed for nanopores on the surface of bulk SiC. [15] Physisorption of a molecule to a surface (i.e., van der Waals bonding) is often not strong enough to fix the molecule's position at room temperature, particularly on the surface of bulk metal crystals. This is more readily accomplished by anchoring the mole cule to the surface through chemisorption of part of the molecule to the surface. [16][17][18] However, care must be taken to limit hybridization that can cause detrimental modifications of the molecule and its frontier orbitals, [19,20] especially on different surface reconstructions of bulk semiconductors like silicon. [15,17] It is therefore of interest to investigate the interface between molecules and more reactive 2D materials in an attempt to isolate individual molecules at room temperature while retaining their localized electronic states.With its mixed sp 2 -sp 3 character, silicene-the silicon analogue of graphene-has the potential to provide unique properties for molecular templating. This is particularly true because the structural and electronic properties of silicene are more susceptible to modification [21][22][23][24][25][26] once it is formed upon a surface, owing to its greater reactivity than graphene and the flexibility of The interactions between atomic or molecular adsorbates and the surfaces of 2D materials are of interest for applications ranging from catalysis [1] and molecular sensing [2] to molecular electronics and spintronics. [3][4][5] For the prototypical 2D material graphene, there are typically only weak van der Waals interactions between molecules and the surface. [6] This allows for the fabrication of functional self-assembled monolayers [6][7][8] that are reminiscent of the ordered supramolecular arrangements that can be formed on the surfaces of bulk (3D) materials. [9] However, isolating individual molecules is more challenging. [10] In contrast, new possibilities for templating emerge from nanostructuring that

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Templated Self-Assembly and Local Doping of Molecules on Epitaxial Hexagonal Boron Nitride

Cited by 96 publications

References 49 publications

Annealing of ion-irradiated hexagonal boron nitride on Ir(111)

Annealing of ion-irradiated hexagonal boron nitride on Ir(111)

Epitaxial hexagonal boron nitride on Ir(111): A work function template

Guided Molecular Assembly on a Locally Reactive 2D Material

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