Epitaxial Growth of a Single-Domain Hexagonal Boron Nitride Monolayer

Orlando, Fabrizio; Lacovig, Paolo; Omiciuolo, Luca; Apostol, Nicoleta G.; Larciprete, R.; Baraldi, Alessandro; Lizzit, Silvano

doi:10.1021/nn5058968

Cited by 67 publications

(79 citation statements)

References 45 publications

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“…2(f). Note that the existence of mirror domains does not necessarily imply an equal distribution of domain types and even single domain orientations can be achieved in similar systems, depending on the growth conditions [28]. Based on the observed circular dichroism here, we conclude that the domain distribution is not equal in the present case.…”

Section: Diffmentioning

confidence: 56%

Spin and valley control of free carriers in single-layer WS2

et al. 2017

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The semiconducting single-layer transition metal dichalcogenides have been identified as ideal materials for accessing and manipulating spin-and valley-quantum numbers due to a set of favorable optical selection rules in these materials. Here, we apply time-and angle-resolved photoemission spectroscopy to directly probe optically excited free carriers in the electronic band structure of a high quality single layer of WS2. We observe that the optically generated free hole density in a single valley can be increased by a factor of 2 using a circularly polarized optical excitation. Moreover, we find that by varying the photon energy of the excitation we can tune the free carrier density in a given spin-split state around the valence band maximum of the material. The control of the photon energy and polarization of the excitation thus permits us to selectively excite free electron-hole pairs with a given spin and within a single valley.In two-dimensional (2D) materials, control of the spinand valley-degrees of freedom has been suggested as a new type of tuning knob for carrier dynamics [1]. Singlelayer (SL) transition metal dichalcogenides (TMDCs) such as SL MoS 2 and WS 2 are particularly promising candidates for new spin-and valley-tronic device paradigms, owing to the broken inversion symmetry of their crystal lattices, a strong spin-orbit coupling and a direct band gap at theK andK ′ valleys in the electronic structure of the materials [2-4]. These properties have been indirectly verified in SL TMDCs through selective excitation of bound electron-hole pairs with circularly polarized light, leading to the observation of valley polarized excitons [5][6][7][8], which could be coherently manipulated [9]. Device measurements have shown indications of spin-and valley-coupled photocurrents [10] and Hall effects [11,12]. Direct measurements of the electronic structure and associated quasiparticles have been carried out for the bulk TMDC material WSe 2 using photoemission spectroscopies with spin [13] and time resolution [14]. Such measurements can, to some degree, even give information about the situation in a single layer, due to the surface sensitivity of photoemission spectroscopy. However, there is a need for experimental evidence and quantification of these properties for free carriers in the electronic structure of actual SL TMDCs, which are truly non-inversion symmetric materials.Time-and angle-resolved photoemission spectroscopy (TR-ARPES) is a powerful experimental approach for detecting optically excited free carriers with time-, energyand momentum-resolution with extremely high sensitivity towards 2D materials [15,16]. In this technique, a pump pulse with tuneable photon energy and polarization optically excites the material in question. The excited state is then probed by ARPES with an ultraviolet pulse, produced via high harmonic generation (HHG), which can provide sufficiently high photon energies to reach theK valleys at the corner of the SL TMDC's Brillouin zone (BZ). Since the two pulses are time-delaye...

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Section: Diffmentioning

confidence: 56%

Spin and valley control of free carriers in single-layer WS2

et al. 2017

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“…Moreover, Auwärter et al revealed that the ratio of R‐0 and R‐60 structures on Ni (111) could be modulated by pretreating the Ni substrates, but the deep mechanism is unclear . Besides, through changing the precursor dosing manner, h‐BN of unique orientation can be grown on Ir (111) substrate . Only R‐60 h‐BN domains grow on Ir (111) by dosing borazine at low temperature and subsequent high temperature annealing, but R‐60 and R‐0 domains coexist if borazine is dosed directly at high‐temperature .…”

Section: Synthesis Properties and Applications Of Two Dimensional H‐bnmentioning

confidence: 99%

“…Besides, through changing the precursor dosing manner, h‐BN of unique orientation can be grown on Ir (111) substrate . Only R‐60 h‐BN domains grow on Ir (111) by dosing borazine at low temperature and subsequent high temperature annealing, but R‐60 and R‐0 domains coexist if borazine is dosed directly at high‐temperature . The R‐60 structure is also commonly found on Rh (111) and Ru (0001), where h‐BN monolayers are bonded on these surfaces much more strongly .…”

Section: Synthesis Properties and Applications Of Two Dimensional H‐bnmentioning

confidence: 99%

Boron Nitride Nanostructures: Fabrication, Functionalization and Applications

Yin

Yang

et al. 2016

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162

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Boron nitride (BN) structures are featured by their excellent thermal and chemical stability and unique electronic and optical properties. However, the lack of controlled synthesis of quality samples and the electrically insulating property largely prevent realizing the full potential of BN nanostructures. A comprehensive overview of the current status of the synthesis of two-dimensional hexagonal BN sheets, three dimensional porous hexagonal BN materials and BN-involved heterostructures is provided, highlighting the advantages of different synthetic methods. In addition, structural characterization, functionalizations and prospective applications of hexagonal BN sheets are intensively discussed. One-dimensional BN nanoribbons and nanotubes are then discussed in terms of structure, fabrication and functionality. In particular, the existing routes in pursuit of tunable electronic and magnetic properties in various BN structures are surveyed, calling upon synergetic experimental and theoretical efforts to address the challenges for pioneering the applications of BN into functional devices. Finally, the progress in BN superstructures and novel B/N nanostructures is also briefly introduced.

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“…Besides exfoliation, chemical vapor deposition on catalytically active metals is a way to prepare well-defined monolayers [13]. Examples are epitaxial h-BN layers on Rh(111) [14][15][16], Ru(0001) [17][18][19], Pt(111) [20], and Ir(111) [21][22][23][24][25][26][27].…”

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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Epitaxial Growth of a Single-Domain Hexagonal Boron Nitride Monolayer

Cited by 67 publications

References 45 publications

Spin and valley control of free carriers in single-layer WS2

Spin and valley control of free carriers in single-layer WS2

Boron Nitride Nanostructures: Fabrication, Functionalization and Applications

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

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