Large Frequency Change with Thickness in Interlayer Breathing Mode—Significant Interlayer Interactions in Few Layer Black Phosphorus

Luo, Xin; Lu, Xin; Koon, Gavin Kok Wai; Neto, A. H. Castro; Özyilmaz, Barbaros; Xiong, Qihua; Quek, Su Ying

doi:10.1021/acs.nanolett.5b00775

Cited by 108 publications

(145 citation statements)

References 42 publications

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“…7,9,33 They can be categorized into two types: in-plane shear and out-of-plane breathing vibration modes. Due to their greater sensitivity to interlayer coupling, LF Raman modes can directly probe the interfacial coupling, and they have been found as more effective indicators of the layer thickness [34][35][36][37][38][39][40][41][42][43][44][45][46] and stacking 24,[47][48][49][50][51][52][53][54][55] for diverse 2D materials. LF Raman spectroscopy is a rapidly developing field of research and has accelerated due to recent development of volume Bragg gratings for ultra-narrow optical filters with bandwidth about 1 cm -1 , which allows efficient cut-off of the excitation laser light without employing expensive triple monochromators for LF Raman measurements.…”

Section: Introductionmentioning

confidence: 99%

Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials

et al. 2017

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Two-dimensional (2D) layered materials have been extensively studied owing to their fascinating and technologically relevant properties. Their functionalities can be often tailored by the interlayer stacking pattern. Low-frequency (LF) Raman spectroscopy provides a quick, non-destructive and inexpensive optical technique for stacking characterization, since the intensities of LF interlayer vibrational modes are sensitive to the details of the stacking. A simple and generalized interlayer bond polarizability model is proposed here to explain and predict how the LF Raman intensities depend on complex stacking sequences for any thickness in a broad array of 2D materials, including graphene, MoS 2 , MoSe 2 , NbSe 2 , Bi 2 Se 3 , GaSe, h-BN, etc. Additionally, a general strategy is proposed to unify the stacking nomenclature for these 2D materials.Our model reveals the fundamental mechanism of LF Raman response to the stacking, and provides general rules for stacking identification.

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Section: Introductionmentioning

confidence: 99%

Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials

et al. 2017

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“…[68][69][70] For example, with different thicknesses, anisotropic effect of the interlayer coupling has been demonstrated because of a strong orientation-dependence of the lattice constant. [68][69][70] For example, with different thicknesses, anisotropic effect of the interlayer coupling has been demonstrated because of a strong orientation-dependence of the lattice constant.…”

Section: Optical Propertiesmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Recent developments in black phosphorus transistors

2015

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The discovery of graphene has inspired great research interest in two-dimensional (2D) layered nanomaterials during the past decade. As one of the newest members in 2D layered nanomaterials family, black phosphorus (BP), with puckered structure similar to graphene, has shown great potential in novel nanoelectronics owing to its thickness-dependent bandgap. Especially, the unique in-plane anisotropy and high carrier mobility enable BP to be a promising candidate for field-effect transistor (FET) applications. In addition, monolayer or few-layer BP can be combined into van de Waal heterostructures and this opens up a pathway for overcoming existing problems such as impurity scattering and surface degradation or achieving functionalities. In this article, we will review typical physical and chemical properties of BP and provide an overview of the recent development in BP-based transistors. With this review, we also discuss the current challenges in BP transistors and future research directions.2 interactions between adjacent layers. 3 For example, as a typical representative of transition metal dichaldogenides (TMDs), MoS 2 with a relatively large intrinsic bandgap of 1.8 eV shows superior on/off ratio and ultralow standby power dissipation. 4 Generally, MoS 2 exhibits n-type characteristics because of the presence of S vacancies and strong Fermi-level pinning near the conduction band, 5 and has great potential in practical electronic and optoelectronic applications. 6 However, in spite of many promising theoretical predications, the observed mobility of TMDs based device is still relatively low due to the heavy effective mass of carriers and the scattering mechanisms, especially the phonon scattering at room temperature. 7, 8 Thus, the majority of TMDs materials have not been demonstrated for high-performance radio frequency (RF) transistors. 3At the beginning of 2014, black phosphorus (BP), one of the latest members of 2D layered semiconducting materials has been rediscovered from the perspective of 2D materials for transistors. 9 Although BP was discovered a century ago, there have been only a few studies focusing on the utilization of BP due to the difficulty in synthesis. 10 Recently, it has been found that the moderate and tunable bandgap of BP provides an alternative for next generation nanoelectronic applications. Similar to graphene, single-layered or few-layered black phosphorus can be obtained by mechanical exfoliation and they exhibit unexpected properties compared with their bulk counterpart. Moreover, as a single-elemental layered material, BP possesses lower spin-orbit coupling because of relatively lighter phosphorus atom, which is more favourable for spin transport. 11The atomic structure and properties of main 2D layered materials are listed in Table 1, in which we select MoS 2 as a representative of TMDs. We also highlight hexagonal boron nitride (h-BN) as a graphite-type structured material, which a good gate insulator for 2D materials based FETs because of its ultra-flat and charged impurity-fre...

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“…In contrast to other layered 2D materials such as transition metal dichalcogenides (TMDs) and graphene in BP the bonding between the consecutive layers is not purely of the van der Waals type 33 . In BP atoms forms covalent bonds with three intralayer neighbors leaving a pair of lone electrons dangling out into the interlayer vacuum region 34,35 . This results in enhanced interlayer interaction giving rise to a strong thickness dependence of the band gap 36 and is also the main reason for the strong surface reactivity in air.…”

Section: Introductionmentioning

confidence: 99%

The impact of hexagonal boron nitride encapsulation on the structural and vibrational properties of few layer black phosphorus

Birowska¹,

Urban²,

Baranowski³

et al. 2019

Nanotechnology

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The encapsulation of two-dimensional layered materials such as black phosphorus is of paramount importance for their stability in air. However, the encapsulation poses several questions, namely, how it affects, via the weak van der Waals forces, the properties of the black phosphorus and whether these properties can be tuned on demand. Prompted by these questions, we have investigated the impact of hexagonal boron nitride encapsulation on the structural and vibrational properties of few layer black phosphorus, using a first-principles method in the framework of density functional theory. We demonstrate that the encapsulation with hexagonal boron nitride imposes biaxial strain on the black phosphorus material, flattening its puckered structure, by decreasing the thickness of the layers via the increase of the puckered angle and the intra-layer P-P bonds. This work exemplifies the evolution of structural parameters in layered materials after the encapsulation process. We find that after encapsulation, phosphorene (single layer black phosphorous) contracts by 1.1% in the armchair direction and stretches by 1.3% in the zigzag direction, whereas few layer black phosphorus mainly expands by up to 3% in the armchair direction. However, these relatively small strains induced by the hexagonal BN, lead to significant changes in the vibrational properties of black phosphorus, with the redshifts of up to 10 cm −1 of the high frequency optical mode A 1 g . In general, structural changes induced by the encapsulation process open the door to substrate controlled strain engineering in two-dimensional crystals.

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Large Frequency Change with Thickness in Interlayer Breathing Mode—Significant Interlayer Interactions in Few Layer Black Phosphorus

Cited by 108 publications

References 42 publications

Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials

Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials

Recent developments in black phosphorus transistors

The impact of hexagonal boron nitride encapsulation on the structural and vibrational properties of few layer black phosphorus

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