Mechanical and Electrical Anisotropy of Few-Layer Black Phosphorus

Jin, Tao; Shen, Wanfu; Wu, Sen; Liu, Lu; Feng, Zhihong; Wang, Chao; Hu, Chunguang; Yao, Pei; Zhang, Hao; Pang, Wei; Duan, Xuexin; Liu, Jing; Zhou, Chongwu; Zhang, Daihua

doi:10.1021/acsnano.5b05151

Cited by 280 publications

(286 citation statements)

References 47 publications

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“…To validate the multimode resonance determination of crystal orientation, we further independently verify this by using polarized optical reflectance measurements. 34,28,40 The results (Figure 2d) show excellent agreement with the results in Figure 2c. This demonstrates that the spatially-resolved multimode resonances provide a new useful alternative for determining the crystal orientation, in situ, in the device platform of suspended black P nanostructures.…”

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confidence: 81%

“…28 However, unlike in Si (where the crystal orientation is always indicated by the cuts on Si wafers with good precision), 5 such information is not readily available for 2D nanocrystals, and complete mechanical decoupling between the two axes has not yet been achieved. 28 In this work, enabled by the first demonstration of black P resonant nanostructures with multimode responses, we show that the spatial mapping of the multimode resonance mode shapes creates a new means for the precise determination of black P crystal orientation (i.e., the Wang Z.H., Jia H., Zheng X.-Q., Yang R., Ye G.J., Chen X.H., Feng P.X.-L., Nano Letters 16, 5394-5400 (2016) [Accepted Version] DOI: 10.1021/acs.nanolett.6b01598, Online Publication: August 9, 2016-3-anisotropic zigzag and armchair axes). This is completely independent of conventional optical and electrical methods that require either polarized optical spectroscopic measurements 29 , 30 , 31 , 32 , 33 , 34 or device structures with many electrodes along multiple directions.…”

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confidence: 99%

“…27 Nevertheless, for anisotropic crystal such as black P, prior knowledge of the crystal direction is required for fabricating specifically-orientated indentation samples that attempt to mechanically decouple the two crystal axes. 28 However, unlike in Si (where the crystal orientation is always indicated by the cuts on Si wafers with good precision), 5 such information is not readily available for 2D nanocrystals, and complete mechanical decoupling between the two axes has not yet been achieved. 28 In this work, enabled by the first demonstration of black P resonant nanostructures with multimode responses, we show that the spatial mapping of the multimode resonance mode shapes creates a new means for the precise determination of black P crystal orientation (i.e., the anisotropic zigzag and armchair axes).…”

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confidence: 99%

“…35,36 Furthermore, our technique enables simultaneous quantification of the anisotropic mechanical properties, i.e., elastic moduli along both major crystal axes, without sophisticated device fabrication requiring predetermined crystal orientation. 28 Black P resonant nanostructures are fabricated by employing an all-dry-transfer method with crystals synthesized in a high-temperature and high-pressure process. 37,38 Black P crystals are mechanically exfoliated onto a viscoelastic (polydimethylsiloxane, PDMS) stamp, and the candidate flakes are quickly identified and transferred (with alignment) onto microtrenches (depth of ~290 nm) prefabricated on a SiO 2 -Si substrate with adjacent electrodes.…”

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Resolving and Tuning Mechanical Anisotropy in Black Phosphorus via Nanomechanical Multimode Resonance Spectromicroscopy

et al. 2016

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Black phosphorus (P) has emerged asWang Z.H., Jia H., Zheng X.-Q., Yang R., Ye G.J., Chen X.H., Feng P.X.-L., Nano Letters 16, 5394-5400 (2016) [Accepted Version] DOI: 10.1021/acs.nanolett.6b01598, Online Publication: August 9, 2016-2-Efficiently exploiting anisotropic properties in crystals plays important roles in many areas in science and technology, ranging from timing and signal processing using a rich variety of crystalline cut orientations in quartz to the modulation and conversion of light using anisotropic crystals. In state-of-the-art miniature devices and integrated systems, crystalline anisotropy enables a number of important dynamic characteristics in microelectromechanical systems (MEMS) such as gyroscopes, rotation rate sensors, and accelerometers. 1,2,3,4 Single crystal silicon (Si), the hallmark of semiconductors and the most commonly used crystal in MEMS, possesses clear mechanical anisotropy that has been extensively characterized and utilized (e.g., Young's moduli in the <110> and <100> directions are E Y<110> = 169 GPa and E Y<100> = 130 GPa). 5 , 6 As devices continue to be scaled down to nanoscale, anisotropy in mechanical properties may not always be readily preserved at device level due to lattice defects or surface effects, 7 , 8 , 9 and thus remain largely unexplored in emerging nanoelectromechanical systems (NEMS) built upon conventional crystals.The recent advent of atomic-layer crystals offer exciting opportunities for building twodimensional (2D) NEMS using single-crystal layered materials, in which many desired material properties are preserved, or even intensified, as the crystal thickness approaches genuinely atomic scale. One unique crystal is black phosphorus (P), not only a single-element directbandgap semiconductor with bandgap depending on the number of atomic layers (covering a wide range from visible light to IR) and with high carrier mobility, but also hitherto the bestknown atomic-layer crystal with strong in-plane anisotropy. The intrinsically anisotropic lattice structure (Figure 1a) of black P dictates a number of anisotropic material properties. In particular, it is theoretically predicted to exhibit in-plane mechanical anisotropy ( Figure 1a) 10,11,12,13 much stronger than that of Si, which shall lead to previously inaccessible dynamic responses in resonant NEMS 14 and new opportunities for studying carrier-lattice interaction in atomic layers. 15,16,17,18,19 To date, while extensive and rapidly growing efforts have been devoted to studying optical and electrical properties of black P and anisotropic effects in such devices, experiments on black P mechanical devices and mechanical anisotropic effects therein have been lacking. It is therefore of both fundamental and technological importance to systematically investigate the mechanical anisotropy in black P crystal.In bulk materials, such as crystalline Si, mechanical anisotropy is often characterized by measuring the sound velocity in different directions, 20,21,22,23 and fitting data to the Christoff...

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confidence: 99%

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confidence: 99%

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Resolving and Tuning Mechanical Anisotropy in Black Phosphorus via Nanomechanical Multimode Resonance Spectromicroscopy

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“…1 Phosphorene (PE) [1][2][3] -the crystalline two-dimensional (2D) material exfoliated from black phosphorous (BP) [4] -is attracting tremendous interest due to its exceptional electrical attributes, which include a high hole mobility (∼1,000 cm 2 /Vs) [1], and its unique anisotropic in-plane mechanical, optical and thermal properties [5][6][7][8][9][10][11][12][13]. If strain is introduced in PE, further tuning of its exceptional properties can be achieved [14][15][16][17].…”

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