Spatial mapping of multimode Brownian motions in high-frequency silicon carbide microdisk resonators

Wang, Zenghui; Lee, Jae-Sung; Feng, Philip X.‐L.

doi:10.1038/ncomms6158

Cited by 82 publications

(78 citation statements)

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“…As shown in Figures 2e-i, the multimode resonance frequencies range from 5.2 MHz to~13 MHz with Qs from 20 to 54. To understand the mechanical properties and resonance behaviors of the 2D h-BN resonators in detail, we further investigate the multimode resonances and their vibrational mode shapes using scanning spectromicroscopy techniques 32 . We scan the 633 nm red laser over the device area and measure the amplitudes of reflected light intensity.…”

Section: Resultsmentioning

confidence: 99%

“…Ultrasensitive detection of multimode Brownian motion using high spatial-resolution scanning optical interferometric spectromicroscopy 32 likely remains the best technique for unveiling these subtle features. To effectively probe the detailed structural properties, less light absorption is always advantageous for minimal parasitic thermal stress induced by photothermal heating, which can obscure the intrinsic device characteristics.…”

Section: Methodsmentioning

confidence: 99%

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Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

2017

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Atomic layers of hexagonal boron nitride (h-BN) crystal are excellent candidates for structural materials as enabling ultrathin, two-dimensional (2D) nanoelectromechanical systems (NEMS) due to the outstanding mechanical properties and very wide bandgap (5.9 eV) of h-BN. In this work, we report the experimental demonstration of h-BN 2D nanomechanical resonators vibrating at high and very high frequencies (from~5 to~70 MHz), and investigations of the elastic properties of h-BN by measuring the multimode resonant behavior of these devices. First, we demonstrate a dry-transferred doubly clamped h-BN membrane with 6.7 nm thickness, the thinnest h-BN resonator known to date. In addition, we fabricate circular drumhead h-BN resonators with thicknesses ranging from~9 to 292 nm, from which we measure up to eight resonance modes in the range of~18 to 35 MHz. Combining measurements and modeling of the rich multimode resonances, we resolve h-BN's elastic behavior, including the transition from membrane to disk regime, with built-in tension ranging from 0.02 to 2 N m − 1 . The Young's modulus of h-BN is determined to be E Y ≈392 GPa from the measured resonances. The ultrasensitive measurements further reveal subtle structural characteristics and mechanical properties of the suspended h-BN diaphragms, including anisotropic built-in tension and bulging, thus suggesting guidelines on how these effects can be exploited for engineering multimode resonant functions in 2D NEMS transducers.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

2017

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“…38 The measurement techniques and the system have been engineered to achieve displacement sensitivities of ~36 fm/Hz 1/2 (calibrated for these black P devices) and submicron spatial resolution, and are thus capable of precisely mapping and vividly discerning the mode shapes of multimode resonators. 38,39 Using this system, multimode resonances of black P nanoresonators are first characterized spectrally by performing microspectroscopy, harnessing frequency-domain multimode resonances for a given positioning of the readout laser spot. 39 Figure 1d depicts the 6 resonant modes observed in a circular device (Figure 1c, diameter d=10.0 μm, thickness t=95 nm) in the range from 10 to 50 MHz.…”

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“…38,39 Using this system, multimode resonances of black P nanoresonators are first characterized spectrally by performing microspectroscopy, harnessing frequency-domain multimode resonances for a given positioning of the readout laser spot. 39 Figure 1d depicts the 6 resonant modes observed in a circular device (Figure 1c, diameter d=10.0 μm, thickness t=95 nm) in the range from 10 to 50 MHz. The AC excitation voltages are 50 mV rms for Mode #1, 200 mV rms for Modes #2 and #3, and 1.2 V rms for Modes #4, #5 and #6 to accommodate the fact that at higher modes, the same driving force would lead to smaller displacements.…”

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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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“…-5-Through carefully engineering the optical interferometric motion-signal transduction, we achieve ~10fm/Hz 1/2 -level displacement sensitivity for these devices, approaching the best interferometric displacement sensitivities enabled by SiC devices. 31 To demonstrate electrically driven black P nanoelectromechanical resonators, we apply a voltage signal between the black P flake's electrode and the back gate, which includes a DC polarization component V g (from a DC power supply) and an AC component (output from a network analyzer, with amplitude V g and frequency ω/2π). The gate voltage generates a periodic driving force…”

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Black phosphorus nanoelectromechanical resonators vibrating at very high frequencies

et al. 2015

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-2-Black phosphorus (P) is a layered material in which individual atomic layers of P are stacked together by weak van der Waals forces (similar to bulk graphite) 1 . Inside a single layer, each P atom is covalently bonded with three adjacent P atoms to form a corrugated plane of honeycomb structure (Fig. 1a, note top view of each crystal plane is in honeycomb structure). The three bonds take up all three valence electrons of P (different than graphene and graphite). This makes monolayer black P ('phosphorene') a semiconductor with a direct bandgap of ~2eV. The bandgap is reduced in few-layer phosphorene, and becomes ~0.3eV for bulk black P. 2,3,4,5,6,7,8 The bandgap and its dependence on thickness has brought mono-and few-layer phosphorene to the family of 2D crystals, especially for enabling field-effect transistors (FETs) 9,10,11,12 and optoelectronic devices with potential applications in the infrared regime, 13,14 with prototypes recently demonstrated.In parallel to its potential for making novel electronic and optoelectronic devices, black P possesses attractive mechanical properties that are unavailable in other peer materials: it has very large strain limit (30%), and is much more stretchable (Young's modulus of E Y =44GPa for single layer) than other layered materials (e.g., E Y =1TPa for graphene), especially in the armchair direction (x axis in Fig. 1a). 15Such superior mechanical flexibility, 15,16,17 together with the exotic negative Poisson's ratio 18 arising from its corrugated atomic planes, offers unique opportunities for effectively inducing and controlling sizable strains, and thus the electronic, optoelectronic, and thermoelectric properties in this nanomaterial. 19,20,21,22,23 For example, with a 2D tension (in N/m, as in surface tension) of 0. and frequency-shift-based resonant infrared sensors. 28To date, however, the exploration and implementation of black P mechanical devices have not yet been reported; such efforts have been plagued by the relative chemical activeness of black P:8 , 9 it can be readily oxidized in air, and the multiple processing steps (many involving wet chemistry) required in fabricating mechanical devices from layered 2D materials (lithography, metallization, etching and suspension, etc.) make it particularly challenging to preserve the quality of black P crystal throughout the process. Here, we make the initial experimental study on exploring and exploiting the mechanical properties of black P to realize the first robust black P crystalline nanomechanical devices, by employing a set of specially-engineered processing and measurement techniques. We fabricate suspended black P NEMS resonators with electrical contacts using a facile dry transfer technique, minimizing sample exposure to the ambient and completely avoiding chemical processes. We characterize the material properties in vacuum, and implement nanomechanical measurements on the black P NEMS resonators using a number of experimental schemes, including Brownian motion-induced thermomechanical resonance, elec...

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Spatial mapping of multimode Brownian motions in high-frequency silicon carbide microdisk resonators

Cited by 82 publications

References 54 publications

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

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

Black phosphorus nanoelectromechanical resonators vibrating at very high frequencies

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