Nanomechanical Architecture of Strained Bilayer Thin Films: From Design Principles to Experimental Fabrication

Huang, Minghuang; Boone, Carl; Roberts, Michelle; Savage, D. E.; Lagally, M. G.; Shaji, Nakul; Qin, Hua; Blick, Robert H.; Nairn, John A.; Liu, Feng

doi:10.1002/adma.200501353

Cited by 180 publications

(176 citation statements)

References 21 publications

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“…4 Roll-up nanotechnology has been proven as a convenient approach to fabricate micro/nanotubes, as reported previously. [5][6][7][8][9] By releasing the built-in mechanical stress, the rolling-up process induces the curving of the original flat films, thus resulting in the change of their strain status 10 in the rolled-up geometry 11 (SiGe/Si tubes or III-V tubes), which have been confirmed by micro-Raman scattering, 12 X-ray microdiffractions, 10,13,14 and photoluminescence spectroscopy. 15 Meanwhile, physical properties of semiconductor nanomembranes (NMs), 16,17 such as band structures, 18,19 and carrier mobilities, 20 could be altered by the intrinsic strain/stress.…”

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confidence: 88%

Uniaxial and tensile strained germanium nanomembranes in rolled-up geometry by polarized Raman scattering spectroscopy

et al. 2015

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We present a rolled-up approach to form Ge microtubes and their array by rolling-up hybrid Ge/Cr nanomembranes, which is driven by the built-in stress in the deposited Cr layer. The study of Raman intensity as a function of the angle between the crystal-axis and the polarization-direction of the scattered light, i.e., polarized Raman measurement reveals that the strain state in Ge tube is uniaxial and tensile, and can reach a maximal value 1.0%. Both experimental observations and theoretical calculations suggest that the uniaxial-tensile strain residual in the rolled-up Ge tubes correlates with their tube diameters, which can be tuned by the thicknesses of the Cr layers deposited. Using the polarized Raman scattering spectroscopy, our study provides a comprehensive analysis of the strain state and evolution in self-rolled-up nano/micro-tubes.

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confidence: 88%

Uniaxial and tensile strained germanium nanomembranes in rolled-up geometry by polarized Raman scattering spectroscopy

et al. 2015

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“…Lattice constant mismatch between a film and a substrate creates elastic strain, leading to the curling of the strip into a helical ribbon (6,21). These semiconductor helices, of 1 m in diameter and of tens of nanometers in thickness, are smaller than typical cholesterol ribbons.…”

Section: Indeed If S Is the Area Of The Middle Plane Of The Strip Tmentioning

confidence: 99%

“…T he elastic properties of meso-and nanoscale thin elastic strips forming helical ribbons or tubules, have been the focus of active recent research in both biophysics and nanoscience communities (1)(2)(3)(4)(5)(6)(7). We have discovered that in a number of complex aqueous solutions containing a sterol (cholesterol in particular) and a mixture of surfactants, the sterol molecules may self-assemble into ribbons of helical shape (8).…”

mentioning

confidence: 99%

Thickness–radius relationship and spring constants of cholesterol helical ribbons

Khaykovich

Kozlova

Choi

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Using quantitative phase microscopy, we have discovered a quadratic relationship between the radius R and the thickness t of helical ribbons that form spontaneously in multicomponent cholesterol-surfactant mixtures. These helical ribbons may serve as mesoscopic springs to measure or to exert forces on nanoscale biological objects. The spring constants of these helices depend on their submicroscopic thickness. The quadratic relationship (R ؔ t 2 ) between radius and thickness is a consequence of the crystal structure of the ribbons and enables a determination of the spring constant of any of our helices solely in terms of its observable geometrical dimensions.biological force spectroscopy ͉ elasticity of thin films ͉ phase-contrast microscopy in biophysics T he elastic properties of meso-and nanoscale thin elastic strips forming helical ribbons or tubules, have been the focus of active recent research in both biophysics and nanoscience communities (1-7). We have discovered that in a number of complex aqueous solutions containing a sterol (cholesterol in particular) and a mixture of surfactants, the sterol molecules may self-assemble into ribbons of helical shape (8). The geometry of the helical ribbons is characterized by the radius, width, thickness, contour length, and pitch angle, see figure 1a in ref. 9. Remarkably, the pitch angle is always either 11°or 54°, whereas axial length, width, and radius vary by two orders of magnitude in the range from 1 to Ϸ100 m. These helical ribbons are fascinating objects for fundamental studies (2,(8)(9)(10). Furthermore, because low-pitch helical ribbons have spring constants in the range of 0.5 to 500 pN/m (2), and the elongation of these springs from 1 m up to 100 m can easily be observed microscopically, it follows that they can be used as mesoscopic spring scales to measure forces between nanoscale biological objects in the range from 0.5 pN to 50 nN. For this and other applications, the ability to readily determine the spring constants of individual helixes is of crucial importance. In this article, we establish the relationship between the spring constant of the low-pitch cholesterol helical ribbons and its readily observable dimensions: width, radius, and length.Originally, it had been thought that cholesterol helical ribbons formed in surfactant mixtures had liquid crystalline structure and that their shape was governed by elastic properties of liquid crystalline layer (9,11,12). Recently, we have shown by X-ray diffraction that these helical ribbons are, in fact, single crystals with structure closely resembling that of cholesterol monohydrate (10). Having in mind the single-crystal nature of our ribbons, we have proposed that their helical shape is determined by a balance between two terms in the free energy of deformation of the cholesterol crystalline strip (2). The first term, the spontaneous bending energy, favors curling toward one of the two faces of the ribbon and is linear in curvature, ϪK s /R. The second term is the elastic energy of bending a strip. Thi...

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“…Bakri-Kassem et al fabricated a pre-stressed bilayer curled high-Q MEMS variable capacitor for use in tuning circuits, however, unlike the SC, the bilayer of their device was too short to form a ring or coil. 9 Other groups have fabricated rolled structures of strain mismatched bilayer films [10][11][12] which are structurally very similar to SC, but none of them explored the possibility of using those structures in any energy storage device. Various factors that determine rolling behavior, such as the direction of rolling and the shape of the final rolled structure of any strain mismatched bilayer films have also been identified and investigated in the literature.…”

Section: Introductionmentioning

confidence: 99%

The strain capacitor: A novel energy storage device

Shuvra

McNamara

2014

AIP Advances

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A novel electromechanical energy storage device is reported that has the potential to have high energy densities. It can efficiently store both mechanical strain energy and electrical energy in the form of an electric field between the electrodes of a strain-mismatched bilayer capacitor. When the charged device is discharged, both the electrical and mechanical energy are extracted in an electrical form. The charge-voltage profile of the device is suitable for energy storage applications since a larger portion of the stored energy can be extracted at higher voltage levels compared to a normal capacitor. Its unique features include the potential for long lifetime, safety, portability, wide operating temperature range, and environment friendliness. The device can be designed to operate over varied operating voltage ranges by selecting appropriate materials and by changing the dimensions of the device. In this paper a finite element model of the device is developed to verify and demonstrate the potential of the device as an energy storage element. This device has the potential to replace conventional energy storage devices.

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Nanomechanical Architecture of Strained Bilayer Thin Films: From Design Principles to Experimental Fabrication

Cited by 180 publications

References 21 publications

Uniaxial and tensile strained germanium nanomembranes in rolled-up geometry by polarized Raman scattering spectroscopy

Uniaxial and tensile strained germanium nanomembranes in rolled-up geometry by polarized Raman scattering spectroscopy

Thickness–radius relationship and spring constants of cholesterol helical ribbons

The strain capacitor: A novel energy storage device

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