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Monolayer MoS? Strained to 1.3% With a Microelectromechanical System
摘要： We report on a modified transfer technique for atomically thin materials integrated into microelectromechanical systems (MEMS) for studying strain physics and creating strain-based devices. Our method tolerates the non-planar structures and fragility of MEMS while still providing precise positioning and crack-free transfer of flakes. Furthermore, our method used the transfer polymer to anchor the 2D crystal to the MEMS, which reduces the fabrication time and increases the yield, and allowed us to exploit the strong mechanical coupling between the 2D crystal and polymer to strain the atomically thin system. We successfully strained single atomic layers of molybdenum disulfide (MoS2) with MEMS devices for the first time and achieved greater than 1.3% strain, marking a major milestone for incorporating 2D materials with MEMS. We used the established strain response of MoS2 Raman and photoluminescence spectra to deduce the strain in our crystals and provide a consistency check. We found good comparison between our experiment and the literature.
关键词： photoluminescence,Raman,strain,monolayer MoS2,MEMS
更新于2025-09-23 15:22:29
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Cascaded Two-core PCFs based In-line Fiber Interferometer for Simultaneous Measurement of Strain and Temperature
摘要： A new fiber sensor configuration based on the cascaded in-line fiber interferometers has been proposed and experimentally demonstrated for simultaneous measurement of strain and temperature. In order to make the cascaded in-line interferometers, we used two different types of two-core photonic crystal fibers (TCPCFs) having two cores in the symmetry and asymmetry structures. The TCPCFs have different transmission characteristics owing to the distinct geometric structures of the integrated cores, this causes the different strain and temperature sensitivities and thus the two parameters can be discriminated. The measurement resolutions are achieved to be 11.1 με and 1.10 oC for strain and temperature, respectively, in the 10 pm wavelength resolution.
关键词： Mach-Zehnder interferometer,Two-core photonic crystal fiber,strain and temperature sensor
更新于2025-09-23 15:22:29
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Tailorable and Flexible Conducting Films via Interfacial Modification of Polymer Fibers
摘要： Portable devices have become lightweight, flexible, and even stretchable such that skin-like electronics are widely applicable, including in biomedical devices, soft robotics, and human/machine interfaces. Rendering these devices soft and flexible is highly desirable, as this would enable them to interact seamlessly with human skin and improve their wearing comfort. We demonstrate a convenient but effective method to fabricate flexible conducting films. These films consist of electrospun polyurethane (PU) fibers as the flexible substrate onto which copper was deposited. These Cu-PU films have excellent conductivity, and their resistance only increases slightly after extensive folding, even when folded into a paper crane with a resistance of 1.8 Ω. Furthermore, Cu-PU films can sense tension strength and exhibit stable Joule electrothermal performance. The Cu-PU-based heating glove could be heated to 40 °C in 30 s by applying 2 V. The simple but effective procedure presented here is suitable to fabricate flexible conducting film and may also promote the development of portable and flexible electronic products.
关键词： flexible,polymer fiber,strain sensor,conductive,interfacial modification
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Biaxial Strain based Performance Modulation of Negative-Capacitance FETs
摘要： In this work, we report device simulations conducted to study the performance of biaxially strained ferroelectric-based negative capacitance FETs (NCFETs). We adopted PbZr0.5Ti0.5O3 (PZT) and HfO2 as ferroelectric materials and applied biaxial strain using the first-principles method. It was found that PZT and HfO2 show different trends in the negative capacitance (NC) region under biaxial strain. Biaxial strain strongly affects the NC of PZT, whereas HfO2 is not as susceptible to biaxial strain as PZT. When no strain is applied, HfO2-based NCFETs exhibit a better performance than PZT-based NCFETs. However, the subthreshold slope and ON-state current are improved in the case of PZT-based NCFETs when the compressive biaxial strain is increased, whereas the performance of HfO2-based NCFETs is slightly degraded. In particular, the negative drain-induced barrier lowering and negative differential resistance vary considerably when compressive strain is applied to PZT-based NCFETs.
关键词： strain,negative capacitance FETs,ferroelectrics,density functional theory,HfO2,PZT
更新于2025-09-23 15:22:29
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Microstructural Evolution in SAC305 and SAC-Bi Solders Subjected to Mechanical Cycling
摘要： Fatigue failure of solder joints is one of the most common methods by which electronic packages fail. Electronic assemblies usually must cope with a temperature varying environment. Due to the mismatches in coefficients of thermal expansion (CTEs) of the various assembly materials, the solder joints are subjected to cyclic thermal-mechanical loading during temperature cycling. The main focus of this work is to investigate the changes in microstructure that occur in SAC305 and SAC+Bi lead free solders subjected to mechanical cycling. In this paper, we report on results for the SAC+Bi solder commonly known as SAC_Q or CYCLOMAX. Uniaxial solder specimens were prepared in glass tubes, and the outside surfaces were polished. A nanoindenter was then used to mark fixed regions on the samples for subsequent microscopy evaluation. The samples were subjected to mechanical cycling, and the microstructures of the selected fixed regions were recorded after various durations of cycling using Scanning Electron Microscopy (SEM). Using the recorded images, it was observed that the cycling induced damage consisted primarily of small intergranular cracks forming along the subgrain boundaries within dendrites. These cracks continued to grow as the cycling continued, resulting in a weakening of the dendrite structure, and eventually to the formation of large transgranular cracks. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged.
关键词： Bismuth,Microstructure,SAC Alloy,Hysteresis,Evolution,Lead Free Solder,Cyclic Stress-Strain Curve
更新于2025-09-23 15:22:29
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Experimental study and prediction on impact scratching of single abrasive for K9 glass
摘要： The orthogonal test L16 (43) was designed, and the impact scratching experiment for K9 glass was carried out by using Vickers diamond indenter on the DMG ULTRASONIC 70-5 linear. The three-dimensional morphology of the surface for glass was observed by scanning electron microscope (SEM), which was compared with that in the quasi static state. The strain rate of the grinding process was obtained by choosing the contact zone length as the impact contact length, which was the evaluation Index of impact. The relationships between strain rate and the depth of radial crack, strain rate and the depth of transverse crack, strain rate and normal scratching force were first analysed. The results showed that the depth of radial of crack, the depth of transversal crack and the normal scratching force decreased with the increase of strain rate. The two-layer BP neural network was established, which took the strain rate as input variables. The depth of radial crack, the depth of transversal crack and normal scratching force were predicted and the errors were within 10%, which indicated that the prediction results of BP neural network were reliable.
关键词： impact scratching,depth of crack,strain rate,BP neural network,K9 glass
更新于2025-09-23 15:22:29
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Quantum Calligraphy: Writing Single-Photon Emitters in a Two-Dimensional Materials Platform
摘要： We present a paradigm for encoding strain into two dimensional materials (2DM) to create and deterministically place single photon emitters (SPEs) in arbitrary locations with nanometer-scale precision. Our material platform consists of a 2DM placed on top of a deformable polymer film. Upon application of sufficient mechanical stress using an atomic force microscope tip, the 2DM/polymer composite deforms, resulting in formation of highly localized strain fields with excellent control and repeatability. We show that SPEs are created and localized at these nanoindents, and exhibit single photon emission up to 60K, the highest temperature reported in these materials. This quantum calligraphy allows deterministic placement and real time design of arbitrary patterns of SPEs for facile coupling with photonic waveguides, cavities and plasmonic structures. In addition to enabling versatile placement of SPEs, these results present a general methodology for imparting strain into 2DM with nanometer-scale precision, providing an invaluable tool for further investigations and future applications of strain engineering of 2DM and 2DM devices.
关键词： tungsten disulfide,atomic force microscopy,two-dimensional materials,single photon emitter,strain engineering
更新于2025-09-23 15:22:29
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Strain-optoelectronic coupling properties of externally deformed nanoribbons with embedded quantum well
摘要： Strain-engineering provides a critical mechanism for tuning the band structure of quantum wells (QWs). However, due to the inherent rigidity of the semiconductor materials, the strain induced by lattice-mismatch is restricted to be invariable, uniform, thus cannot be subject to direct mechanical loading processes. Therefore, the flexible nanoribbons (NRs) in a variety of configurations offer entirely new research perspectives in modulation of the optoelectronic characteristic of QWs by curvature-induced inhomogeneous strain. In this paper, we propose a strategy to fabricate the QW layer embedded in uniaxially wavy NRs. To thoroughly figure out the internal strain-optoelectronic coupling mechanism, we establish a simple and accurate calculation model for externally deformed QW NRs using the eight-band k·p perturbation method for the first time. Luttinger-Kohn-Pikus-Bir Hamiltonian (LKPBH) for strained semiconductor is adopted and solved by finite-difference method (FDM). Theoretical calculations reveal inclined band edges, which result in the quantum-confined stark effect (QCSE) in the bended QW NRs. Continuously and periodically varied band gap of the wavy QW is revealed with a blue-shift from peak to valley of the sample NR, which agrees well with the μ-photoluminescence measurements. Further adjustments of the external configuration are explored to study the impact of the larger deformed structure on the curvature and band gap of the wavy QW within the confinement of the fracture limit.
关键词： nanoribbons,optoelectronic,strain,k·p method,quantum well
更新于2025-09-23 15:22:29
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Valley engineering by strain in Kekulé-distorted graphene
摘要： A Kekulé bond texture in graphene modi?es the electronic band structure by folding the Brillouin zone and bringing the two inequivalent Dirac points to the center. This can result in the opening of a gap (Kek-O) or the locking of the valley degree of freedom with the direction of motion (Kek-Y). We analyze the effects of uniaxial strain on the band structure of Kekulé-distorted graphene for both textures. Using a tight-binding approach, we introduce strain by considering the hopping renormalization and corresponding geometrical modi?cations of the Brillouin zone. We numerically evaluate the dispersion relation and present analytical expressions for the low-energy limit. Our results indicate the emergence of a Zeeman-like term due to the coupling of the pseudospin with the pseudomagnetic strain potential which separates the valleys by moving them in opposite directions away from the center of the Brillouin zone. For the Kek-O phase, this results in a competition between the Kekulé parameter that opens a gap and the magnitude of strain which closes it, while for the Kek-Y phase, it results in a superposition of two shifted Dirac cones. As the Dirac cones are much closer in the superlattice reciprocal space than in pristine graphene, we propose strain as a control parameter for intervalley scattering.
关键词： Brillouin zone,tight-binding,strain,graphene,valley engineering,Kekulé distortion
更新于2025-09-23 15:22:29
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Strain-Engineered Ultrahigh Mobility in Phosphorene for Terahertz Transistors
摘要： Carrier mobility is a key parameter for the operation of electronic devices as it determines the ON state current and switching speed/frequency response of transistors. 2D phosphorene is considered as a potential candidate for field-effect transistors due to its high mobility. Here it is proposed to further enhance the carrier mobility of phosphorene and device performance via strain engineering. A systematic ab initio investigation on the anisotropic electronic structure of few-layer phosphorene reveals that the monolayer under 7.5–10% strain along zigzag direction shows an exceptional carrier mobility of ≈106 cm2 V?1 s?1, which is 10 times higher than the strain-free case. The simulated device performance shows that strain-engineered phosphorene–based field-effect transistors demonstrate a cut-off frequency of ≈1.14 THz with a gate length of 1.0 micron and 112 THz with a sub-10 nm gate length.
关键词： carrier mobility,density functional theory,phosphorene,transistors,strain-engineered electronics
更新于2025-09-23 15:22:29