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Strain distribution induced in SOI photonic substrate by through silicon via using advanced scanning X-ray nano-diffraction
摘要： In 3D Integration, dice are vertically interconnected with Through Silicon Via (TSV), which consist in holes etched in a thinned silicon substrate and filled with copper. This process induces thermal strain in surrounding silicon. New trends in 3D Integration imply the fabrication of Si photonic devices like waveguides in Silicon-On-Insulator (SOI) substrates containing TSVs. Thus, a quantitative analysis of strain in active areas around TSVs is mandatory. In this study, the strain induced by the TSVs in both the bulk silicon and the SOI layer was investigated using advanced scanning X-ray nano-diffraction. The crystallographic orientation offset between the separated silicon areas allows to decorrelate the strain in the Si layer of SOI and Si substrate. Using synchrotron radiation, two-dimensional quicK continuous Mapping (K-Map) of the strain in a region of 50μmx50μm with 500 nm spatial resolution was performed around a single TSV, at room temperature and during in situ annealing at 460°C. The strain field induced by the TSV appears negligible in both silicon areas. The effect of in situ annealing on the strain distribution is surprisingly weak. In the SOI active layer, the strain map mimics the surface pattern generated by the photonic devices processed at high temperature in this thin layer.
关键词： Through-Silicon Via,strain map,thermomechanical stress,Silicon photonics
更新于2025-09-10 09:29:36
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A demonstration of the mechanical sensing capability of individually contacted vertical piezoelectric nanowires arranged in matrices
摘要： This paper reports the fabrication of arrays of vertical piezoelectric nanowires which are individually contacted at their base, and demonstrates that an electrical response to strain can be obtained from individual nanowires from the array, without external biasing exploiting the piezotronic effect. Such a technology could thus be used for the fabrication of self-powered sensors for mechanical strain mapping, where each individually contacted nanowire would act as the strain sensing equivalent of a pixel. Lateral mapping resolutions in the micrometer range can be obtained. Here, the hydrothermal method was used to grow vertical ZnO nanowires selectively between two electrodes that had been patterned beforehand. For the sake of demonstration, nanowires deflection was produced by subjecting the array of nanowires to an incident lateral gas flow of controlled rate, which was switched on and off repeatedly across the sample while electrical response was measured. Different experimental configurations were tested in terms of flow rate, flow orientation, or nanowire position with respect to tube outlet. Experiments were carried out with compressed nitrogen and air. The experimental results are fully consistent with the piezoelectric and piezotronic response which can be expected with this geometry. Moreover, it is shown that the electrical response under nitrogen flow is a linear function of flow rate and that its sign provides information about flow direction. These results demonstrate the very promising prospects of this new technology for high-resolution mapping, with potential applications in gas or liquid flow sensing, fingerprints detection or human-machine interfaces.
关键词： Mechanical sensor,Piezotronics,Microfabrication,Strain mapping,ZnO nanowires
更新于2025-09-10 09:29:36
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I–V characteristics and conductance of strained SWCNTs
摘要： We present a new procedure to investigate the I–V characteristics and the conductance for strained SWCNTs. These electronic transport properties have been studied theoretically at zero temperature for zig-zag, armchair and chiral SWCNTs under the effect of the uniaxial tension and torsional strain. The analytical expression of the energy spectrum in the tight binding approximation has been used to calculate the induced current and the conductance through Landauer–Büttiker formalism. It is shown that the conductance for unstrained CNTs at initial values of the voltage can take discrete values which are equal to zero and 4 (e2/h) for semiconducting and conducting SWCNTs respectively. The emergence of the kinks in the I–V characteristics is due to the discrete electronic spectrum in the SWCNTs. The location and number of kinks are changeable under the effect of strain process. The conductance in a strained armchair (5, 5) CNT decreases to zero under torsional strain, consequently, it will transform the conducting SWCNTs at a threshold value of strain to a semiconducting SWCNT. In contrast, by applying the uniaxial tension on the armchair (5, 5) CNT, the conductance does not change absolutely. There is a different behavior can be observed by applying the strain on zig-zag (10, 0) CNT, where the conductance decreases rapidly and slightly under the in?uence of uniaxial tension and torsional strain, respectively. We found that the conductance of chiral (10, 9) CNT is not signi?cantly affected by applying the strain under consideration. More interestingly, the band structure of chiral (10, 9) CNT under uniaxial tension and torsional strain have been investigated within the tight binding approximation.
关键词： I–V characteristics,Mechanical strain,Tight binding approximation,SWCNT,Conductance
更新于2025-09-10 09:29:36
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Site occupancy and electric-field induced strain response of Er-doped (Bi0.4Na0.4Sr0.2)TiO3 ceramics
摘要： Er-doped (Bi0.4Na0.4Sr0.2)TiO3 powders were prepared by solid state reactions according to A-site donor (Bi0.4-x/3Na0.4-x/3Sr0.2-x/3Erx)TiO3 (x ? 0.0.015 and 0.02) and B-site acceptor (Bi0.4Na0.4Sr0.2)Ti1-yEryO3 (y ? 0, 0.015 and 0.02) substitutional doping mechanisms. In both cases, room-temperature X-ray diffraction analyses revealed a decrease of the unit cell volume with increasing Er contents, suggesting A-site occupancy to be thermodynamically more favourable. Over the 25e175 (cid:2)C temperature range, A-site doped ceramics, in particular x ? 0.015, showed enhanced thermal stability of the maximum achievable electric-?eld induced strain. Importantly, this minor doping level also reduced dielectric loss at high temperature and led to a transition from non-ergodic to ergodic relaxor behaviour. These results may further motivate the study of the impact of other minor dopants in this family of Pb-free piezoceramics.
关键词： Erbium,Strain,Ceramics,Ferroelectric
更新于2025-09-10 09:29:36
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Penta-AlN2 monolayer: A ferromagnetic insulator
摘要： A ferromagnetic insulating behavior is necessary to realize quantum anomalous Hall effect. Here we study, using first-principles calculations and a Monte Carlo simulation, the electronic structure and magnetism of AlN2 monolayer. Our results show that the AlN2 monolayer has a ferromagnetic insulating behavior. By using the crystal field analysis, we find that the axes of the neighboring N2 dimers are perpendicular, and the superexchange between them accounts for the ferromagnetic (FM) order in the AlN2 monolayer. We also carried out a Monte Carlo simulation, which shows that the AlN2 monolayer remains FM with Curie temperature (Tc) ~ 22 K. Moreover, the tensile strain would make a stronger overlap between the neighboring N2 dimers, and steadily enhances the FM stability. As a result, the Tc can be increased with the tensile strain.
关键词： tensile strain,ferromagnetic insulator,AlN2 monolayer,superexchange,quantum anomalous Hall effect
更新于2025-09-10 09:29:36
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Fabrication and Characterization of a Magnetized Metal-Encapsulated FBG Sensor for Structural Health Monitoring
摘要： A novel means of metal packaging of a fiber Bragg grating (FBG) sensor using stainless steel and tin, together with high temperature resistant samarium cobalt (SmCo) magnet is proposed in this paper. The inclusion of high temperature-capable SmCo magnets enable the metal packaging of the FBG sensor with magnetic capabilities. This packaged sensor can be placed in direct contact with the substrate structures such as iron pipelines and other ferromagnetic components without any adhesives, making them easily detachable and reusable. This is a significant improvement compared with other commercial fiber optic sensors which are, surface attached using epoxies or welded to the substrate. The design parameters and characteristic properties such as load, temperature, and vibration sensitivity of the magnetic metal-packaged FBG sensor are studied numerically and validated experimentally to demonstrate the feasibility of using the encapsulated reusable FBGs for structural health monitoring of compatible structures.
关键词： fiber Bragg gratings,welding,Acoustic emission sensors,temperature,strain
更新于2025-09-10 09:29:36
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Anisotropic Electron–Phonon Interactions in Angle-Resolved Raman Study of Strained Black Phosphorus
摘要： Few layer black phosphorus (BP) with in-plane puckered crystalline structure has attracted intense interest for strain engineering owing to both its significant anisotropy in mechanical and electrical properties as well its high intrinsic strain limit. Here we investigated the phonon response of few layer BP under uniaxial tensile strain (~7%) with in-situ polarized Raman spectroscopy. Together with the first-principles density functional theory (DFT) analysis, the anisotropic Poisson’s ratio in few-layer BP was verified as one of the primary factors that caused the large discrepancy in the trend of reported Raman frequency shift for strained BP, armchair (AC) direction in particular. By carefully including and excluding the anisotropic Poisson’s effect in the DFT emulations, we rebuilt both trends reported for Raman modes shift. Furthermore, the angle-resolved Raman spectroscopy was conducted in-situ under tensile strain for systematic investigation of the in-plane anisotropy of BP phonon response. The experimentally observed thickness and crystallographic orientation dependence is elaborated using DFT theory as strong correlation between the strain perturbated electronic band structure and the phonon vibration modes. This study provides insight, both experimentally and theoretically, for the complex electron-phonon interaction behavior in strained BP, which enables diverse possibilities for strain engineering of electrical and optical properties in BP and alike two-dimensional (2D) nano materials.
关键词： black phosphorus,anisotropic Poisson’s ratio,electron-phonon interactions,angle-resolved Raman spectroscopy,strain engineering
更新于2025-09-10 09:29:36
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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 - Viscoplastic Constitutive Model for High Strain Rate Mechanical Properties of SAC-Q Leadfree Solder After High-Temperature Prolonged Storage
摘要： Electronics in automotive underhood and downhole drilling applications may be subjected to sustained operation at high temperature in addition to high strain-rate loads. SAC solders used for second level interconnects have been shown to experience degradation in high strain-rate mechanical properties under sustained exposure to high temperatures. Industry search for solutions for resisting the high-temperature degradation of SAC solders has focused on the addition of dopants to the alloy. In this study, a doped SAC solder called SAC-Q solder have been studied. The high strain rate mechanical properties of SAC-Q solder have been studied under elevated temperatures up to 200°C. Samples with thermal aging at 50°C for up to 6-months have been used for measurements in uniaxial tensile tests. Measurements for SAC-Q have been compared to SAC105 and SAC305 for identical test conditions and sample geometry. Data from the SAC-Q measurements has been fit to the Anand Viscoplasticity model. In order to assess the predictive power of the model, the computed Anand parameters have been used to simulate the uniaxial tensile test and the model predictions compared with experimental data. Model predictions show good correlation with experimental measurements. The presented approach extends the Anand Model to include thermal aging effects.
关键词： SAC-Q solder,thermal aging,high strain rate,mechanical properties,Anand Viscoplasticity model
更新于2025-09-10 09:29:36
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Ultrawide strain-tuning of light emission from InGaAs nanomembranes
摘要： Single-crystal semiconductor nanomembranes provide unique opportunities for basic studies and device applications of strain engineering by virtue of mechanical properties analogous to those of flexible polymeric materials. Here, we investigate the radiative properties of nanomembranes based on InGaAs (one of the standard active materials for infrared diode lasers) under external mechanical stress. Photoluminescence measurements show that, by varying the applied stress, the InGaAs bandgap energy can be red-shifted by over 250 nm, leading to efficient strain-tunable light emission across the same spectral range. These mechanically stressed nanomembranes could therefore form the basis for actively tunable semiconductor lasers featuring ultrawide tunability of the output wavelength.
关键词： strain-tuning,nanomembranes,photoluminescence,light emission,InGaAs
更新于2025-09-10 09:29:36
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Formation of uniaxial strained Ge via control of dislocation alignment in Si/Ge heterostructures
摘要： Uniaxially strained Ge/SiGe heterostructures are fabricated by selective ion implantation technique, where dislocation alignments are highly controlled by the local defect introduction. Firstly, ion-implantation-defects are selectively induced into a Ge substrate, followed by the growth of a SiGe buffer layer. As a result, the SiGe on the implanted region is largely strain-relaxed due to the defects acting as dislocation sources. In contrast, it is demonstrated that anisotropic strain relaxation takes place in the SiGe on the unimplanted region, leading to the uniaxial strained SiGe. A strained Ge layer is pseudomorphically grown on the SiGe buffer and the same strain states are observed for the Ge layer. It is found that mis?t dislocations generated at the interface between the SiGe layer and the Ge substrate are aligned along only one direction. These one-directional dislocations are an origin of the uniaxial strain relaxation. Moreover, effects of ion-implantation stripe-pattern widths on the strain states are investigated. With the implanted line width increasing, the anisotropy of the strain in the unimplanted region is enhanced. From these results, it can be said that this technique opens a route to engineer dislocation alignments and anisotropic strain in semiconductor hetero structures toward high performance novel devices.
关键词： dislocation alignment,uniaxial strained Ge,Si/Ge heterostructures,selective ion implantation,anisotropic strain relaxation
更新于2025-09-10 09:29:36