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Laser‐Assisted Strain Engineering of Thin Elastomer Films to Form Variable Wavy Substrates for Cell Culture
摘要： Endothelial and epithelial cells usually grow on a curved environment, at the surface of organs, which many techniques have tried to reproduce. Here a simple method is proposed to control curvature of the substrate. Prestrained thin elastomer films are treated by infrared laser irradiation in order to rigidify the surface of the film. Wrinkled morphologies are produced upon stress relaxation for irradiation doses above a critical value. Wrinkle wavelength and depth are controlled by the prestrain, the laser power, and the speed at which the laser scans the film surface. Stretching of elastomer substrates with a “sand clock”-width profile enables the generation of a stress gradient, which results in patterns of wrinkles with a depth gradient. Thus, different combinations of topography changes on the same substrate can be generated. The wavelength and the depth of the wrinkles, which have the characteristic values within a range of several tens of μm, can be dynamically regulated by the substrate reversible stretching. It is shown that these anisotropic features are efficient substrates to control polarization of cell shapes and orientation of their migration. With this approach a flexible tool is provided for a wide range of applications in cell biophysics studies.
关键词： cell curvotaxis,laser treatment,curvature,dynamic substrates,strain engineering
更新于2025-11-21 11:08:12
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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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Phase Transition in Two-dimensional Tellurene under Mechanical Strain Modulation
摘要： We carry out computational simulations based on density functional theory (DFT) to investigate different phases of two-dimensional (2-D) tellurene. These phases are classified by their characteristic space groups and symmetry elements. Correlations of these phases to the bulk crystalline tellurium structure are also illustrated. Our specific interests include mechanical property calculations for different phases and the possible phase transitions between them. Simulation results show that these 2-D Te phases have very different elastic moduli due to their different atomic bonding and relaxed structures. Moreover, compression along the in-plane directions facilitates the α → β phase transition, while in-plane tensile strains always make the α-phase more stable than the β-phase. However, the energy difference between the two phases is comparable to or even much smaller than the thermal energy kT, depending on the in-plane strain direction. We find that further increase of the tensile strain along the chain direction beyond a critical value, ca. 12%, may lead to a possible α → γ phase transition. As the tensile strain is above 15%, the γ-phase will be more stable than the α-phase, accompanied by a further reduced transition energy barrier.
关键词： phase transition,elastic modulus,Tellurene,strain engineering,density functional theory (DFT),2-D materials
更新于2025-09-23 15:22:29
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Strain Effect in Highly-Doped n-Type 3C-SiC-on-Glass Substrate for Mechanical Sensors and Mobility Enhancement
摘要： This work reports the strain effect on the electrical properties of highly doped n-type single crystalline cubic silicon carbide (3C-SiC) transferred onto a 6-inch glass substrate employing an anodic bonding technique. The experimental data shows high gauge factors of (cid:1)8.6 in longitudinal direction and 10.5 in transverse direction along the [100] orientation. The piezoresistive effect in the highly doped 3C-SiC film also exhibits an excellent linearity and consistent reproducibility after several bending cycles. The experimental result is in good agreement with the theoretical analysis based on the phenomenon of electron transfer between many valleys in the conduction band of n-type 3C-SiC. Our finding for the large gauge factor in n-type 3C-SiC coupled with the elimination of the current leak to the insulated substrate could pave the way for the development of single crystal SiC-on-glass based MEMS applications.
关键词： piezoresistance,wafer bonding,silicon carbide,MEMS,strain engineering
更新于2025-09-23 15:21:01
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Strained bubbles in van der Waals heterostructures as local emitters of photoluminescence with adjustable wavelength
摘要： The possibility to tailor photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDCs) using external factors such as strain, doping and external environment is of significant interest for optoelectronic applications. Strain in particular can be exploited as a means to continuously vary the bandgap. Micrometer-scale strain gradients were proposed for creating ‘artificial atoms’ that can utilize the so-called exciton funneling effect and work, for example, as exciton condensers. Here we describe room-temperature PL emitters that naturally occur whenever monolayer TMDC is deposited on an atomically flat substrate. These are hydrocarbon-filled bubbles which provide predictable, localized PL from well-separated submicron areas. Their emission energy is determined by the built-in strain controlled only by the substrate material, such that both the maximum strain and the strain profile are universal for all bubbles on a given substrate, i.e., independent of the bubble size. We show that for bubbles formed by monolayer MoS2, PL can be tuned between 1.72 to 1.81 eV by choosing bulk PtSe2, WS2, MoS2 or graphite as a substrate and its intensity is strongly enhanced by the funneling effect. Strong substrate-dependent quenching of the PL in areas of good contact between MoS2 and the substrate ensures localization of the luminescence to bubbles only; by employing optical reflectivity measurements we identify the mechanisms responsible for the quenching. Given the variety of available monolayer TMDCs and atomically flat substrates and the ease of creating such bubbles, our findings open a venue for making and studying the discussed light-emitting ‘artificial atoms’ that could be used in applications.
关键词： photoluminescence,exciton funneling,monolayer transition metal chalcogenides,excitons,strain engineering
更新于2025-09-19 17:15:36
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Study on electronic and optical properties of the twisted and strained MoS2/PtS2 heterogeneous interface
摘要： We report electronic and optical properties of the MoS2/PtS2 heterogeneous interfaces subject to various twisting angles based on the first principles simulation. In order to sustain the structural stability and avoid to have a large size cell, the optimized rotation angles of the MoS2/PtS2 heterogeneous interfaces are 19.1°, 30.0° and 40.9°. It is found from the first principle simulation that the absolute passband amplitude of the refractive index, extinction coefficient, reflectivity and absorption coefficient curves under 30.0° rotation angle are 6–12 times higher than 19.1° and 40.9° rotation angles of the MoS2/PtS2 heterogeneous interfaces. Moreover, under the 30.0° twisting angle, the absorption coefficient in the absorption spectrum can reach to or above 105/cm. The absorption spectrum has a red-shift and a broadening effect with the tensile strain, from roughly 700 nm (0% externally strain) to 1050 nm (5% externally strain). The prominent optical properties of MoS2/PtS2 heterogeneous interface under 30° rotation angle still exist after taking into consideration the spin-orbit coupling (SOC) effect. These results suggest that the MoS2/PtS2 heterogeneous interfaces will have great potential applications in tunable optoelectronic devices.
关键词： Twisting angle,Optical performance,Strain engineering,MoS2/PtS2 heterogeneous structure
更新于2025-09-19 17:15:36
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Strain Engineering Coupled with Optical Regulation towards High-sensitivity In2S3 Photodetector
摘要： Non-layered 2D materials possess intriguing properties, widening the scope of 2D libraries and promising considerable potential for applications in next-generation optoelectronics. However, due to the surface dangling bonds and weak light adsorption arising from atomically thin thickness, their photosensitivity is still limited. Herein, we achieve an ultrasensitive 2D In2S3 photodetector by adopting strain engineering coupled with optical regulation. A SiO2 nanograting array was introduced to construct strained morphology of 2D In2S3. This morphology induces charge localization and renders back-to-back built-in electric field array, which efficiently suppresses the dark current and separates the photo-excited carriers. Simultaneously, the SiO2 nanograting array realizes light management and improves the light harvesting. As a result, the device presents an ultralow dark current of 3.2 pA with a high signal-to-noise ratio up to 1.7 × 106. Especially, a prominent photoresponsivity of 1810 A/W, an excellent detectivity of 2.09 × 1015 Jones and a fast response speed of 0.41 ms are achieved. This work depicts an effective scheme to associate photonic/electronic properties manipulation for optoelectronic applications.
关键词： strain engineering,SiO2 nanograting,In2S3,optical regulation,photodetector,2D materials
更新于2025-09-19 17:13:59
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Theoretical Study of GaN/BP van der Waals Nanocomposites with Strain-Enhanced Electronic and Optical Properties for Optoelectronic Applications
摘要： Construction of van der Waals (vdW) nanocomposites can advance two-dimensional (2D) materials with desired properties and significantly widen their applications. Based on first-principles calculations, we verify that a gallium nitride/boron phosphide (GaN/BP) vdW nanocomposite is a direct-gap semiconductor with type-I band alignment. The nanocomposite shows significant optical properties in the visible and near-ultraviolet regions. Additionally, the bandgap, band edge positions, and optical absorption of the GaN/BP nanocomposite can be tuned by in-plane biaxial strains. A biaxial tensile strain with a strength of 3% can induce the type-II band alignment in the GaN/BP nanocomposite, which results in effective separation of the photo-generated charge carriers. Meanwhile, the application of biaxial strain can also significantly enhance the optical absorption of the GaN/BP nanocomposite in the near-infrared and visible regions. Furthermore, we show that the adjustment of interlayer coupling is also an effective way to modulate the electronic and optical properties of the GaN/BP nanocomposite. Our studies reveal the potential application of the GaN/BP nanocomposite in optoelectronic devices.
关键词： first-principles calculations,optical absorption,strain engineering,band structure,GaN/BP nanocomposite
更新于2025-09-16 10:30:52
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Recrystallization and activation of ultra-high-dose phosphorus-implanted silicon using multi-pulse nanosecond laser annealing
摘要： Highly phosphorus-doped silicon source/drains are investigated to improve the performance of N-type metal-oxide-semiconductor field-effect transistors by decreasing their resistance and imparting strain to their channels. To find effective high temperature annealing for the activation of phosphorus in the source/drains, we apply single- and multi-pulse nanosecond laser annealing on highly phosphorus-doped silicon. The microstructure, strain, and electrical properties of highly phosphorus-doped silicon before and after laser annealing are analyzed. Our results demonstrate that the defects in both the recrystallized silicon and the end of range are decreased with 600 mJ cm?2 10-pulse annealing while considerable increase in phosphorus activation is achieved.
关键词： nanosecond laser annealing,strain engineering,activation,phosphorus-doped silicon,recrystallization
更新于2025-09-16 10:30:52
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Precise stress control of inorganic perovskite films for carbon-based solar cells with an ultrahigh voltage of 1.622?V
摘要： All-inorganic cesium lead bromide (CsPbBr3) perovskite solar cell is one promising candidate to balance high efficiency and poor stability of organic-inorganic hybrid photovoltaics. The charge carrier transport can be maximized for high-efficiency devices through precise stress control during perovskite grain growth process to obtain high-quality full-bromine CsPbBr3 halide films. We present here the monolayer-aligned and large-grained CsPbBr3 perovskite films through precise control of crystallization temperature of PbBr2 film because the lattice volume is enlarged by 2.18 times during the phase conversion from PbBr2 to CsPbBr3, which helps to minimize residual-stress-induced grain boundaries and defect-induced charge recombination. Upon further interfacial modification by nitrogen doped carbon quantum dots, the hole transporting materials free, all-inorganic CsPbBr3 perovskite solar cell achieves a champion efficiency as high as 10.71% with an ultrahigh open-circuit voltage of 1.622 V. Moreover, the unencapsulated solar cell demonstrates remarkable long-term stability in 85% humidity in air atmosphere.
关键词： Stability,Strain engineering,Crystal growth,Cesium lead bromide,Charge recombination,Inorganic perovskite solar cell
更新于2025-09-12 10:27:22