- 标题
- 摘要
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- 实验方案
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Performance-Enhancing Selector via Symmetrical Multilayer Design
摘要： Two-terminal selectors with high nonlinearity, based on bidirectional threshold switching (TS) behaviors, are considered as a crucial element of crossbar integration for emerging nonvolatile memory and neuromorphic network. Although great efforts have been made to obtain various selectors, existing selectors cannot fully satisfy the rigorous standard of assorted memristive elements and it is in great demand to enhance the performance. Here, a new type of Ag/TaOx/TaOy/TaOx/Ag (x < y) selector based on homogeneous trilayered oxides is developed to attain the required parameters including bidirectional TS operation, a large selectivity of ≈1010, a high compliance current up to 1 mA, and ultralow switching voltages under 0.2 V. Tunable operation voltages can be realized by modulating the thickness of inserted TaOy. All-TaOx-based integrated 1S1R (one selector and one memristor) cells, prepared completely by magnetron sputtering and no need of a middle electrode, exhibit a nonlinear feature, which is quite characteristic for the crossbar devices, avoiding undesired crosstalk current issues. The tantalum-oxide-based homojunctions offer high insulation, low ion mobility, and rich interfaces, which is responsible for the modulation of Ag conductive filaments and corresponding high-performance cation-based selector. These findings might advance practical implementation of two-terminal selectors in emerging memories, especially resistive random access memories.
关键词： conductive filaments,1S1R,multilayers,threshold switching,TaOx,selector
更新于2025-09-23 15:23:52
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Prediction of Strong Piezoelectricity in 3R-MoS2 Multilayer Structures
摘要： We present the first calculation of piezoelectric constants of 3R-MoS2 which is one of three known polytypes of MoS2. We demonstrate that the 3R-MoS2 structure with 5 layers has the highest reported piezoelectric constant of all MoS2 multilayer structures. The maximum piezoelectric constant is approximately 13% above the monolayer value. Also 3R-MoS2 structures with 4 and 6 layers have a larger piezoelectric coefficient compared to monolayer MoS2. Results are obtained using the molecular dynamics computational package LAMMPS subject to room temperature simulations. Our results indicate strong potential for multilayer 3R-MoS2 structures in nanosensor and nanogenerator applications.
关键词： Piezoelectric coefficient,3R-MoS2,Multilayers,Molecular dynamics
更新于2025-09-23 15:21:21
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Investigation of laser damage of grating waveguide structures submitted to sub-picosecond pulses
摘要： Grating waveguide structures (GWS) are reflective diffractive optical elements that operate based on the combination of sub-wavelength gratings (periodic microstructures) integrated with planar waveguides. They can be used for high-power laser applications for pulse compression, spectral stabilization, wavelength multiplexing, as well as polarization shaping. In this work, we investigate the laser-damage resistance of GWS based on Ta2O5/SiO2 multilayers at pulse durations of 500 fs and wavelength of 1030 nm. We particularly study the influence of the material of the multilayer sequence, the designed grating structure, and the operational conditions (angle of incidence and polarization of the laser beam) on the laser-damage resistance of the GWS. Comparison of measurements to simulation of the electric-field distribution in the structure reveals a good correlation between laser-induced damage threshold (LIDT) values and electric-field enhancement in the structure. Based on this work, an optimized design has been defined to increase the LIDT of the GWS. An improvement of the LIDT of a factor 2 has been obtained.
关键词： Ta2O5/SiO2 multilayers,Grating waveguide structures,Electric-field distribution,Sub-picosecond pulses,Laser-damage resistance
更新于2025-09-23 15:21:01
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Rapid On-Chip Healing of Metal Thin Films
摘要： Self-healing behavior, the ability to autonomously counteract damage, is observed in some inorganic materials, and it has recently been extended to various artificial systems. In metals, healing usually requires thermal activation by a furnace treatment that stimulates damage repair. High temperature exposure, however, renders these routes incompatible with temperature-sensitive systems such as on-chip microelectronic components. In this work, designing Ni/Al multilayers as on-chip heat sources, a concept for on-demand healing of metal films that no longer relies on external annealing, is demonstrated. The process is based on harvesting a solitary self-sustained heat wave that is produced by a solid-state reaction in the heat source to weld cracks in different metal films. Healing is activated at room temperature with a remarkably small current input and in situ probing reveals a large conductance recovery up to 500 nm wide cracks within 1 ms, orders of magnitude faster than furnace-based approaches. Intrinsic heat source healing represents a unique concept for rapid on-chip healing of metal films that will provide new flexibility to prevent failure in inaccessible electronic systems: from implantable healthcare devices, to space probe instrumentation.
关键词： reactive multilayers,self-healing,intrinsic heat source,thin films
更新于2025-09-23 15:21:01
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Photonic transmission spectra in graphene-based Gaussian random multilayers
摘要： The light-matter interaction is a very active and attractive research field and it is the basis of the photonic devices based on the generation, processing and storage of photons. In this work, we theoretically study the propagation of electromagnetic waves in one-dimensional photonic crystals consisting of two different dielectric slabs (silicon dioxide and titanium dioxide) separated by graphene. The spatial arrangement of the slabs is periodic, but we introduce randomness by using a Gaussian distribution of thickness with a specific standard deviation σ. The well-known transfer-matrix method is used as the mathematical approach. Our main goals are to investigate how the presence of such randomness can change the light transmission spectra and the emergence of robust photonic band gaps. For a given angle of incidence, our numerical results show that the two lowest frequency bandgaps are insensitive to the influence of the Gaussian distribution. Those band gaps emerge from two different mechanisms: one is due to the presence of graphene, while the other is due to the Bragg’s scattering. A strong transmission dependence on the standard deviation σ is also observed in our numerical results. More interesting, for the transversal magnetic case (angle of incidence θ ? 60°) the system can be adjusted to present transmission coefficient near to 1 and work like a perfect transparent media, what is useful for technological applications.
关键词： Electromagnetic waves propagation,Light waves transmission,Graphene,Photonic crystals,Random multilayers
更新于2025-09-23 15:21:01
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How to Grow Fully (100) Oriented SiC/Si/SiC/Si Multi-Stack
摘要： This paper reports on the successful elaboration of fully (100) oriented SiC/Si/SiC/Si multi-stack using chemical vapor deposition. Si(100) heteroepitaxy on 3C-SiC(100) is identified as the critical step which is solved by pulse insertion of precursors during cooling. It lead to the roughening of the 3C-SiC surface which in turn lead to the quasi-exclusive nucleation of (100) oriented islands at the expanse of (110) ones. Subsequent Si epitaxy on such modified surface allows growing fully (100) oriented Si layer, as confirmed by structural characterization of the layers. The 3C-SiC grown on top of such Si(100) layer is again of (100) orientation, forming thus a fully (100) oriented stack. Due to the high lattice mismatch, each interface of the stack is characterized by a high density of crystalline defects which are shown to recombine along with thickness. Antiphase domains present inside the 3C-SiC seed are shown to have no detrimental influence on the Si layer quality. Without the surface modification step, the Si layers grown on 3C-SiC are always polycrystalline with a mixture of (110) and (100) orientations.
关键词： CVD,3C-SiC,surface modification,multilayers,Si heteroepitaxy
更新于2025-09-19 17:15:36
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Strain distribution in (InAs) ∕(InSb) multilayer: A first principles calculations
摘要： Using first principles calculations we unveil the interfacial strain relaxation in (wurtzite-InAs)n/(zinc-blend-InSb)m multilayer specimens. We have shown that the distribution of strain along the growth direction depends on the relative thickness of the segments of the multilayer. The observed result has been explained in view of the propagation of lattice deformation due to lattice mismatch between InAs and InSb. To the end we have demonstrated that the fine tuning of the strain with the thickness of layers can be exploited to vary the band gap along the length of the multilayer. The modulation of the band gap in a multilayer system finds various applications in designing optoelectronic devices.
关键词： Strain,First principles calculations,InAs/InSb,Multilayers,Density of states
更新于2025-09-19 17:15:36
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Beryllium-Based Multilayer Mirrors and Filters for the Extreme Ultraviolet Range
摘要： This paper presents the first results of systematic studies of beryllium as a material for multilayer mirrors (MLM) and transmission filters (TF) for the EUV spectral range. The objective for the study is the need for the increase in reflectivity and spectral resolution of MLMs for studying the Sun's corona. We investigated Mo/Be (working wavelength is 13.2 nm), Be/Al and Be/Si/Al (17.1 and 30.4 nm) multilayers, as well as free-standing Be films. It was shown that the Be-containing MLMs have significant advantage in reflectivity while their spectral pass-band is similar to beryllium-free MLMs. Observation of the MLMs in the course of 20 months has not revealed any significant decrease in the reflection coefficient. Effect of the silicon interlayers on reflectance of Be/Al MLM is explained. Investigation of a free-standing beryllium filter of the 160 nm thickness showed that its mechanical strength is approximately at the same level as that of the aluminum filter with the same thickness. There is also high stability of the transmittance.
关键词： Multilayers,Multilayer Design,X-ray Mirrors,Space Optics
更新于2025-09-19 17:15:36
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Existence Conditions of High-k Modes in Finite Hyperbolic Metamaterials
摘要： The capability to support optical waves with very large wave vectors (high-k) is one of the principle features of hyperbolic metamaterials (HMMs). These waves play the key role in HMM applications such as imaging and lifetime engineering. E?ective medium approximation (EMA) as widely used analytical method to predict HMMs behavior, has shortcomings in calculating high-k modes of practical structures. EMA is applicable to a subwavelength unit cell of implicitly in?nite periodic structures. Using conventional EMA, in the present paper, boundary e?ects and spatial dispersion are taken into consideration to properly compute the high-k modes of ?nite-thickness multilayer HMMs. Applying nonlocal homogenization to stacks of alternating metal-dielectric layers, the corresponding e?ective medium is examined as a high-k waveguide sandwiched between the substrate and an ambient superstrate. The developed theory enables us to recognize two types of bulk waves coined as short-range and long-range propagating modes. Number of such modes as well as their cuto? conditions are quanti?ed for the ?rst time. Validity of the developed theory is veri?ed both numerically by rigorous simulations of the multilayer structures with the transfer matrix method and experimentally by optical characterization of the HMMs in infrared regime.
关键词： subwavelength metal-dielectric multilayers,e?ective medium theory,high-k modes,hyperbolic metamaterials
更新于2025-09-19 17:15:36
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Macroscopic Alignment of Block Copolymers on Silicon Substrates by Laser Annealing
摘要： Laser annealing is a competitive alternative to conventional oven annealing of block copolymer (BCP) thin films enabling rapid acceleration and precise spatial control of the self-assembly process. Localized heating by a moving laser beam (zone annealing), taking advantage of steep temperature gradients, can additionally yield aligned morphologies. In its original implementation it was limited to specialized germanium-coated glass substrates, that absorb visible light and exhibit low-enough thermal conductivity to facilitate heating at relatively low irradiation power density. Here, we demonstrate a recent advance in laser zone annealing, which utilizes a powerful fiber-coupled near-IR laser source allowing rapid BCP annealing over a large area on conventional silicon wafers. The annealing coupled with photothermal shearing yields macroscopically-aligned BCP films which are used as templates for patterning metallic nanowires. We also report a facile method of transferring laser-annealed BCP films onto arbitrary surfaces. The transfer process allows patterning substrates with a highly corrugated surface and single-step rapid fabrication of multilayered nanomaterials with complex morphologies.
关键词： laser annealing,photothermal processing,block copolymers,nanopatterning,directed self-assembly,multilayers
更新于2025-09-19 17:13:59