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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) - Dynamical space partitioning for acceleration of parallelized lattice kinetic Monte Carlo simulations
摘要： A new dynamical space partitioning method is presented in a parallelized lattice kinetic Monte Carlo (kMC) simulator to overcome the loss of parallel efficiency found in other parallelized kMC simulators. The dynamical partitioning of the simulation cell allows better load balancing through all threads hence reducing time consuming events during the simulation. The new method is evaluated against both hypothetical and real cases. In both cases, minimal differences between serial and parallelized simulations are found. In real cases, other code optimizations may be needed to further improve the parallel efficiency.
关键词： shared memory,stochastic,nano-scale,FinFET,kMC,parallelization efficiency,OpenMP
更新于2025-09-23 15:22:29
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Multiple reflection assisted Laser Doppler Vibrometer setup for high resolution displacement measurement
摘要： An experimental design of high resolution non-intrusive displacement sensor working on the principle of basic LDV is being presented. Resolution enhancement has been achieved through phase multiplication using multiple reflections within a high-Q cavity created by a vibrating surface and a high reflection mirror placed parallel to each other. Displacement of 72 nm has been measured with an error range of ±14 nm through direct counting of characteristic peaks in ‘‘half cycle’’ of a interferogram. A linear relationship between displacement and number of reflections has been obtained which offers a straightforward route to measure displacements up to sub-nanometer scale and the resolution is essentially dictated by the reflectivity and physical dimension of moving source.
关键词： Sub-nano scale measurement,Interference,Laser Doppler Vibrometery
更新于2025-09-23 15:19:57
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Soft X-ray laser ablation for nano-scale chemical mapping microanalysis
摘要： Laser-assisted microanalysis offers the advantage of determining the spatially resolved compositions in 3D. Scanning a material with a sequence of sampling laser pulses and acquiring online the related spectra allow one to map the lateral and depth distribution of elements and molecules. However, the requirement to analyse smaller and smaller length-scales is challenged by focal diffraction as well as reduction of the nano-scale. Electron-based microprobes still offer unmatched spatial resolution. Disruptive improvements in laser technology are however demonstrated utilizing recently self-developed extreme ultraviolet or soft X-ray lasers. Firstly, a significant enhancement of the resolution is accomplished thanks to a much shorter wavelength, with respect to state-of-the-art commercial lasers. Furthermore, as the most innovative aspect, the sampling efficiency is enhanced using 'ionizing radiation', i.e. directly activating the target material. The high photon-energy (20–100 eV) makes the sampling process essentially single-photon, whatever bond or ionization energy. Furthermore, the analytical setup is simplified to a sampling source and detector, i.e. without the need for a secondary ionization or excitation source as in some state-of-the-art analytical systems. In this review, fundamental aspects of X-ray laser desorption and ablation are discussed, and a survey of the available literature is presented. The main objective is to convince the reader that desorption or ablation in this spectral domain is a significantly cleaner sampling process, with large potential, still requiring investigation for a complete fundamental understanding. Applications of laser microanalysis are thus entering the nano-scale era, which shrinks the gap with electron-based microprobes.
关键词： Laser-assisted microanalysis,XUV/SXR lasers,ablation,single-photon sampling,nano-scale chemical mapping,desorption
更新于2025-09-19 17:13:59
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Laser-assisted surface processing for functionalization of polymers on micro- and nano-scale
摘要： Rapid manufacturing of functionalized polymers enable a cost-ef?cient method for many applications in the biological, and medical sector. Laser structuring techniques differ for fast fabrication processes of thermoplastics. Here we report on direct UV laser ablation of polystyrene and polydimethylsiloxane to control wettability and bio-compatibility. For this purpose contact angle measurements and L929 cell growth experiments were performed as function of laser and process parameters. This work also describes the potential of laser-assisted hot embossing which has been introduced to replicate pre-fabricated micro- and nano-sized structures onto polymers proving it to be a cost-ef?cient and ?exible method for surface functionalization. Therefore, pre-fabricated laser-induced periodic surface structures have been manufactured as mould inserts using ultrafast laser radiation near the ablation threshold. These mould inserts can also be made of nickel, silicon or glass proving laser-assisted hot embossing to be a versatile tool for the functionalization of thermoplastics and meet the requirements for modern manufacturing with regard to quality and production ?exibility.
关键词： Bio-compatibility,Functionalization of polymers,Wettability,Laser-assisted surface processing,Laser-assisted hot embossing,Micro- and nano-scale
更新于2025-09-19 17:13:59
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Nano-scale wave dispersion beyond the First Brillouin Zone simulated with inertia gradient continua
摘要： Nano-scale wave dispersion beyond the First Brillouin Zone is often observed as descending branches and inflection points when plotting frequency or phase velocity against the wave number. Modeling this with discrete chain models is hampered by their restricted resolution. A continuum model equipped with higher-order inertia gradients is here developed as a suitable and versatile alternative. This model can be derived from discrete chain models, thereby providing a lower-scale motivation for the higher-order gradient terms. The derived gradient model is without free parameters, as the material constants are calculated a priori by minimising the error with respect to the discrete chain response. Unlike asymptotic approximations that provide a best fit for vanishing wave numbers, the error is here minimised over the entire range of reduced wave numbers 0 to 1, which leads to a much improved accuracy beyond the First Brillouin Zone. The new gradient model has been validated against (i) phonon dispersion curves measured through neutron scattering experiments in bismuth, aluminum, and nickel and (ii) Molecular Dynamics (MD) flexural wave propagation simulations of carbon nanotubes. The model captures all qualitative aspects of the experimental and MD dispersion curves without requiring a bespoke curve fitting procedure. With the exception of one set of MD results, the accuracy of the gradient model is very good.
关键词： Nano-scale wave dispersion,Molecular Dynamics,First Brillouin Zone,inertia gradient continua,carbon nanotubes,phonon dispersion curves
更新于2025-09-10 09:29:36
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Micro-nano scale imaging and the effect of annealing on the perpendicular structure of electrical-induced VO2 phase transition
摘要： It was research hotspot that how to lower the threshold switching voltage (Vth), especially for the perpendicular structure of electrical-induced VO2 insulator-metal phase transition (MIT). This structure can reduce the Vth to the orders of 10-1 V. In micro-nano scale, combined with results of resistance change versus temperature, X-ray photoelectron spectroscopy measurements and conductive atomic force microscope, we had confirmed that V3+ was an important factor for electrical-induced VO2 thin MIT. On the one hand, joule heating produced by conductive V3+ region induced the surrounding VO2 region phase transition. On the other hand, with the annealing time increased from 0 min to 2 min at 470℃ in H2/N2 mixture gases, V3+ contents increased, thin film surface conductive areas increased, thin film resistance decreased, and finally resulted in threshold switching voltage decreased. Our experimental results were consistent with theory analysis. However, when the annealing time was too long (≥3 min), VO2 thin film threshold switching behavior disappeared, and current was linearly increased with voltage.
关键词： Perpendicular structure of electrical-induced VO2 MIT,Annealing process,Micro-nano scale current mapping,perpendicular VO2 thin film structure,threshold switching voltage
更新于2025-09-09 09:28:46
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Modulation Mode Detection & Classification for in-Vivo Nano-Scale Communication Systems Operating in Terahertz Band
摘要： This work initiates the efforts to design an intelligent/cognitive nano receiver operating in Terahertz (THz) band. Specifically, we investigate two essential ingredients of an intelligent nano receiver—modulation mode detection (to differentiate between pulse based modulation and carrier based modulation), and modulation classification (to identify the exact modulation scheme in use). To implement modulation mode detection, we construct a binary hypothesis test in nano-receiver’s passband, and provide closed-form expressions for the two error probabilities. As for modulation classification, we aim to represent the received signal of interest by a Gaussian mixture model (GMM). This necessitates the explicit estimation of the THz channel impulse response, and its subsequent compensation (via deconvolution). We then learn the GMM parameters via Expectation-Maximization algorithm. We then do Gaussian approximation of each mixture density to compute symmetric Kullback-Leibler divergence in order to differentiate between various modulation schemes (i.e., M -ary phase shift keying, M -ary quadrature amplitude modulation). The simulation results on mode detection indicate that there exists a unique Pareto-optimal point (for both SNR and the decision threshold) where both error probabilities are minimized. The main takeaway message by the simulation results on modulation classification is that for a pre-specified probability of correct classification, higher SNR is required to correctly identify a higher order modulation scheme. On a broader note, this work should trigger the interest of the community in the design of intelligent/cognitive nano receivers (capable of performing various intelligent tasks, e.g., modulation prediction etc.).
关键词： nano-scale communication,Expectation-Maximization algorithm,Kullback-Leibler divergence,Gaussian mixture model (GMM),modulation classification,Terahertz (THz) band,modulation mode detection
更新于2025-09-09 09:28:46