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- 实验方案
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Self-assembled monolayer for polymer-semiconductor interface with improved interfacial thermal management
摘要： Reliability and lifespan of highly miniaturized and integrated devices will be effectively improved if excessive accumulated heat can be quickly transported to heat sinks. In this study, both molecular dynamics (MD) simulations and experiments were performed to demonstrate that self-assembled monolayers (SAMs) have high potential in interfacial thermal management and can enhance thermal transport across polystyrene (PS) / silicon (Si) interface, modelling the common polymer/semiconductor interfaces in actual devices. The influence of packing density and alkyl-chain length of SAMs are investigated. Firstly, MD simulations show that the interfacial thermal transport efficiency of SAM is higher with high packing density. The interfacial thermal conductance (ITC) between PS and Si can be improved up to 127 ± 9 MW m-2 K-1, close to the ITC across metal and semiconductor interface. At moderate packing density, the SAMs with less than 8 carbon atoms in alkyl-chain show superior improvements over those with more carbons due to the assembled structure variation. Secondly, time-domain thermoreflectance technique was employed to characterize the ITCs of a bunch of Al/PS/SAM/Si samples. C6-SAM enhances the ITC by 5 folds, from 11 ± 1 MW m-2 K-1 to 56 ± 17 MW m-2 K-1. The interfacial thermal management efficiency will weaken when alkyl-chain exceeds 8 carbon atoms, which agrees with the ITC trend from MD simulations at moderate packing density. The relationship between SAM morphology and interfacial thermal management efficiency is also discussed in detail. This study demonstrates the feasibility of molecular level design for interfacial thermal management from both theoretical calculation and experiment, and may provide a new idea for improving the heat dissipation efficiency of micro devices.
关键词： polymer/semiconductor interface,time-domain thermoreflectance,molecular dynamics simulation,self-assembled monolayer,interfacial thermal management
更新于2025-09-11 14:15:04
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Wearable SiPM-based NIRS Interface Integrated with Pulsed Laser Source
摘要： We present the design of a miniaturized probe integrating silicon photomultiplier and light-pulsing electronics in a single 2x2mm2 CMOS chip which includes functional blocks such as a fast pulse-laser driver and synchronized single-photon detection circuit. The photon pulses can be either counted on-chip or processed by an external high-speed electronic module such as time-corelated single photon counting (TCSPC) unit. The integrated circuit was assembled on a printed circuit board (PCB) and also on a 2.5D silicon interposer platform of size 1 cm and interfaced with a silicon photomultiplier (SiPM), vertical cavity surface emitting laser (VCSEL) and other ancillary components such as capacitors and resistors. Our approach of integrating an optical interface to optimize light collection on the small active area and light emission from the vertical-cavity surface-emitting laser (VSCEL) will facilitate clinical adoption in many applications and change the landscape of Near Infrared Spectroscopy (NIRS) hardware commercially due to significant optode-size reduction and the elimination of optical fibers.
关键词： Near-Infrared Spectroscopy (NIRS),Time-Domain (TD),complementary metal-oxide-semiconductor (CMOS),Vertical Cavity Surface Emitting Laser (VCSEL),Silicon Photomultiplier (SiPM),Optical Probe
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Femtosecond Laser Processing and Evaluation of Broadband THz Anti-Reflection Structures
摘要： We fabricate terahertz anti-reflection structures on the surface of high-resistivity silicon via femtosecond laser processing. We measure its spectral properties by terahertz time-domain spectroscopy, and find a broadband increase in transmissivity over 0.3 - 2.5 THz. We investigate the observed spectral characteristics of this transmission by using numerical simulation. We successfully reproduce the observed result for all frequencies, including a previously undocumented high-frequency drop-off, when the model includes additional material losses. We believe these effects to be induced by the laser-ablation fabrication process.
关键词： anti-reflection,high-resistivity silicon,femtosecond laser processing,terahertz time-domain spectroscopy,terahertz
更新于2025-09-11 14:15:04
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Parallel Simulation of Fully Coupled Electrothermal Processes in Large-Scale Phase-Change Memory Arrays
摘要： Numerical simulation of fully coupled electrothermal processes in phase-change memory (PCM) arrays is performed in this article. For realizing the ability in simulating the electrothermal responses of large-scale PCM arrays, an in-house parallel simulator based on domain decomposition method (DDM) and time-domain finite element method (FETD) is developed, with its performance evaluated in terms of accuracy and scalability. Then, thermal crosstalk in the PCM array is investigated using the developed simulator, and a diamond layer is introduced to suppress thermal crosstalk. Furthermore, the scaling effects of PCM arrays on their electrothermal performance are examined. A scheme for multibit PCM design is proposed, and the electrothermal characteristics of proposed 2-bit PCM cells and arrays are studied numerically.
关键词： phase-change memory (PCM),multibit PCM,parallel computing,time-domain finite element method (FETD),Electrothermal simulation,thermal crosstalk
更新于2025-09-11 14:15:04
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Thin-wall cyclic olefin copolymer tube waveguide for broadband terahertz transmission
摘要： A thin-wall cyclic olefin copolymer (COC) tube terahertz (THz) waveguide was proposed and fabricated for broadband terahertz transmission. A dynamic coating method was developed to prepare highly uniform COC tube waveguide samples with an inner diameter of 2.8 mm and three different wall thicknesses from 33.0 to 58.6 μm. The resonant frequencies and transmission bandwidths were measured by the THz time domain spectroscopy and proven to be adjustable by the wall thickness of the COC tube waveguides. The measured minimum losses of the waveguide sample with the wall thickness of 58.6 μm for the straight and bending transmissions are 0.10 dB/cm and 0.18 dB/cm at 1.05 THz, respectively.
关键词： Polymer tube waveguide,Terahertz time domain spectroscopy,Dynamic coating method,Terahertz transmission
更新于2025-09-11 14:15:04
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Metamaterials and Metasurfaces || Electron Beam-Induced Directional Terahertz Radiation from Metamaterials
摘要： We have numerically analyzed an electron beam (e-beam)-induced directional terahertz (THz) radiation from metamaterials. Here, we used metallic grating structures with graded depths, in which only one-way surface mode can be supported based on the spoof surface plasmon polariton (spoof SPP) concept and gives unique directional THz radiation. For numerical analysis, we used a simplified particle-in-cell (PIC) finite-difference time-domain (FDTD) method. First, we describe our simplified PIC-FDTD method in detail. Then, we show our results on the e-beam-induced directional THz radiation from graded grating with graded depths. By passing pulsed (bunched) e-beam along the grating surface, directional THz radiations are obtained from one side of the grating with shallower grooves. The direction of these radiations can be switched backward or forward by making the groove depth deeper or shallower. The spectra of these directional radiations are wide band and contain multiple sharp peaks. The deepest and the shallowest groove depths determine the lowest and the highest frequency of the radiation band, respectively. These unique radiation characteristics cannot be explained by the conventional Smith-Purcell radiation and should be attributed to the spoof SPP that originates from different locations on the graded grating.
关键词： graded grating,Smith-Purcell radiation,THz,particle-in-cell finite-difference time-domain,metamaterial,PIC-FDTD,electron beam,terahertz
更新于2025-09-11 14:15:04
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Influence of the Laser Frequency Drift in Phase-Sensitive Optical Time Domain Reflectometry
摘要： The influence of the laser frequency drift on the operation of phase-sensitive optical time domain reflectometry (?-OTDR) systems is considered. Theoretical results based on a new numerical ?-OTDR model demonstrating the influence of the laser frequency instability on a signal are reported. This model is verified based on experimental data. It has been used to calculate the signal-to-noise ratio (SNR) of the system for different parameters of the laser source stability. As a result, quantitative requirements for lasers used in ?-OTDR systems are formulated.
关键词： laser frequency fluctuation,phase-sensitive optical time domain reflectometer,narrow-band laser,distributed sensor
更新于2025-09-11 14:15:04
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Time-domain Formulation of a Multi-layer Plane Circuit Coupled with Lumped-parameter Circuits using Maxwell Equations
摘要： We calculate electromagnetic phenomena in the multi-layer plane circuit starting from the Maxwell equations. We present a numerical method of potential and current density in two-dimensional conductors, where their time developments are treated as phenomena of wave propagation. We treat the plane conductors by dividing them into small finite-volume elements, similar to the case of the partial element equivalent circuit method, and the transport equations are then solved by the finite-difference time-domain method. Furthermore, we develop a calculation method for the boundary in a multi-layer plane by applying the method we have used in multi-transmission lines. We formulate the boundary conditions of a multi-layer plane coupled with lumped-parameter circuits and introduce an algorithm to reduce calculation costs that are largely associated with the two-dimensional extension from the multi-transmission-line case. We perform calculations of the wave propagation of potential, current density, and charge density in the time domain for a simple plane circuit. these calculations are presented as supplementary materials of the present paper.
关键词： wave propagation,multi-layer plane circuit,electromagnetic phenomena,lumped-parameter circuits,potential and current density,numerical method,finite-difference time-domain method,Maxwell equations
更新于2025-09-11 14:15:04
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Improving the performance of nanostructure multifunctional graphene plasmonic logic gates utilizing coupled-mode theory
摘要： Nanostructure ring resonators are suitable devices for photonic integrated circuits. A nano-scale multifunctional logic device based on plasmon-induced transparency (PIT) is presented here. This device consists of a pair of hexagonal ring resonators coupled with two parallel metal–insulator–metal (MIM) waveguides. According to the coupled-mode theory, the appropriate detuning between the resonances wavelengths of two resonators acts as the key factor to achieve the PIT phenomenon. For this purpose, the PIT phenomenon for several metals utilized in MIM waveguides is studied. Also, graphene has been employed as the replacement for the metal under the hexagonal ring resonator and its parallel waveguides. However, the interaction of light with graphene as a 2D material is weak, by varying the dimensions of waveguides, rings, and their distances, and also, incident light wavelength and graphene chemical potential, we have achieved the desired couplings in the structure. Finite-difference-time-domain (FDTD) simulations confirm that “1” and “0” logic states which represent the high and low levels of the optical power can be achieved at the through and drop ports by changing the refractive index. It has been demonstrated that the proposed structure implements the function of logical operations including XOR and XNOR, simultaneously.
关键词： Logical operations,Nanostructure ring resonators,Plasmon-induced transparency,Finite-difference-time-domain,Graphene,Metal–insulator–metal waveguides
更新于2025-09-11 14:15:04
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Ionization dynamics through a Fano resonance: Time-domain interpretation of spectral amplitudes
摘要： We investigate a conjecture used in recent experiments to reconstruct the complete dynamics of Fano autoionization processes out of measured spectral amplitudes [Gruson et al., Science 354, 734 (2016); Beaulieu et al., Science 358, 1288 (2017); Busto et al., J. Phys. B: At. Mol. Opt. Phys. 51, 044002 (2018)]. The validity of the conjecture is established analytically within the formalism of Fano, and tested numerically on model atoms displaying adjustable autoionizing states. A general condition for which the conjecture is valid, beyond the Fano case, is then derived.
关键词： Fano resonance,time-domain interpretation,autoionization,spectral amplitudes
更新于2025-09-11 14:15:04