Accepted
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Abstract +
This study aims to elucidate the influence of cobalt (Co) diffusion on the chemical vapor deposition (CVD) process of hydrogen-terminated diamond (100) surfaces, with a particular focus on the effects on dehydrogenation reactions and the adsorption behaviors of critical carbon-hydrogen (C-H) groups.Currently, pretreatment methods are commonly employed to remove cobalt from the substrate in order to mitigate its effects during diamond deposition. However, these methods tend to reduce the substrate's toughness and increase preparation costs. Moreover, even when cobalt is partially removed, some of it within the substrate can still diffuse to the film-substrate interface and into the diamond film during the deposition process, thereby compromising the quality of the diamond film.The primary objective of this study is to investigate, at the atomic scale, how cobalt atoms diffusing into the diamond substrate affect the key reactions during diamond growth—specifically, dehydrogenation and C-H group adsorption. Understanding these effects is crucial for developing strategies to mitigate cobalt's adverse impact on diamond deposition.Using first-principles calculations based on density functional theory (DFT), we constructed geometric models of single-crystal diamond and its (100) surface. Co atoms were introduced at various diffusion depths (ranging from the 2nd to the 5th layer beneath the diamond surface), and the surfaces were hydrogen-terminated to mimic experimental conditions.The Dmol3 module in Materials Studio was employed to simulate and analyze the energy barriers for dehydrogenation reactions and the adsorption energies of key C-H groups, which include CH, CH2, CH3.Transition state searches were performed to determine reaction pathways and energy profiles, while adsorption energies were calculated to assess the stability of C-H group binding at active sites.The presence of Co significantly elevated the energy barriers for dehydrogenation reactions.The magnitude of this increase was positively correlated with the projected distance (DCo-H) between surface H atoms and Co atoms.Additionally, while the number of layers separating Co from the surface also influenced the energy barrier, this effect was less pronounced compared to DCo-H.Co diffusion altered the adsorption energies of C-H groups, particularly increasing the adsorption energy of CH3—a pivotal group in diamond growth.This resulted in reduced adsorption efficiency of CH3, thereby degrading the quality of diamond deposition. The impact varied with Co's diffusion depth: at the 2nd layer, all C-H groups exhibited increased adsorption energies, indicating thermodynamic instability; at deeper layers (3rd to 5th), CH3 consistently showed higher adsorption energies compared to Co-free conditions, while CH and CH2 exhibited more complex behaviors with some layers showing decreased adsorption energies.Our findings provide crucial insights into the atomic-scale mechanisms by which cobalt affects diamond CVD.The significant elevation of dehydrogenation energy barriers and the altered adsorption behaviors of C-H groups, especially CH3, underscore the challenges in depositing high-quality diamond films on WC-Co substrates.These results guide the development of strategies to mitigate cobalt's adverse effects, such as through optimized substrate pretreatments or barrier layer insertions, ultimately enhancing diamond film quality on cobalt-containing substrates.
Abstract +
As Moore's Law faces limitations in scaling device physical dimensions and reducing computational power consumption, traditional silicon-based integrated circuit (IC) technologies, after half a century of success, are encountering unprecedented challenges. These limitations are especially apparent in emerging fields such as artificial intelligence, big data processing, and high-performance computing, where the demand for computational power and energy efficiency is growing. Therefore, the exploration of novel materials and hardware architectures is crucial to overcoming these challenges. Two-dimensional (2D) materials, with their unique physical properties such as the absence of dangling bonds, high carrier mobility, tunable band gaps, and high photonic responses, have emerged as ideal candidates for next-generation electronic devices and integrated circuits (ICs). Notably, 2D materials such as graphene, transition metal dichalcogenides (TMDs), and hexagonal boron nitride (h-BN) have demonstrated immense potential in electronics, optoelectronics, and flexible sensing applications.
This paper provides a comprehensive review of recent advancements in the application of 2D materials in integrated circuits, analyzing the challenges and solutions related to large-scale integration, device design, functional circuit modules, and three-dimensional integration. Through a detailed examination of the basic properties of 2D materials, their constituent functional devices, and multifunctional integrated circuits, this paper presents a series of innovative ideas and methodologies, showcasing the promising application prospects of 2D materials in future ICs.
The research methodology involves a detailed analysis of the physical properties of common 2D materials (such as graphene, TMDs, and h-BN) and explores typical application cases. It discusses how to utilize the excellent properties of these materials to fabricate high-performance single-function devices, integrated circuit modules, and 3D integrated chips. In particular, the paper focuses on solving the challenges related to large-scale growth, device integration, and interface engineering of 2D materials. By comparing the performance and applications of various materials, it reveals the unique advantages of 2D materials in the semiconductor industry and their potential in IC design.
Despite the outstanding performance of 2D materials in laboratory environments, significant challenges remain in practical applications, especially in large-scale production, device integration, and three-dimensional integration. Achieving high-quality, large-area growth of 2D materials, reducing interface defects, and improving device stability and reliability are still core issues that need to be addressed by both the research and industrial communities. However, with continuous advancements in 2D material fabrication techniques and optimization of integration processes, these challenges are gradually being overcome, and the application prospects of 2D materials are expanding.
This paper provides a comprehensive review of recent advancements in the application of 2D materials in integrated circuits, analyzing the challenges and solutions related to large-scale integration, device design, functional circuit modules, and three-dimensional integration. Through a detailed examination of the basic properties of 2D materials, their constituent functional devices, and multifunctional integrated circuits, this paper presents a series of innovative ideas and methodologies, showcasing the promising application prospects of 2D materials in future ICs.
The research methodology involves a detailed analysis of the physical properties of common 2D materials (such as graphene, TMDs, and h-BN) and explores typical application cases. It discusses how to utilize the excellent properties of these materials to fabricate high-performance single-function devices, integrated circuit modules, and 3D integrated chips. In particular, the paper focuses on solving the challenges related to large-scale growth, device integration, and interface engineering of 2D materials. By comparing the performance and applications of various materials, it reveals the unique advantages of 2D materials in the semiconductor industry and their potential in IC design.
Despite the outstanding performance of 2D materials in laboratory environments, significant challenges remain in practical applications, especially in large-scale production, device integration, and three-dimensional integration. Achieving high-quality, large-area growth of 2D materials, reducing interface defects, and improving device stability and reliability are still core issues that need to be addressed by both the research and industrial communities. However, with continuous advancements in 2D material fabrication techniques and optimization of integration processes, these challenges are gradually being overcome, and the application prospects of 2D materials are expanding.
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High-performance humidity sensors have received widespread attention for their wide use in healthcare, archaeology, electronic device manufacturing, etc., thus developing humidity sensors with wide sensing range, high response, narrow humidity hysteresis, fast response/recovery, and excellent stability are urgently needed. Humidity-sensitive materials are the core of humidity sensors. To obtain high-performance humidity sensors, humidity-sensitive materials should have high hydrophilicity, conductivity, and stability. Metal organic frameworks (MOFs) are promising humidity-sensitive materials due to their special characteristics, but often limited by the poor conductivity and hydrophilicity. Herein, a proton conduction enhanced CMC-Na/MOF-801/PPY (CMP) humidity-sensitive material was prepared through in-situ polymerization, and the corresponding humidity sensor was fabricated via drop-casting. The structure, functional groups, specific surface area, and element distribution of the CMP material were investigated by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N2 sorption isotherm, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The abundant hydrophilic groups and continuous hydrogen bond network lead to tight dependence of the proton conductivity and impedance of the sensing material on the humidity. The results show that the optimized CMP sensor is highly sensitive to humidity change with high response of 516.7 at 43% RH and 1.24×105 at 85% RH, narrow hysteresis of 1.9% RH, and short response/recovery time of 2.8 s and 1.2 s in the humidity range of 7–85% RH. Compared to reported MOFs-based humidity sensors, the CMP sensor exhibits unique technical characteristics. Further, the humidity sensing mechanism of the CMP sensor was investigated through a combination of material characterization, water adsorption kinetics, carrier concentration, complex impedance spectroscopy (CIS) plot, and equivalent circuit (EC). As proof of concept, by monitoring the humidity on the finger surface, we evaluated the potential applications of the CMP sensor in noncontact sensing. Moreover, a palmar hyperhidrosis diagnosis system based on the CMP sensor was assembled, realizing quick, intuitive, and accurate diagnosis the severity of palmar hyperhidrosis. It is believed that this work provides a reasonable strategy for constructing high-performance humidity sensors.
, , Received Date: 2025-08-07
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Metasurface holography based on planar optical devices has attracted considerable attention due to its potential for miniaturizing optical components and systems. However, traditional on-axis holography has inherent zeroth-order diffraction and twin-image effects, which significantly degrade image quality and limit its practical applications. Off-axis metasurface holography, in contrast, provides a promising solution to overcoming these limitations. In this work, we design a metasurface hologram composed of titanium dioxide (TiO2) nanopillars on a silicon dioxide (SiO2) substrate,by using the high refractive index and low optical loss of TiO2 in the visible light range to achieve efficient phase control. The unit cell height is set to 600 nm to ensure sufficient phase accumulation, and the working wavelength is 635 nm. The hologram is constructed by mapping the continuous 0–2π phase distribution obtained from computational holography onto the unit cell array, and changing the nanopillar diameter to achieve full phase coverage. We systematically investigate the effect of the unit cell period on the imaging position in off-axis holography. Numerical simulations show that as the period increases from 280 nm to 350 nm, the center of the holographic image gradually shifts toward the center of the image plane. The optimal period is found to be 324 nm, at which the image is reconstructed precisely at the designed position. Further simulations using different off-axis angles (0°–45°) and nanopillar heights (600–2000 nm) confirm that the imaging position remains fixed at the target location, indicating that it is mainly determined by the unit cell period rather than other structural parameters. These results demonstrate that by carefully selecting the unit cell period, the holographic image can be accurately reconstructed at a predetermined positions with high image quality, providing theoretical guidance for designing high-precision off-axis metasurface holographic imaging systems.
, , Received Date: 2025-08-21
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Gold nanorods (AuNRs) have become highly promising biomedical probes due to their tunable plasmonic properties, but their real-time, high-resolution imaging of subcellular behavior, particularly their orientation dynamics reflecting critical nano-bio interactions, is hindered by the diffraction limits and drawbacks of existing super-resolution methods, such as reliance on high-intensity lasers and exogenous labeling. To solve this problem, we develop coherent modulation amplitude projection imaging (CMAPI), a novel label-free technique that uses spatially and temporally modulated pairs of femtosecond pulses to coherently control the two-photon photoluminescence (TPPL) of AuNRs. By using AuNRs as three-level systems with a measurable intermediate state, CMAPI encodes sub-diffraction-limit spatial and orientational information into the frequency domain through precise manipulation of inter-pulse delay, phase, and polarization. Experimental results confirm the nonlinear excitation nature of AuNRs, with single-pulse polarization response following a cos2θ dependence. Under two-pulse excitation, the emission exhibits obvious coherence-dependent behavior: at zero delay, the response is controlled by quantum superposition; under a delay that matches the intermediate state lifetime (0.5 ps), the three-level model accurately describes the response; under a longer delays (10 ps), the system returns to incoherent emission. CMAPI retrieves nanoscale information through Fourier analysis of photon arrival times, producing simultaneous amplitude and phase images that reveal AuNRs’ precise positions (about 60 nm localization precision), in-plane orientations (e.g. quadrant-specific arrangement inferred from phase sign), and local environmental coupling, such as plasmon-induced phase jumps, all under ultralow excitation power (<5 μW/μm2) to avoid light damage. This approach enables visualization of features beyond the diffraction limit, distinguishing multiple AuNRs within a single diffractive spot, as validated by scanning electron microscopy. CMAPI provides a powerful, non-invasive platform for quantifying dynamic biological processes involving anisotropic nanoparticles. These process include conformational shifts during endocytosis, torque transmission in molecular motors, and real-time tracking of nanoscale interactions, thereby offering profound insights into theranostic probe design and fundamental biophysical research.
, , Received Date: 2025-08-29
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, , Received Date: 2025-08-08
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Multiphoton microscopy (MPM) has become an essential research tool in biomedicine. Current MPM systems predominantly rely on Ti:sapphire lasers provided tunable femtosecond pulses at 720–950 nm. To access the second biological transparency window (1000–1350 nm), complex optical parametric oscillators are typically required. urthermore, sources operating in the third biological transparency window (1600–1750 nm) are attracting significant attention for enhanced imaging depth. However, no ultrafast laser source simultaneously covering all three transparency windows exists, thus hindering the widespread application of MPM in life sciences. Here, we demonstrate a fiber-laser-based ultrafast source that generates four-color tunable pulses across 800–1650 nm, covering the full spectral range for multiphoton excitation. This source utilizes our proposed spectral selection technique via self-phase modulation (SESS). SESS ensures SPM-dominated spectral broadening, producing isolated spectral lobes. Filtering the outermost lobes will generate near-transform-limited pulses with broad wavelength tunability. Using this supercontinuum excitation source, we successfully realize label-free imaging of diverse biomedical specimens, validating the performance of MPM empowered by this novel driving source.
, , Received Date: 2025-08-06
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In order to better understand and predict the complex interface instability phenomena induced by non-uniform shock waves in practical engineering and scientific applications, a detailed investigation has been conducted on the interaction between a Mach reflection wave configuration and a planar gas interface. Particular attention is paid to the role of the Mach stem scale in governing the evolution of interface instability and the associated mechanisms of perturbation growth. Numerical simulations show that when the Mach reflection wave configuration interacts with the interface, the complex wave structures impart initial velocity perturbations onto the interface, thereby triggering instability. This process is further influenced by the non-uniform post-shock flow field, under which the initially perturbed interface gradually evolves into a concave cavity and subsequently into jet-like bubble structures. These patterns are notably different from the spike and bubble morphologies observed in classical Richtmyer-Meshkov instability. A systematic quantitative analysis of the perturbation amplitude reveals that the instability growth can be divided into two different stages: an initial linear growth stage and a nonlinear development stage. The transition between these stages is governed by interface deformation mechanisms, particularly the bending of the slip line intersecting the interface and the subsequent formation of the curl-up jet. When the shock strength and incidence angle of the Mach reflection configuration are kept constant, the Mach stem scale emerges as the decisive parameter controlling the characteristic time of slip line curling and jet development. The results show that during the linear stage, perturbation growth is primarily determined by shock strength and incidence angle, and is insensitive to the Mach stem scale. In contrast, during the nonlinear stage, the perturbation growth rate increases with the augmentation of Mach stem scales, highlighting the scale-dependent nature of the nonlinear stage. Furthermore, theoretical models are critically examined against numerical simulation results. While existing models can reasonably capture the initial velocity perturbations imprinted on the interface by the Mach reflection configuration, they are unable to combine the effects of Mach stem scale and the sustained driving influence of post-shock flow non-uniformities. This limitation underscores the need for improved theoretical descriptions. Overall, these findings provide new insights into the intrinsic coupling among shock strength, incidence angle, and Mach stem scale in determining the evolution of shock-induced interface instability. These insights not only deepen the fundamental understanding of Richtmyer-Meshkov-type instabilities in non-classical regimes but also provide valuable references for the development of predictive theoretical models and also for engineering applications such as inertial confinement fusion and high-speed propulsion systems.
, , Received Date: 2025-08-05
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In radio-frequency capacitively coupled dusty plasma discharge, the grooves on the lower electrode plate significantly modify the electric potential distribution in the sheath region, thereby influencing the collective dynamic behavior of dust particles. Experimentally, when micrometer-sized dust particles are injected into the discharge chamber, a distinct layer of dust particles forms above the groove-induced potential well, exhibiting a characteristic bowl-shaped cloud structure. The volume of the dust cloud shows a strong dependence on RF power and discharge pressure. As power increases or pressure decreases, the dust cloud moves upward due to the influence of axial force on the particles. Besides, dust voids form in the middle of each dust layer, and their diameter evolution is influenced by particle number, RF power, and pressure. Particularly, when the diameters of the electrode grooves are small, the diameters of the dust voids first increase, then decrease and finally disappear as discharge pressure increases. Furthermore, a three-dimensional hybrid model is theoretically established. This model couples a fluid model with a dust particle model to explain the collective behavior of dust particles. This behavior is governed by the resultant axial force which includes axial electric field force, ion drag force, and gravity, as well as the resultant radial force, which consides radial electric field force and ion drag force. It is also found that in the DC-overlapped RF plasma, the suspension height of dust particles first increases and then decreases as the negative DC bias is increased. The change in dust particle height can reflect the transition of plasma discharge from α-model to γ- mode.
, , Received Date: 2025-08-25
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, , Received Date: 2025-08-22
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The liquid phase serves as a critical environment for chemical and biological reactions. The chemical and biological reaction dynamics of molecules in liquids exhibit evolution behaviors that are significantly different from those of isolated molecules in the gas phase. The in-depth investigation of the ultrafast excited-state dynamics of liquid-phase molecules is of great importance for uncovering the microscopic mechanisms underlying complex chemical and biological processes. Photoelectron spectroscopy not only reveals the electronic structure of excited-state molecules but also exhibits high sensitivity to structural changes, making it a powerful tool for studying the relaxation dynamics. Liquid-phase time-resolved photoelectron spectroscopy utilizes a liquid microjet within a high vacuum. In this pump-probe technique, an initial pump pulse excites the liquids to initiate dynamics, followed by a delayed probe pulse that ionizes the evolving system. The time-dependent energy distribution of the resulting photoelectrons, which encodes the ultrafast dynamics, is measured by a magnetic-bottle time-of-flight (TOF) analyzer. This review systematically summarizes recent advancements in the time-resolved liquid-phase photoelectron spectroscopy technology for studying ultrafast dynamics in liquids, detailing the fundamental working principles of magnetic-bottle spectrometers and the preparation techniques for liquid microjet targets. Furthermore, typical applications are discussed, concluding with an analysis of current technical challenges and future research directions.
, , Received Date: 2025-08-19
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Luminescence and anisotropy in two-dimensional (2D) materials have important implications for both fundamental material physics and potential applications such as polarized light-emitting devices. However, many natural-occuring 2D materials typically exhibit either luminescence or anisotropy, but not both. In this work, we utilize van der Waals (vdW) engineering to construct a heterostructure (HS) with anisotropic luminescent properties, which is composed of isotropic monolayer (1L) MoS2 (with strong intrinsic luminescence) and low-symmetry NbIrTe4 (strong anisotropy without photoluminescence). Experimentally, we characterize the optical response of the HS by using angle-resolved PL spectroscopy. The results indicate that the intrinsic anisotropic potential field of NbIrTe4 at the interface effectively breaks the in-plane isotropic symmetry of MoS2, inducing a pronounced polarization-dependent emission of A and B excitons. The anisotropy ratio is enhanced to ~1.58, corresponding to a linear polarization degree of approximately 22%. This work provides new insights into 2D interfacial coupling and offers useful guidance for the design and engineering of next-generation high-performance, tunable polarized light-emitting devices.
, , Received Date: 2025-08-09
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Owing to, Solid-state batteries have gradually become the focus of people's attention and research in recent years due to the advantages of high energy density and high safety factor. Lithium dendrites are a key factor affecting battery safety and service life, and in severe cases, battery short circuits can occur. Compared with liquid batteries, solid-state batteries rely on solid-state electrolytes with higher mechanical strength, which can effectively inhibit the growth of lithium dendrites, but with the increase of the number of charge-discharge cycles, the dead lithium produced by the incomplete dissolution of lithium dendrites gradually accumulates, and the performance of the battery gradually decreases. In this work, the problem of dead lithium in solid-state batteries is studied by using COMSOL Multiphysics 6.2 finite element simulation software. Due to the fact that existing research on dead lithium mainly focuses on phase field models combined with binary physics, there is little research on the influence of electrochemical parameters on dead lithium. Therefore, the phase field method is used to simulate the dissolution of lithium dendrites and the formation of dead lithium under the coupling of force-thermal-electrochemical fields. When the heat transfer model is coupled, the difference in the morphology of dead lithium before and after the coupled heat transfer model is further studied by applying an external pressure to change the stress of lithium dendrites. When the coupled mechanical field changes, the morphology of dead lithium before and after the coupled mechanical field is further studied by changing the temperature magnitude. At the same time, the effects of changes in three electrochemical parameters, namely diffusion coefficient, interfacial mobility and anisotropic strength, on the area of dead lithium are also explored. The research results indicate that when the heat transfer model or mechanical field is coupled into the phase field model, the dendrite dissolution cut-off time and dead lithium area will change. When the base rises at high temperature or when low external pressure or high external pressure is applied, the area of dead lithium decreases. For changing the electrochemical parameters, reducing the diffusion coefficient, increasing the interfacial mobility and reducing the anisotropic strength can effectively reduce the area of dead lithium.
, , Received Date: 2025-09-08
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The charge transfer cross sections of collisions between He ions in the solar wind and H2O molecule constitute essential data required for the astrophysical plasma modeling. However, experimental measurements of single charge transfer (SCT) cross sections for He+-H2O collisions at low-to-intermediate energies (corresponding to the velocity range of the solar wind) are extremely scarce, and first-priciple theoretical calculations have not been conducted. In this study, employing the time-dependent density functional theory nonadiabatically coupled with the molecular dynamics, the SCT cross sections are calculated for He+-H2O collisions over a broad energy range of 1.33–1800 keV. An inverse collision framework is used to investigate the charge transfer dynamics and electron-ion coupling processes. It is found that the SCT cross section exhibits a strong dependence on the molecular orientation. Furthermore, there are significant differences in the contributions of different molecular orientations to the cross section between low-energy and high-energy regions. The computed cross section results show good agreement with the existing data obtained from experiments and classical theoretical models. This indicates that the present theoretical method and numerical framework are not only applicable to handling the charge transfer processes in collisions between dressed ions and molecules but also enable the quantitative analysis of the effect of molecular orientation on the cross section. This study lays a foundation for cross section calculations of complex collision systems. The datasets presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00213.00193 .
, , Received Date: 2025-09-01
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The virtual cathode is an important phenomenon in thermionic emission, and it is widely present in various electronic devices and systems such as vacuum tubes, electron guns, high-power microscopes, X-ray tubes, concentrated solar thermionic converters, and emissive probes. Since the virtual cathode can directly affect the performance of these devices, it is of great significance to study the characteristics of the virtual cathode and conduct experimental measurements on it. In our recent research, a one-dimensional model of thermionic emission was established, and the analytical expressions for the potential barrier and the spatial width of the virtual cathode were derived. With the development of virtual cathode theories, measuring the virtual cathode experimentally has become a reality. In this study, based on our one-dimensional theoretical model, the absolute error theory of the virtual cathode is established, and the contributions of different parameters, such as the hot-cathode temperature, the saturated electron emission current, the electron collection current, Dushman constant, and the work function of hot cathodes, to the absolute errors in the virtual cathode measurement are systematically analyzed. The research results show that the main factors affecting the measurement of the virtual cathode potential are closely related to the size of the virtual cathode. When the virtual cathode potential generated by hot-cathodes is strong, the uncertainty of the hot-cathode temperature becomes the main error source, with a probability of about 61% for the potential barrier measurement, but when the virtual cathode is weak, the main factor becomes the uncertainty of the electron current measurement with a probability of about 39%. Besides, when measuring the virtual cathode width, for common hot-cathodes such as oxide (BaO) cathode, tungsten cathode, and molybdenum cathode, the main factors affecting the measurement results are the uncertainties in the hot-cathode temperature and the work function. These uncertainties account for approximately 94%, 96% and 97% of the measurement variability, corresponding to the above three cathodes, respectively. Only when the virtual cathode is very weak, does the uncertainty of the electron current become the main error source for the measurement of the virtual cathode width.
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