Tunneling Effect Research Articles

Unveiling the Interlayer Interaction in a 1H/1T TaS2 van der Waals Heterostructure.

This study delves into the intriguing properties of the 1H/1T-TaS2 van der Waals heterostructure, focusing on the transparency of the 1H layer to the charge density wave of the underlying 1T layer. Despite the sizable interlayer separation and metallic nature of the 1H layer, positive bias voltages result in a pronounced superposition of the 1T charge density wave structure on the 1H layer. The conventional explanation relying on tunneling effects proves insufficient. Through a comprehensive investigation combining low-temperature scanning tunneling microscopy, scanning tunneling spectroscopy, non-contact atomic force microscopy, and first-principles calculations, we propose an alternative interpretation. The transparency effect arises from a weak yet substantial electronic coupling between the 1H and 1T layers, challenging prior understanding of the system. Our results highlight the critical role played by interlayer electronic interactions in van der Waals heterostructures to determine the final ground states of the systems.

Double barrier structure of Mo/AlN/Mo/AlN/Mo multilayer and its resonant tunneling effect

We prepare a symmetrical double barrier structure of Mo/AlN/Mo/AlN/Mo by using the reactive magnetron sputtering on a sapphire substrate and examine its resonant tunneling effect. Characterizations of multilayers demonstrate that the AlN (0002) aligns well along the Mo (110). Direct current-voltage (DC I–V) test finds significant negative differential resistance at room temperature around 0.7 and 0.9 V carrier energy and with peak-to-valley current ratios of about 1.1 and 1.2. The simulation using conventional transfer matrix method suggests good consistence between the designed structure, the quantized energy level and the switching voltage. The large signal DC model also fits the experimental I–V properties. Our work provides a new type of resonant tunneling device in room temperature.

Implicit Swept Volume SDF: Enabling Continuous Collision-Free Trajectory Generation for Arbitrary Shapes

In the field of trajectory generation for objects, ensuring continuous collision-free motion remains a huge challenge, especially for non-convex geometries and complex environments. Previous methods either oversimplify object shapes, which results in a sacrifice of feasible space or rely on discrete sampling, which suffers from the "tunnel effect". To address these limitations, we propose a novel hierarchical trajectory generation pipeline, which utilizes the Swept Volume Signed Distance Field (SVSDF) to guide trajectory optimization for Continuous Collision Avoidance (CCA). Our interdisciplinary approach, blending techniques from graphics and robotics, exhibits outstanding effectiveness in solving this problem. We formulate the computation of the SVSDF as a Generalized Semi-Infinite Programming model, and we solve for the numerical solutions at query points implicitly, thereby eliminating the need for explicit reconstruction of the surface. Our algorithm has been validated in a variety of complex scenarios and applies to robots of various dynamics, including both rigid and deformable shapes. It demonstrates exceptional universality and superior CCA performance compared to typical algorithms. The code will be released at https://github.com/ZJU-FAST-Lab/Implicit-SVSDF-Planner for the benefit of the community.

Quantitative analysis of interface heat transport at the Si3N4/SiO2 van-der Waals point contact

Si3N4 and SiO2 have been widely used in lithium batteries and optical devices. The high energy density brought by device integration makes the interfacial heat transport at the nano scale a hot spot. To optimize interfacial heat transfer, the roughness of the device surface is continuously reduced down to the nanometer. However, due to the limitation of spatial resolution, it is difficult to realize the measurement of thermal boundary resistance in the case of nanoscale contact by the existing measurement means. There is a great discrepancy between the measurement and simulation results, making the optimization of interfacial heat transfer lack of experimental verification. In this paper, the measurement of thermal boundary resistance of Si3N4/SiO2 interface at the nano-scale, was firstly realized by the optimized 3ω-SThM system. The effect of air tunnel on the heat transfer between real surfaces was also analyzed. The progress made so far provides an effective experimental tool to measure interfacial heat transport at nanoscale point contact.

Dirac fermions collimation in heterostructures based on tilted Dirac cone materials

This paper aims to theoretically analyze the behavior of Dirac fermions in a tilted Dirac cone material, particularly those interacting with a barrier potential. Our results show that the degree of tilt in the y-direction can lead to different collimations of Dirac fermion beams relative to the Fermi and confinement surfaces. We have highlighted a range of results, including the conical geometry by illustrating the active surfaces and their geometric parameters in reciprocal space. To study the transmission probability, we have conducted numerical analyses, considering various system configurations and different external and internal physical parameters to characterize the fermionic transport behavior in a proposed heterostructure. Additionally, we examined the transmission of Dirac fermions in relation to the refractive indices and refraction between the different media constituting the system, discussing the tunneling effect and the Klein paradox in relation to various physical parameters. Our findings lay the groundwork for the development of controllable electronic devices using Dirac fermion collimation, governed by the tilt parameter, enabling precise manipulation and enhanced functionality.

Quantum Tunneling Enhanced Hydrogen Desorption from Graphene Surface: Atomic versus Molecular Mechanism

Abstract We study the desorption mechanism of hydrogen isotopes from graphene surface using first-principles calculations, with focus on the effects of quantum tunneling. At low temperatures, quantum tunneling plays a dominant role in the desorption process of both hydrogen monomers and dimers. In the case of dimer desorption, two types of mechanisms, namely the traditional one-step desorption in the form of molecules (molecular mechanism), and the two-step desorption in the form of individual atoms (atomic mechanism) are studied and compared. For the ortho-dimers, the dominant desorption mechanism is found to switch from the molecular mechanism to the atomic mechanism above a critical temperature, which is respectively ~300 K and 200 K for H and D.

Klein tunneling and Fabry-Perot resonances in the α - T 3 bilayer with aligned stacking

This paper investigates the quantum tunneling effect on the α − T 3 bilayer with aligned stacking. An effective model is constructed to describe the properties around the triple band crossings for stacking with a vertical alignment of sites in the bilayer system. Focusing on these band crossings, it is found that while the energy spectrum remains gapless throughout, it is characterized by flat energy bands. Subsequently, the transmission coefficient, T, for Dirac quasi-electrons across a rectangular potential barrier is calculated, alongside the relationship between the transmission rate and the coupling parameter α. It is observed that super-tunnel phenomena occur at certain values of the quasiparticle energy, where the transmission is perfect regardless of the angle of incidence on the barrier, with α = 1. Furthermore, it is found that for a wide range of parameter values, the transmittance evolves monotonically and exponentially with increasing alpha. The paper also highlights the occurrence of the Klein paradox in the system, where quasiparticles approaching the barrier with zero-angle incidence exhibit ideal quantum transparency.

Structure and Optoelectronic Properties of Perovskite-like (PEA)2PbBr3Cl on AlN/Sapphire Substrate Heterostructure

This study presents the structure and optoelectronic properties of a perovskite-like (PEA)2PbBr3Cl material on an AlN/sapphire substrate heterostructure prepared using spin coating. The AlN/sapphire substrate comprised a 2 μm thick AlN epilayer on a sapphire wafer deposited via metal–organic chemical vapor deposition (MOCVD). The peak position of (PEA)2PbBr3Cl photoluminescence (PL) on the AlN/sapphire substrate heterostructure was 372 nm. The emission wavelength ranges of traditional lead halide perovskite light-emitting diodes are typically 410 to 780 nm, corresponding to the range of purple to deep red as the ratio of halide in the perovskite material changes. This indicates the potential for application as a UV perovskite light-emitting diode. In this study, we investigated the contact characteristics between Ag metal and the (PEA)2PbBr3Cl layer on an AlN/sapphire substrate heterostructure, which improved after annealing in an air environment due to the tunneling effect of the thermionic-field emission (TFE) mechanism.

Physicochemical Mechanics Instead of Transition State Theory.

This article initially reminds the basics of transition state theory (TST) and gives a textbook example illustrating the often-forgotten problems with TST-based description of reversible reactions. Then, we briefly describe a suggested by us approach called physicochemical mechanics. It was initially developed to describe both the rates and equilibria of chemical mass transport. Here, we show that the same classical mechanics-based approach is working for the kinetics of elementary mono-, bimolecular, and electrochemical reactions. Traditional assumptions regarding pseudoequilibrium for transition state formation are not necessary anymore. A simple interpretation of compensation and tunneling effects is given. The inversion zone for rate constants of strongly exothermic redox reactions is also explained.

Investigation of carbon black nanoparticle modified cementitious composites for sensing dynamic vibro-acousto signals

Current application of intrinsic piezoresistivity of cementitious materials filled with nano conductive substances is limited in sensing quasi-static signals featuring low-frequency and high-amplitude. Its self-sensing capacity for low-amplitude and high-frequency vibro-acousto signals is not fully investigated. In this study, different doses of carbon black nanoparticles (CBN) are added in cementitious materials and their conductivity is measured to find the percolation zone where the tunnelling effect dominates the conduction mechanism, followed by the characterization of their piezoresistivity. Consequently, impact forces and crack-related energy release, which generate dynamic signals in the range of vibrational and acoustic frequencies, are individually utilized to test the behaviour of such materials for sensing dynamic vibro-acousto signals. The results show that CBN-modified cementitious composites which show excellent piezoresistivity behaviour are capable of locally self-sensing dynamic signals as sensors. Comparing with piezoelectrical sensors, the developed sensor shows higher sensitivity to crack initiation.

Assessment of effective electrical conductivity in spherocylindrical carbon nanotube composites incorporating intrinsic properties of CNTs and interphase layer

This study introduces an analytical model using mean-field theory to estimate the effective electrical conductivity in composites of spherocylindrical carbon nanotubes (CNTs). The model adjusts the interphase layer's thickness and conductivity based on CNT concentration, affecting the electrical tunneling effect, and incorporates the properties of both CNTs and the interphase layer. Validated through detailed comparisons with experimental data, the model accurately predicts the electrical conductivities of polymer-CNT composites (PCNTs). Mean Squared Error analysis highlights its enhanced precision and superiority over traditional cylindrical CNT models. The model also explores how CNT dimensions, intrinsic conductivity, tunneling distance, potential barrier height, and variations in interphase thickness and conductivity influence electrical conductivity and percolation thresholds. This analytical model improves accuracy in predicting PCNT electrical conductivity and provides critical insights for designing and optimizing conductive polymer nanocomposites.

PULSE TUNNEL EFFECT: PROSPECTS FOR SCALING PHOTOCATALYSTS

The paper presents the results of the study of the synthesis and comparative analysis of film-ceramic composites based on functional ceramics obtained by various methods, including thermomechanochemical and sol-gel methods. The influence of activation of the obtained materials by the pulse tunnel effect on their structure and properties is analyzed. Data on the development of plants under composite films in comparison with the control are presented.

PULSE TUNNELING EFFECT. FEATURES INTERACTION WITH SUBSTANCE

The article discusses the phenomenon of pulsed tunneling effect and its application to various processes, including laser radiation generation and hydrogen production from water vapor. Various mechanisms of laser operation, in particular the CO2 laser, are considered, and it is assumed that the pulsed tunnel effect can explain their high efficiency. The interaction of the pulsed tunnel effect with matter and the possibility of its use to increase the efficiency of various processes, including the synthesis of environmentally friendly hydrogen, are analyzed.

Critical Examination of Gamow's Theory of Alpha Particle Decay

Gamow’s Theory of Alpha Particle Decay was initially formulated for a limited set of nuclei. In this study, the researchers extend the scope and assessed the applicability of the theory to a broader range of nuclides especially those with different proton and neutron compositions. Three objectives were formulated to undertake the research. The researcher utilized one-dimensional WKB approximation to calculate the probability of tunneling through the potential barrier, which is a simplification compared to other formulas. The Geiger-Nuttall law, which describes a dependence of the disintegration constant on the range of α-particles, was deduced using the Gamow theory describing the passage of the α-particles through the Coulomb barrier by the quantum mechanical tunneling effect. Ground-to-ground state α-transitions for α-active nuclides were analyzed based on their half-lives and their dependence on various factors. The study revealed that all α-active nuclides whose Z ranges between 70 to100 undergoes similar alpha decay processes.

INVESTIGATION OF THE INFLUENCE OF PULSED RADIATION GENERATED BY FUNCTIONAL CERAMICS BASED ON THE PRINCIPLE OF PTE ON THE CHARACTERISTICS OF THE CR2O3-SIO2-FE2O3-CAO-AL2O3-MGO-CUO SYSTEM

This work investigates methods for producing ceramic materials based on the Cr2O3-SiO2-Fe2O3-CaO-Al2O3-MgO-CuO system capable of generating modulated pulsed radiation in the far-infrared spectral region. The possibility of synthesizing such ceramics, in addition to helio-technology, using thermomechanical processing and mechanoactivation of the initial carbonates is considered. A comprehensive analysis of the structure and properties of the obtained materials using X-ray structural, electron microscopic analysis, and other methods has been carried out. It has been established that activation by pulsed infrared radiation generated by the principle of pulsed tunneling effect (PTE) leads to changes in the microstructure of the samples, accompanied by the formation of metastable phases at the interfaces and the generation of radiation.

Why frequent traffic accidents at highway tunnel exit? – An experimental analysis of the slack effect

This study analyzes the causes of frequent traffic accidents at the exit areas of highway tunnels. Vehicle experiments were conducted to collect data on the light environment, vehicle speed, and driver eye movement. The distribution patterns of the illumination, vehicle speed, and gaze location occupancy were analyzed, and highway tunnels of different lengths were compared. The tunnel exit area is divided into the transition, exit, and departure zones. It was observed that there was an obvious white-hole effect at the exit zone, with drastic changes in the light environment. The presence of abnormal acceleration behavior in the transition zone and decreased attention in the departure zone demonstrate the existence of psychological and physiological slack in drivers. Additionally, the tunnel length positively correlates to the slack effect, which is stronger in extra-long tunnels than in the short and medium tunnels. Multiple control scenarios were established and driving simulation experiments were conducted to further analyze the impact of the slack effect on the traffic safety. The experimental results demonstrated that the slack effect of the extra-long tunnels exhibited an evident lag which was still present after leaving the tunnel exit. The average vehicle speed and trajectory offset were larger and more discrete in the post-tunnel zone than on an ordinary open road. The speed of the curve in the post-tunnel zone is 5.1 % higher than that of the curve in the ordinary road, and the maximum trajectory offset is 54.3 % higher. Thus, this study reveals the slack effect at tunnel exits and explains the abnormal phenomenon of relatively good traffic environments but high traffic accident rates in the transition and departure zones of tunnel exits. These results present considerable practical significance for the safe operation of highway tunnels, particularly extra-long tunnels.

Dynamically tunable perfect absorption based on quantum plasmonic metal-insulator-metal mirror

Achieving perfect absorption in nanostructures plays a crucial role in applications such as photovoltaics, photoluminescence, and sensing. In recent years, a large number of scholars have devoted themselves to the research of metamaterial absorbers from microwave to optical frequencies. However, almost these absorbers are based on the resonant absorption resulting from strong electromagnetic coupling. In this study, we propose a dynamically tunable perfect absorber based on quantum plasmonic tunneling effect with nonelectromagnetic coupling in a metal–insulator–metal mirror, which has never been demonstrated before as far as we know. With the manipulation of tunneling current and tunneling damping via altering the external bias on the tunneling electrodes, the absorptivity of proposed absorber can be modulated at the Er:YAG laser wavelength (2940nm) with the modulation deep near 92%. Moreover, both the absorptivity and full width at half maximum of this absorber have strong robustness to the incidence angle. This ultra-thin perfect absorber, characterized by its rapid response, exceptional integration capabilities, robust tolerance to the incidence angle, and superior controllability, holds tremendous promise for a broad range of applications within the realm of infrared imaging and treatment.

Impact of diversity of top management team on firm's green innovation: Evidence from China

AbstractThe diversity of top management team can bring more resources and opportunities to the enterprise and contribute to its green strategy. This research focuses on the relationship between diversity of top management team and green innovation and further identifies internal influencing mechanism. We employ the number of green patents, ratio of green patents, and the ratio of green inventions to describe and measure firm's green innovation. It finds that the diversity of top management team could trigger strategic green innovation rather than substantive green innovation of enterprise. There are positive impacts of diversity of top management team on number of green patents and ratio of green patents. There is no evidence that diversity of top management team promotes the ratio of green inventions. Based on heterogeneity analysis, we further confirm that the results mentioned above only exist in those firms with high energy consumption and high pollution. Meanwhile, this research examines the influencing mechanism and finds that the diversity of top management team stimulates number of green patents and ratio of green patent through reducing tunneling effect and enhancing internal control.

Ground settlement and tunnel response due to twin-curved shield tunnelling in soft ground with small clear distance

Twin curved tunnels are often encountered in shield tunnelling, where significant complexities in densely exploited underground space are observed. In this study, the ground settlement and tunnel deformation due to twin-curved shield tunnelling in soft ground were investigated using numerical simulation and field monitoring. Different curvature radii of twin curved tunnels and subsequent effects of tunnel construction were considered to reveal the tunnelling effect on ground surface settlement and tunnel deformation. The results show that the settlement trough yields one offset towards inside of curved shield tunnelling. The location of settlement trough and maximum settlement were affected by curvature radius but except for the shape and width of settlement trough. Adjacent parallel twin-curved shield tunnelling could increase the offset of existing settlement trough and maximum settlement. Then, an empirical prediction of surface settlement trough due to twin-curved shield tunnelling with same tunnel diameters in soft clay was proposed, which was applicable to curvature radius less than 800 m. Finally, a minimum radius of 600 m of curvature tunnel was proposed in terms of allowable convergence deformation of tunnel. The result could provide guidance on safety evaluation for twin curved shield tunnelling construction.

Electrical conductivity of multifunctional cementitious composites reinforced by graphene derivatives: A finite element-based computational micromechanics model

Graphene derivatives (GDs) are known for their considerable conductivity and electron mobility, making them promising candidates for developing electrically conductive cementitious composites (CCs). Consequently, CCs reinforced with GDs (CRGDs) can serve a variety of applications in the construction industry. Despite several experimental studies on the conductivity of CRGDs, finite element (FE) models have rarely been developed to investigate the conductivity of CRGDs. Previous FE models primarily focused on one-dimensional fillers like carbon nanotubes within polymeric matrices, overlooking the distinctive anisotropic behaviour of GDs in cementitious matrices. This study introduces a computational micromechanics model (CMM), integrating the representative elementary volume (REV) concept with FE analysis, to investigate the electrical conductivity of CRGDs. This model is particularly noted for its computational efficiency, as it converts the problem dimensions from 3D to 2D while ensuring an acceptable degree of accuracy. The CMM captures the anisotropic conductivity of GDs and includes critical conductivity mechanisms such as conductive pathways, the tunnelling effect, and field emission. Subsequently, REV size sensitivity analysis is performed to ensure the statistical relevance of the REV, followed by the model's validation against experimental data from the literature. Afterwards, the model's sensitivity analysis clarifies how different parameters, including the constituent properties, influence prediction results. The sensitivity analysis results suggest that the aspect ratio of GDs has considerable impacts on the electrical conductivity and the percolation threshold of CRGDs. Ultimately, this study aims to provide insights into the optimization and design of electrically conductive CRGDs and lay the foundation for future research in this area.