One-dimensional Device Research Articles

The modeling of acoustic black hole beam by spectral element method

A technique developed in recent decades for the passive control of vibrations and noise is the Acoustic Black Hole (ABH). The structural ABH effect is achieved by incorporating a local modification in the thickness of a thin structure, typically a beam or a plate, with a variation in thickness according to a spatial power law. The combination of the variation in the thickness power law and a local increase in damping, provided by the concomitant application of layers of viscoelastic material, produces a significant reduction in the wave propagation speed and an increase of attenuation properties. As an elastic wave propagates within an ABH, its propagation speed decreases smoothly and continuously, in theoretical case, when the structure's thickness disappears at the end of the ABH, the wave speed drops to zero. For practical applications, ABH is typically combined with dissipative materials to obtain significantly higher structural loss factors. This work aims to establish a numerical approach for modeling and designing a beam-type structural one-dimensional ABH device for vibration control device using the Spectral Element Method (SEM) and verified by the Finite Element Method (FEM). Examples are performed, and the results are compared with those found in the literature.

Electromechanical properties and piezoelectric potentials of one-dimensional GaN nanostructures: A bond relaxation investigation

From the viewpoint of atomic bond relaxation, an analytical approach was put forward to elucidate the physical origins of crystal size and cross-sectional shape dependency of piezoelectric potentials in GaN nanowires and nanotubes. It is demonstrated that (i) size-induced increase in piezoelectric potential is attributed to the coupling effect of the rising piezoelectric coefficient and both the reducing dielectric constant and elastic constant caused by the surface atomic coordination number loss, bond energy perturbation, and surface-to-volume ratio rising; (ii) as the number of sides for polygonal nanowires or nanotubes with the same equivalent radius decreases, the surface-to-volume ratio rises, and the piezoelectric potential increases; and (iii) the nanotubes can generate a piezoelectric potential higher than their nanowire counterparts due to their larger surface-to-volume ratios. The proposed formulation offers a scientific basis for the fabrication, optimization, and modulation of one-dimensional GaN-based piezoelectric nanometer devices.

Inverse design of ultrawideband one-dimensional metamaterial photonic filters using Riccati equation constrained gradient descent

One-dimensional photonic wave devices exhibit a pivotal role in wave engineering. Despite their relative simplicity, designing 1D wave devices that implement complex functionalities over a broad frequency range is challenging and requires careful sculpting and multiple optimizations. This paper theoretically and experimentally demonstrates a new inverse design paradigm to achieve a desired broadband frequency response efficiently. Specifically, we calculate the required dielectric profile along the device using constrained gradient descent optimization to minimize the L2 norm between the desired and actual responses. In each optimization step, we avoid the need to solve the complete set of Maxwell equations by using Riccati’s equation or its discrete ancestor as the optimization constraint for calculating the local reflection coefficient. Using this approach, we design several unorthodox filters, such as dual-band narrowband bandpass filters located within a wideband bandstop and ultrawideband first and second-order differentiators. The technique produces excellent results for ultrawideband frequency ranges, with very low computational complexity and, remarkably, with a single trivial guess for the optimization starting point. We experimentally implemented the two differentiator designs in radio frequencies using electronic circuit elements that comprise a metamaterial transmission line structure.

Realization of skyrmion shift register

The big data explosion demands novel data storage technology. Among many different approaches, solitonic racetrack memory devices hold great promise for accommodating nonvolatile and low-power functionalities. As representative topological solitons, magnetic skyrmions are envisioned as potential information carriers for efficient information processing. While their advantages as memory and logic elements have been vastly exploited from theoretical perspectives, the corresponding experimental efforts are rather limited. These challenges, which are key to versatile skyrmionic devices, will be studied in this work. Through patterning concaved surface topography with designed arrays of indentations on standard Si/SiO2 substrates, we demonstrate that the resultant non-flat energy landscape could lead to the formation of hexagonal and square skyrmion lattices in Ta/CoFeB/MgO multilayers. Based on these films, one-dimensional racetrack devices are subsequently fabricated, in which a long-distance deterministic shifting of skyrmions between neighboring indentations is achieved at room temperature. Through separating the word line and the bit line, a prototype shift register device, which can sequentially generate and precisely shift complex skyrmionic data strings, is presented. The deterministic writing and long-distance shifting of skyrmionic bits can find potential applications in transformative skyrmionic memory, logic as well as the in-memory computing devices.

Ultrafast laser inscription of 2D confinement MMI-based beam splitters with tunable splitting ratio in Nd:YAG crystal

The multimode-interference (MMI) devices based on the principle of self-imaging show great potential for applications in different scenarios. The research interest in two-dimensional confinement MMI devices has surged enormously due to the broader areas of applications compared with the one-dimensional confinement MMI devices. In this paper, we report on the characteristics of two-dimensional confinement 2 × 2 output MMI-based beam splitters which were achieved by femtosecond laser direct writing technology in a Nd:YAG crystal. The propagation features with different splitting ratios have been simulated by the beam propagation method. Two splitters with beam division performances of 2 × 2 output have been further demonstrated through an end-face coupling system and investigated with a laser beam at 532 nm wavelength, which have achieved two splitting ratios including 73 %: 12.5 %: 12.5 %: 2 % with a deviation less than 3 %, and 25 %: 25 %: 25 %: 25 % with a deviation less than 5 %. These performances with high consistency manifest that these devices can emerge into kinds of 3D optical applications with the ability of 3D spatial optical signal processing. Moreover, our work further proves that femtosecond laser direct writing technology presents absolute advantages in processing 3D micro-nano devices in transparent materials for on-chip integration.

Extraordinary thermal conductivity for carbon nanotube encapsulated linear carbon chain

Carbyne is a sp1 linear carbon chain (LCC) with characteristics of strong chemical reactivity and extreme instability under environmental conditions, which has become an obstacle to the application of LCC with high thermal and electrical conductivity. Utilizing CNT as a container to store LCC is one of the most feasible ways to realize LCC applications. However, current research of LCC encapsulated in CNT (LCC@CNT) focuses on its preparation and lacks of in-depth exploration of the intrinsic heat transfer mechanism. This paper reports the high axis thermal conductivity of LCC@CNT, explore the thermal transport enhancement degree of LCC@CNT under a wide temperature range and multiple diameters, and analyzed the underling mechanism through crucial thermal parameters and phonon theory. When LCC is loaded in CNT, the axial thermal conductivity of CNT is further increased by 15 %. Moreover, LCC@CNT shows the lower sensitivity diameter than pristine CNT. This work is expected to provide data support for the application of LCC, the lower production standard of CNT, and also attempt the higher efficient one-dimensional thermal energy transfer micro devices.

Facet-governed frictional behavior in graphene/h-BN heteronanotubes

Superlubricity, a state characterized by ultra-low friction and nearly-zero wear, has conventionally been linked to planar incommensurate interfaces between heterogeneous van der Waals layered materials. In this work, our investigation introduces a novel perspective by highlighting the pivotal role of curvature in heterostructures. Employing our recently developed anisotropic interlayer force field, we demonstrate the profound impact of size and chirality on the morphological characteristics, specifically circumferential faceting, of heterogeneous graphene/h-BN nanotubes. This exploration unravels a consequential transition from a superlubric to a high-friction state, coinciding with the transformation of nanotube cross-sections from cylindrical to faceted shapes. The induction of a faceted scenario triggers redistribution of moiré-dependent distortion deformation during sliding, resulting in a transition from a stick-slip mode to a high-friction state. This stands in stark contrast to the smooth-sliding mode (superlubric state) observed in non-faceted heterogeneous nanotubes. Our discoveries provide valuable insights for the intentional design of quasi one-dimensional van der Waals metamaterials and devices with tunable tribological properties, and expand the current understanding of superlubricity.

Improvement of the Sb2Se3/Si tandem cell and simulation in SCAPS

In the work, tandem solar cells were designed to achieve improved efficiency using Sb2Se3/Si as the materials. The work involved simulating the Sb2Se3/Si structures, where Sb2Se3 served as the top cell and Si as the bottom cell, under AM1.5 G solar spectrum illumination using the one-dimensional device simulator Scaps. The obtained results demonstrated a significant increase in the efficiency of the Sb2Se3/Si tandem solar cell. Initially, the top cell had an efficiency of 14.29%, while the bottom cell had an efficiency of 11.22% when considered as single cells in a row. When used in tandem, the efficiency of the Sb2S3/Si tandem cell improved to 14.6%. Additionally, there were notable improvements in the electrical parameters of the solar cell. The overall efficiency (ƞ) reached 21.41%, the open-circuit voltage (Voc) was 1.37volts, the short-circuit current density (Jsc) was 19.78 mA/cm2, and the fill factor (FF) reached 78.62%. These results highlight the success of the Sb2S3/Si tandem solar cell in achieving higher efficiency and improved electrical performance compared to single cells.

Field-based recovery technique for improved adaptive finite element analysis of photonic devices

A new adaptive finite element (FE) technique is proposed to enhance the accuracy of the solution of wave propagation in integrated photonic devices. The suggested recovery technique improves significantly the finite element convergence rate compared to refinement techniques. The method refines the elements based on the field distribution. This recovery technique estimates the error at each element by comparing the linear FE solution and the recovery solution using least-squares method. The numerical aspects and accuracy of the method are investigated using the light propagation in both one-dimensional and two-dimensional photonic devices.

Aramid nanofiber-reinforced MXene/PEDOT:PSS hybrid fibers for high-performance fiber-shaped supercapacitors

In recent years, a great deal attention has been paid to one-dimensional fiber-shaped wearable energy storage devices, but further exploration is still needed to obtain fiber-shaped devices with high mechanical and electrochemical performance to meet the requirements of stretching, twisting and squeezing deformation in daily use. Herein, high-performance aramid nanofiber-reinforced (ANF) MXene/PEDOT:PSS hybrid fibers were fabricated by a simple and tractable wet spinning strategy. In this strategy, ANF played the role of fiber reinforcement and barrier for the MXene layer, not only greatly enhancing the mechanical properties of fibers, but also effectively preventing the re-stacking of MXene layers. As a kind of spinnable conductive polymer, PEDOT:PSS can effectively improve the spinnability of fibers. The obtained hybrid fiber exhibited high tensile strength and high conductivity. Meanwhile, the assembled all solid-state fiber-shaped supercapacitor (FSC) showed a high energy density of 9.8 mWh cm−3 at the power density of 250.7 mW cm−3. Besides, the assembled FSC displayed outstanding cycle performance (86.9% capacitance retention after 10 000 cycles) and excellent flexibility. It is worth noting that the FSC could be extended in series to meet the needs of different equipment. This work provides a good reference for the manufacture of wearable high-performance fiber-shaped devices by facile wet spinning.

Experimental study on composite flocculant-electroosmosis combined with segmented solidification treatment of high-water-content slurry

To address the challenges related to high drainage efficiency, energy consumption, and turbidity in traditional electroosmosis methods, particularly for mud with ultra-high water content and high clay content, this study proposes a novel research approach: the combined flocculant-electroosmosis combined with segmented solidification treatment of high-water-content slurry.This study explores the mechanism of action and drainage effect of the composite flocculant-electroosmotic method using a self-developed one-dimensional electroosmosis test device. The test results show that there is an optimal ratio of organic flocculant (anionic polyacrylamide,APAM) and inorganic flocculant (polymeric aluminum chloride,PAC,and anhydrous calcium chloride,CaCl2) combined with the composite flocculant.Compared with the traditional single flocculant-electroosmosis method, the drainage volume of the composite flocculant-electroosmotic combined method is increased by an average of 73.76%. Although the total electroosmotic energy consumption and anode corrosion of the composite flocculant group have increased, the average electroosmotic energy consumption coefficient and anode corrosion coefficient are higher, indicating that the energy consumption coefficient is better than that of the traditional electroosmotic group. Innovatively, segmental solidification was carried out based on the anode corrosion cracks and sudden changes in water content after the completion of electro-osmosis, which yielded excellent reinforcement effects and met the requirements of external transportation and reuse.

Effects of Bio-Organic Fertilizer on Soil Infiltration, Water Distribution, and Leaching Loss under Muddy Water Irrigation Conditions

This study analyzes the soil water infiltration characteristics under muddy water irrigation and bio-organic fertilizer conditions in the current context of muddy water irrigation rarely being used in agricultural production and in combination with the problems of water resource shortages and low soil fertility in arid and semi-arid regions. An indoor one-dimensional soil column infiltration device was used for studying the effects of four muddy water sediment concentration levels (ρ0: 0; ρ1: 4%; ρ2: 8%; ρ3: 12%) and four bio-organic fertilizer levels (FO0: 0; FO1: 2250 kg·hm−2; FO2: 4500 kg·hm−2; sFO3: 6750 kg·hm−2) on soil water infiltration, evaporation characteristics, and leaching loss. The results demonstrated that a higher muddy water sediment concentration and fertilization level resulted in a smaller wetting front distance and cumulative infiltration amount within the same time, but the infiltration reduction rate (η) gradually increased. The three infiltration models (Kostiakov, Philip, and Horton) were fitted, and it was discovered that all three had good fitting results (R2 > 0.8), with the Kostiakov model displaying the best fit and the Horton model exhibiting the worst fit. The cumulative evaporation amount and evaporation time in muddy water irrigation and fertilization conditions was consistent with the Black and Rose evaporation models (R2 > 0.9), the Black model was proved to be higher than the Rose model. In comparison to ρ0, muddy water irrigation increased conductivity and total dissolved solids (TDS) in the leaching solution, but it reduced cumulative evaporation, soil moisture content, the uniformity coefficient of soil water distribution, and leaching solution volume. Compared with FO0, the application of bio-organic fertilizer increased soil water content and reduced soil water evaporation while also reducing the leaching solution volume, conductivity, and TDS in the leaching solution. The results of this research can provide scientific reference for the efficient utilization of muddy water irrigation and the rational application of bio-organic fertilizer.

Comphy v3.0—A compact-physics framework for modeling charge trapping related reliability phenomena in MOS devices

Charge trapping plays an important role for the reliability of electronic devices and manifests itself in various phenomena like bias temperature instability (BTI), random telegraph noise (RTN), hysteresis or trap-assisted tunneling (TAT). In this work we present Comphy v3.0, an open source physical framework for modeling these effects in a unified fashion using nonradiative multiphonon theory on a one-dimensional device geometry. Here we give an overview about the underlying theory, discuss newly introduced features compared to the original Comphy framework and also review recent advances in reliability physics enabled by these new features. The usefulness of Comphy v3.0 for the reliability community is highlighted by several practical examples including automatic extraction of defect distributions, modeling of TAT in high-κ capacitors and BTI/RTN modeling at cryogenic temperatures.

Truly form-factor–free industrially scalable system integration for electronic textile architectures with multifunctional fiber devices

An integrated textile electronic system is reported here, enabling a truly free form factor system via textile manufacturing integration of fiber-based electronic components. Intelligent and smart systems require freedom of form factor, unrestricted design, and unlimited scale. Initial attempts to develop conductive fibers and textile electronics failed to achieve reliable integration and performance required for industrial-scale manufacturing of technical textiles by standard weaving technologies. Here, we present a textile electronic system with functional one-dimensional devices, including fiber photodetectors (as an input device), fiber supercapacitors (as an energy storage device), fiber field-effect transistors (as an electronic driving device), and fiber quantum dot light-emitting diodes (as an output device). As a proof of concept applicable to smart homes, a textile electronic system composed of multiple functional fiber components is demonstrated, enabling luminance modulation and letter indication depending on sunlight intensity.

Domain wall nature of sketched LaAlO3/SrTiO3 nanowires

The rich electron correlations and highly coherent transport in reconfigurable devices sketched by a conductive atomic force microscope tip at the $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}$ interface have enabled the oxide platform an ideal playground for studying correlated electrons and quantum technological applications. Why these one-dimensional devices possess enhanced properties over the two-dimensional interface, however, has remained elusive. Here, we provide evidence that one-dimensional $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}$ nanowires are intrinsically ferroelastic domain walls by nature through thermodynamic study. We have observed spreading resistance anomalies under thermostimulus and temperature cycles with characteristic temperatures matching domain-wall polarity. This information is crucial in understanding the novel phenomena including superconductivity and high mobility quantum transport.

Structural design of BaSi2 solar cells with a-SiC electron-selective transport layers

Sputter-deposited polycrystalline BaSi2 films capped with a 5 nm thick a-SiC layer showed high photoresponsivity. This means that the a-SiC layer functions as a capping layer to prevent surface oxidation of BaSi2. Based on the measured absorption edge, the electron affinity of the a-SiC layer, and the work function of the TiN layer, the a-SiC is considered to act as an electron transport layer (ETL) for the BaSi2 light absorber layer/a-SiC interlayer/TiN contact structure in a BaSi2 solar cell. Using a 10 nm thick p+-BaSi2 layer as a hole transport layer, we investigated the effect of the BaSi2/a-SiC layered structure on the device performance of a BaSi2-pn homojunction solar cell by a one-dimensional device simulator (AFORS-HET v2.5). The a-SiC ETL effectively separates photogenerated carriers and allows transport of electrons while blocking holes to achieve an efficiency of 22% for a 500 nm thick BaSi2 light absorber layer.

Nonlocal transport of heat in equilibrium drift-diffusion systems

The amount of heat an integer quantum Hall edge state can carry in equilibrium is quantized in universal units of the heat flux quantum ${J}_{q}=\frac{\ensuremath{\pi}{k}_{B}^{2}}{12\ensuremath{\hbar}}{T}^{2}$ per edge state. We address the question of how heat transport in realistic one-dimensional devices can differ from the usual chiral Luttinger liquid theory. We show that a local measurement can reveal a nonquantized amount of heat carried by the edge states, despite a globally equilibrium situation. More specifically, we report a heat enhancement effect in edge states interacting with Ohmic reservoirs in the presence of nonlocal interactions or chirality-breaking diffusive currents. In contrast to a nonequilibrium, nonlinear drag effect, we report an equilibrium, linear phenomenon. The chirality of the edge states creates additional correlations between the reservoirs, reflected in a higher-than-quantum heat flux in the chiral channel. We show that for different types of coupling the enhancement can be understood as static or dynamical back action of the reservoirs on the chiral channel. We show that our results qualitatively hold by replacing the dissipative Ohmic reservoirs by an energy-conserving mesoscopic capacitor and consider the respective transmission lines for different types of interaction.

Experimental Investigation of Water-Retaining and Unsaturated Infiltration Characteristics of Loess Soils Imbued with Microplastics

Microplastics are abundant in agricultural soils and have significant impacts on rainfall infiltration and soil water-retaining capacity. To explore the effect of microplastics on agricultural soil permeability by simulating the rainfall irrigation process, a one-dimensional vertical soil column rainfall infiltration test device was used to study the unsaturated infiltration characteristics of loess soil imbued with microplastics under rainfall conditions. The following conclusions could be obtained: the microplastic content (q), the microplastic particle size (p), and the soil density (γ) have effects on rainfall infiltration; the soil water-retaining capacity would be weakened owing to the existence of microplastics; and intermittent rainfall is preferred in agricultural irrigation. Finally, the permeability coefficient (k) and average flow rate (V) of the unsaturated soil are deduced together, and the relationship between the permeability coefficient (k) and the matrix suction (ψ) of the unsaturated loess soil containing microplastics is calculated by an example, proving good consistency between the experimental results and theoretical calculations. Microplastics represent negative effects on rainfall infiltration and soil water retention, so it is recommended to dispose of them.

Light intensity dependence of the photocurrent in organic photovoltaic devices

The competition between recombination and extraction of carriers defines the charge collection efficiency and, therefore, the overall performance of organic photovoltaic devices, including solar cells and photodetectors. In this work, we describe different components of the steady-state light intensity-dependent photocurrent (IPC) and charge collection efficiency under operational conditions. Further, we demonstrate how different loss mechanisms can be identified based on their unique signatures in the IPC. In particular, we show how IPC can be used to distinguish first-order, trap-assisted recombination from other first-order photocurrent loss mechanisms, which dominate at the low-intensity characteristic of indoor light-harvesting applications. The theoretical framework is presented and verified by a one-dimensional drift-diffusion device model. Finally, the extended IPC methodology is validated on organic thin-film photovoltaic devices. We conclude that the relatively straightforward measurement of IPC over a large dynamic range can be a powerful tool for understanding solar and indoor device fundamentals. • IPC is a tool for understanding photovoltaic device fundamentals • Photocurrent loss mechanisms are identified based on their signatures in IPC • The theoretical framework is verified with a drift-diffusion device model • Experimental demonstration of IPC method on state-of-the-art organic solar cells Zeiske et al. present a combined theoretical and experimental study of intensity-dependent photocurrent (IPC), a tool for understanding solar and indoor device fundamentals, to identify different photovoltaic device performance-limiting photocurrent loss mechanisms based on their unique signatures in IPC.

Experimental and numerical simulation of solute transport in non-penetrating fractured clay

A set of one-dimensional experimental device for solute transport in non-penetrating fractured clay are developed, which can study the laws of groundwater flow and solute transport under different hydraulic heads, fractured aperture, and thickness of non-penetrating zones. The experimental results show that the solute will quickly reach the bottom of the clay along the non-penetrating fracture, and there is an obvious dominant flow phenomenon compared with the intact clay. According to the experimental data and numerical calculation results, the model parameters of the fracture and each soil layer were identified, and the verified numerical model was used to simulate the solute transport in the non-penetrating fractured clay. The numerical results show that the increase of the thickness for the non-penetrating zone has a significant improvement on the anti-seepage ability of clay, and the increase of the hydraulic head pressure and fractured aperture leads to a faster growth rate of the solute concentration, which indicates that the solute breaks down the lower impermeable clay layer under high head pressure. The research results are of great significance for the bottom anti-seepage layer similar to landfill projects.