Vertical Alignment Research Articles

Patterning and epitaxy of large-area arrays of nanoscale complex oxide epitaxial heterostructures

A combination of block copolymer (BCP) lithography and solid-phase epitaxy can be employed to form large areas, on the order of square centimeters, of a high density of epitaxial crystalline complex oxide nanostructures. We have used BCP lithography with a poly(styrene-block-methyl methacrylate) (PS-b-PMMA) copolymer to template a nanohole array either directly on an (001)-oriented SrTiO3 (STO) single crystal substrate or on a 20 nm-thick Si3N4 layer deposited on the STO substrate. BCPs with the selected compositions assembled in a cylindrical phase with 16 nm diameter PMMA cylinders and a cylinder-to-cylinder spacing of 32 nm. The substrate was modified with an energetically non-preferential polymer layer to allow for the vertical alignment of the cylinders. The PMMA cylinders were removed using a subtractive process, leaving an array of cylindrical holes. For BCPs assembled on Si3N4/STO, the pattern was transferred to the Si3N4 layer using reactive ion etching, exposing the underlying STO substrate in the nanoholes. An amorphous LaAlO3 (LAO) layer was deposited on the patterned Si3N4/STO at room temperature. The amorphous LAO epitaxially crystallized within the nanoscale-patterned holes with fully relaxed lattice parameters through solid phase epitaxy, resulting in the formation of nanoscale LAO/STO epitaxial heterostructures.

Tuning the Optoelectronic Properties of Pulsed Laser Deposited “3D”‐MoS2 Films via the Degree of Vertical Alignment of Their Constituting Layers (Advanced Optical Materials 15/2024)

Tuning the Optoelectronic Properties of Pulsed Laser Deposited “3D”‐MoS₂ Films via the Degree of Vertical Alignment of Their Constituting Layers (Advanced Optical Materials 15/2024)

Design and Analysis of a Narrow Linewidth Laser Based on a Triple Euler Gradient Resonant Ring

We designed a narrow-linewidth external-cavity hybrid laser leveraging a silicon-on-insulator triple Euler gradient resonant ring. The laser’s outer cavity incorporates a compact, high-Q resonant ring with low loss. The straight waveguide part of the resonant ring adopts a width of 1.6 μm to ensure low loss transmission. The curved section is designed as an Euler gradient curved waveguide, which is beneficial for low loss and stable single-mode transmission. The design features an effective bending radius of only 26.35 μm, which significantly improves the compactness of the resonant ring and, in turn, reduces the overall footprint of the outer cavity chip. To bolster the laser power and cater to the varying shapes of semiconductor optical amplifier (SOA) spots, we designed a multi-tip edge coupler. Theoretical analysis indicates that this edge coupler can achieve an optical coupling efficiency of 85%. It also reveals that the edge coupler provides 3 dB vertical and horizontal alignment tolerances of 0.76 μm and 2.4 μm, respectively, for a spot with a beam waist radius of 1.98 μm × 0.99 μm. The outer cavity, designed with an Euler gradient micro-ring, can achieve a side-mode suppression ratio (SMSR) of 30 dB within a tuning range of 100 nm, with a round-trip loss of the entire cavity at 1.12 dB, and an expected theoretical laser linewidth of 300 Hz.

Overlay Mark Design Using Irregular Grating Patterns

Overlay refers to controlling the vertical alignment and misalignment between circuit patterns manufactured in the previous process and circuit patterns manufactured in the current process during the stacking process of circuit patterns in the semiconductor manufacturing process. A critical factor in ensuring precise overlay measurements is using an optimized overlay mark design. Many semiconductor manufacturers have put considerable effort into optimizing overlay measurement marks to reduce high costs. However, image-based overlay measurement encounters several challenges, including resolution degradation, image distortion, and noise introduction during digital data conversion. These issues can amplify the uncertainty of overlay measurements, impair optical resolution, and heighten the risk of mismeasurement. In this paper, we introduce irregular grating patterns designed to address the principal challenges faced by the commonly utilized Advanced Imaging Metrology (AIM) marks, namely large overlays and image distortion. Furthermore, we propose an overlay mark capable of precisely identifying overlays exceeding half a pitch and incorporating as much data as possible within the limits of optical resolution. This aims to improve overlay measurement performance. The experimental findings demonstrate that the proposed Pulsated Grating Target (PGT) mark enhances overall measurement uncertainty by approximately 17% compared to the AIM mark. The practical applicability of the PGT was validated through experiments, and we achieved enhanced precision and reliability in overlay measurements by resolving the issue of large overlays—the most significant challenge with grating patterns—and simultaneously enhancing mark performance.

Design of curvilinear sections in vertical alignment of roads and railways using general transition curves

Creation of road and railway routes in general and also design of vertical alignment in particular constitute an significant engineering problem. The vertical alignment of roads, and especially of railways, is of great importance for passenger comfort under high-speed driving conditions. This requires alignment smoothness to a greater extent. In practice, the dominant tendency is to consider vertical arcs as parabolic curves (quadratic or cubic). Other solutions have been also proposed and analyzed in the literature, thus providing an alternative approach to traditional methods. This paper describes a design method of vertical arcs using the so-called general transition curves. These curves describe the entire curvilinear transition between two straight lines using a single equation, and the curvature at the contact points with the straight lines is zero, which is of great practical significance in the light of vehicle motion dynamics. As a result, relevant research shows that general transition curves, compared to other curves, provide a more favorable distribution of lateral changes of acceleration. The paper deals not only with appropriate design procedures of a general nature, but also specific procedures of fitting vertical arcs to preset points. The methods for designing vertical arcs constitute a useful extension of available methods, and offer a valuable tool for engineers and designers of road and railway routes.

Terahertz-polarizing effect based on geometric anisotropy of Ti3C2Tx MXene nanosheets

Two-dimensional (2D) nanomaterials have garnered considerable attention due to their unique properties, such as thinness and excellent electronic properties. The inherent anisotropy of 2D nanomaterials, which is characterized by their high aspect ratio, can maximize the directional functionality to enhance the conductivity and utilization of edges. Here, we demonstrate how to utilize the edges of titanium carbide (Ti3C2Tx) MXene nanosheet to control the linear polarization in the terahertz (THz) frequency range. By a simple and unique vertical alignment exploiting the high surface charge and excellent colloidal dispersibility of MXene nanosheets, MXene nanosheets are vertically oriented along an applied AC electric field. The well-aligned edges justify the THz polarizing effect, revealing outstanding performances such as the broadband coverage in 0.2–1.5 THz and an exceptional extinction ratio reaching 20 dB. Furthermore, we vary the local orientation of the vertical MXene nanosheets by tailoring the applied electric field, enabling spatially controllable polarization capabilities. Our results can provide a generic tool for the utilization of 2D nanomaterials in diverse potential applications in optics and electronics.

Expansion-flow-modulated 3D printing of vertically aligned graphene photofuel cell

Channel-aligned regulation of photoelectrode within the bulk structure to generate eminent light absorbance and high-level pollutant adsorption is pivotal but challenging for realizing high-performance photofuel cell (PFC) system. Herein, we demonstrated an effective and scalable expansion-flow-modulated direct ink writing (DIW) 3D printing strategy for controllably constructing microlattice photoelectrode, with multiscale well-interconnected oriented channels built by layer-by-layer highly-regular assembly of filaments and vertical alignment of graphene nanosheets within filaments as well as uniform coupling of abundant photoactive nanoparticles to highly ordered channel walls. The unique architectural features enabled high-speed and effective diffusion/trapping of wastewater pollutants throughout the entire photoelectrode, and meanwhile facilitated ready spreading of incident light into the photoelectrode interior to yield high light absorption. As a result, an integrated 3D-printed vertically-aligned PFC (3DP VAPFC) assembled with as-fabricated photoelectrode exhibited its powerful capability for efficiently converting wastewater pollutants into electric energy under sunlight, with remarkable cycling stability and maximum power density of 0.11 mW cm−2. This work opens a promising route for architecting advanced photoelectrode toward PFC devices with highly efficient degradation and electricity generation of pollutants.

The role of occipital condyle and atlas anomalies on occipital cervical fusion outcomes in Chiari malformation type I with syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium.

Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF). The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio. Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95). The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.

Formation of one-dimensionally self-aligned Si-QDs and their local electron discharging properties

Self-aligned Si-quantum-dots (Si-QDs) with an areal density as high as ∼1011 cm−2 have been fabricated on ultrathin SiO2 by using a ∼4.5 nm thick poly-Si on insulator (SOI) substrate, and controlling low-pressure CVD using monosilane (SiH4), and followed by thermal oxidation. By controlling the thermal oxidation processes of Si-QDs and the poly-Si layer, we have successfully demonstrated the vertical alignment of Si-QDs, where the Si-QDs are also used as a shadow mask of the underlying poly-Si layer. We also demonstrated in-plane alignment of the one-dimensionally self-aligned Si-QDs on line-patterned SiO2. In addition, from surface potential measurements by using atomic force microscopy/Kelvin probe force microscopy, we confirmed that the initial surface potential change caused by valence electron extraction from the dots to the tip was stably maintained until ∼120 min, implying the quantum confinement effect at discrete energy levels of the upper and lower-QDs.

Multi-dimensional hybridized TPMS with high energy absorption capacity

Lattice structures based on triply periodic minimal surfaces (TPMSs) have received extensive research attention due to their lightweight, tremendously high ductility, and excellent energy absorption. In this study, the advantages of several types of TPMSs-based lattice structures were integrated by proposing a multi-dimensional hybrid design for the first time. Based on the P, IWP, and FRD structures, one-dimensional (1D), 2D, and 3D hybridizations were successfully achieved by using the Sigmoid function. The technique of powder bed fusion of metal using a laser beam (PBF–LB/M) was utilized to fabricate the designed TPMS structures with Al–Si10–Mg powder. Their mechanical properties under different loading directions were investigated both experimentally and numerically. The results demonstrate that the hybridization strategy effectively modifies the mechanical behaviour of the TPMS structures. When the hybridization direction aligns parallel to the compression direction, the hybrid structure exhibits greater specific energy absorption, while vertical alignment results in a higher Young's modulus. Notably, the 2D hybrid P–FRD structure possesses the most excellent mechanical properties under parallel compression. Moreover, the 1D and 2D hybrid structures exhibit superior specific energy absorption than the uniform structure, with maximum energy absorption of 45.02% and 52.81%, respectively. The proposed hybrid design strategies are expected to accelerate the application of energy-absorbing structures in practical engineering.

High dielectric performance and thermal conductivity dielectric composite film via vertical alignment of hybrid BaTiO3 nanofibers

The arrangement of anisotropic dielectric fillers in polymer matrix can lead to a significant enhancement of dielectric properties along a specific direction, enabling the rapid development of integrated circuits and high-performance microelectronic devices. In this work, magnetic barium titanate nanofibers/polyimide composite films (mBT NFs/PI) with vertically oriented structures were constructed with the assistant of magnetic field. The dielectric constant was significantly increased from 20.8 to 39.1 at a filler content of 30 wt%, as compared to the randomly aligned films. However, the breakdown strength was affected. Addressing this issue, an optimized core-shell structure was fabricated by introducing insulated and thermo-conductive boron nitride (BN) “shell” on the surface of mBT NFs by coaxial electrospinning. The obtained mBT@BN/PI nanocomposite exhibits improved thermal conductivity and breakdown strength, while maintaining a high dielectric constant. This work highlights an effective strategy to achieve excellent dielectric properties and thermal conductivity for high-temperature dielectric capacitor materials.

A Novel Thermal Interface Material Composed of Vertically Aligned Boron Nitride and Graphite Films for Ultrahigh Through-Plane Thermal Conductivity.

The relentless drive toward miniaturization in microelectronic devices has sparked an urgent need for materials that offer both high thermal conductivity (TC) and excellent electrical insulation. Thermal interface materials (TIMs) possessing these dual attributes are highly sought after for modern electronics, but achieving such a combination has proven to be a formidable challenge. In this study, a cutting-edge solution is presented by developing boron nitride (BN) and graphite films layered silicone rubber composites with exceptional TC and electrical insulation properties. Through a carefully devised stacking-cutting method, the high orientation degree of both BN and graphite films is successfully preserved, resulting in an unprecedented through-plane TC of 23.7Wm-1K-1 and a remarkably low compressive modulus of 4.85MPa. Furthermore, the exceptional properties of composites, including low thermal resistance and high resilience rate, make them a reliable and durable option for various applications. Practical tests demonstrate their outstanding heat dissipation performance, significantly reducing CPU temperatures in a computer cooling system. This research work unveils the possible upper limit of TC in BN-based TIMs and paves the way for their large-scale practical implementation, particularly in the thermal management of next-generation electronic devices.

Tuning the Optoelectronic Properties of Pulsed Laser Deposited “3D”‐MoS2 Films via the Degree of Vertical Alignment of Their Constituting Layers

AbstractPulsed‐laser‐deposition (PLD) is used to deposit MoS2 thin films at substrate temperatures (Td) ranging from 25 to 700 °C. A Td = 500 °C is identified as the optimal temperature that yields MoS2 films consisting of highly‐crystallized 2H‐MoS2 phase with a strong (002) preferential orientation, a direct optical bandgap (Eg) of ∼1.4 eV and a strong photoresponse of ∼1500%. Raman spectroscopy revealed that the degree of vertical alignment of MoS2 layers in the films also reaches its maximum at Td = 500 °C. High‐resolution‐transmission‐electron‐microscopy has provided a clear‐cut evidence that the PLD‐MoS2 films predominantly consist of vertically aligned MoS2 layers over all the film thickness of ∼90 nm, enabling those “3D” films to behave as a direct‐bandgap “2D‐MoS2” with exceptional optoelectronic properties. Indeed, at Td = 500 °C, the PLD‐MoS2 based photodetectors (PDs) devices are shown to exhibit the highest responsivity (R) and detectivity (D*) values (125 mA W−1 and 9.2 × 109 Jones, respectively) ever reported for large area (≥ 1 cm2) MoS2‐based PDs operating at a voltage as low as 1 V. For the first time, a constant‐plus‐linear relationship between Eg, R, and D* of the PDs and the degree of vertical alignment of the MoS2 layers is established. Such a correlation is fundamental for the controlled growth of PLD‐MoS2 films and the tuning of their properties in view of their integration with standard large‐scale‐integration processing.

Highly thermally conductive and insulating composites fabricated through the hot-pressing of hollow structured h-BN/rGO hybrid filler

Polymer composites have several advantages: affordability, ease of processing, and versatile applications. In this study, hexagonal boron nitride (h-BN)/epoxy spheres were fabricated using NaCl, then washing away the NaCl with water to create h-BN/epoxy hollow structures. Reduced graphene oxide (r-GO) was subsequently wrapped around these structures to produce h-BN/r-GO/epoxy hollow structures. These structures were then fabricated into composites through a hot pressing method involving high pressure and heat, which achieved a vertical alignment of the h-BN components to establish a heat transfer path, with r-GO evenly dispersed throughout. The thermal conductivity of the h-BN/r-GO/epoxy composite was measured as 4.12 W/m·K, representing a 2060 % increase compared to that of neat epoxy. Despite incorporating electrically conductive r-GO, the h-BN/r-GO/epoxy composite maintained its insulating properties. This is attributed to the even distribution of insulating h-BN within the h-BN/r-GO/epoxy hollow structures.

Vertically-Aligned Card-House Structure for Composite Solid Polymer Electrolyte with Fast and Stable Ion Transport Channels.

All-solid-state lithium batteries (ASSLBs) are highly promising as next-generation energy storage devices owing to their potential for great safety and high energy density. This work demonstrates that composite solid polymer electrolyte with vertically-aligned card-house structure can simultaneously improve the high rate and long-term cycling performance of ASSLBs. The vertical alignment of laponite nanosheets creates fast and uniform Li+ ion transport channels at the nanosheets/polymer interphase, resulting in high ionic conductivity of 8.9 × 10-4 S cm-1 and Li+ transference number of 0.32 at 60°C, as well as uniformly distributed solid electrolyte interphase. Such electrolyte is characterized by high mechanical strength, low flammability, excellent structural stability and stable ion transport channels. In addition, the ASSLB cell with the electrolyte and LiFePO4 cathode delivers a high discharge specific capacity of 124.8 mAh g-1, which accounts for 85.6% of its initial capacity after 500 cycles at 1C. The reasonable design through structural control strategy by interconnecting the vertically-aligned nanosheets open a way to fabricate high performance composite solid polymer electrolytes.

Manipulation of Crystal Orientation and Phase Distribution of Quasi-2D Perovskite through Synergistic Effect of Additive Doping and Spacer Engineering.

The diammonium precursor 1,4-phenylenedimethanammonium (PDMA) was used as a large organic spacer for the preparation of Dion-Jacobson-type quasi-2D perovskites (PDMA)(MA)n-1PbnI3n+1 (MA = methylammonium). Films with composition ⟨n⟩ = 5 comprised randomly orientated grains and multiple microstructural domains with locally differing n values. However, by mixing the Dion-Jacobson-type spacer PDMA and the Ruddlesden-Popper-type spacer propylammonium (PA), the crystal orientation in both the vertical and the horizonal directions became regulated. High crystallinity owing to well-matched interlayer distances was observed. Combining this spacer-engineering approach with the addition of methylammonium chloride (MACl) led to full vertical alignment of the crystal orientation. Moreover, the microstructural domains at the substrate interface changed from low-n (n = 1, 2, 3) to high-n (n = 4, 5), which may be beneficial for hole extraction at the interface between perovskite and hole transport layer due to a more finely tuned band alignment. Our work sheds light on manipulating the crystallization behavior of quasi-2D perovskite and further paves the way for highly stable and efficient perovskite devices.

Redesain Jalan Akses Dermaga IHM Dengan Implementasi Building Information Modelling

The rapid development of Indonesian construction, especially in the capital city of the Nusantara, which is undergoing intense development, requires all parties involved to work effectively and efficiently. A method is needed to face these challenges. The BIM method is considered superior in terms of effectiveness and efficiency compared to conventional methods. In the PT ITCI Hutani Manunggal dock access road construction package, the planning is still using conventional methods. So that the package is re-planned by implementing BIM. This research aims to redesign the horizontal and vertical alignment planning of roads located in Penajam Paser Utara Regency with the implementation of Building Information Modeling. In the research process, the data analysis technique uses the BIM method which consists of 4 stages, namely modeling of plan traces and profiles, horizontal alignment redesign, vertical alignment redesign, and 3D BIM visualization. This research uses secondary data, namely detailed engineering design drawings and lidar contours. The redesign results obtained 27 Intersect Points and 72 Vertical Intersect Points made road geometric adjustments in order to meet the minimum permitted standards. The implementation of BIM provides a clear initial picture of the form of road infrastructure that is built in an integrated manner.

Efficient Ion Percolating Network for High-Performance All-Solid-State Cathodes.

All-solid-state lithium batteries (ASSLBs) face critical challenges of low cathode loading and poor rate performances, which handicaps their energy/power densities. The widely-accepted aim of high ionic conductivity and low interfacial resistance seems insufficient to overcome these challenges. Here, it is revealed that an efficient ion percolating network in the cathode exerts a more critical influence on the electrochemical performance of ASSLBs. By constructing vertical alignment of Li0.35La0.55TiO3 nanowires (LLTO NWs) in solid-state cathode through magnetic manipulation, the ionic conductivity of the cathode increases twice compared with the cathode consisted of randomly distributed LLTO NWs. The all-solid-state LiFePO4/Li cells using poly(ethylene oxide) as the electrolyte is able to deliver high capacities of 151mAhg-1 (2C) and 100mAhg-1 (5C) at 60°C, and a room-temperature capacity of 108mAhg-1 can be achieved at a charging rate of 2C. Furthermore, the cell can reach a high areal capacity of 3mAhcm-2 even with a practical LFP loading of 20mgcm-2. The universality of this strategy is also presented showing the demonstration in LiNi0.8Co0.1Mn0.1O2 cathodes. This work offers new pathways for designing ASSLBs with improved energy/power densities.

Dancers Show More Accurate Trunk-Pelvic Joint Angle Reproduction While Wearing a Jacket Augmented With Elastic Bands.

Purpose: The Backalast® compression jacket is intended to improve posture and proprioception of the trunk and shoulder girdle for dancers and dance students during dance training by way of elastic bands in the rear of the garment (which include bands enclosing the inferior thorax). This study was intended to investigate whether there is evidence to support those objectives. Materials and Methods: Fifteen dance students participated (4 male, mean age 19.9 ± 1.4 years old). The dependent variables of trunk-pelvis angle and proximity of trunk axis to global vertical for each participant were measured using optical motion capture before and after the completion of a series of trunk movements. The Helen Hayes model, which we used to represent the trunk, includes the shoulder girdles as part of the trunk. We compared the effect of the type of garment (Backalast® or control compression shirt) worn upon the 2 dependent variables, within-subject with paired t-tests. The order of whether Backalast® or control compression shirt was worn first was alternated between participants. Results: The pre/posttest difference in trunk proprioception as represented by the construct of ability to reproduce trunk-pelvis angle wearing the Backalast® was 0.8° ± 0.8°, but for the control shirt, the difference was 1.8° ± 1.4°, P = .03. The difference between garments in vertical trunk alignment, measured after the series of trunk movements, was not significant. Conclusion: Our findings suggest that the Backalast® can help enhance trunk proprioception when compared to the control compression shirt, although it did not change the angle at which the participants' held their trunks while standing erect (proximity to global vertical).

Articulación de las políticas nacionales del Perú con la transformación digital por medio de la Política de Estado 35: una tarea pendiente

The objective of this research was to evaluate the articulated planning for the digital transformation, specifically of the Peruvian State Policy 35 [PE35], in the national policies (sectoral and multisectoral) of Peru. For this, the methodology was qualitative in approach, interpretive in design, and descriptive in level. The data came from the vertical alignment subchapters or annexes of the policies studied. The method was documentary analysis, instrumentalized by an analysis sheet. It was determined that only the Ministry of Agriculture and the Ministry of Defense were fully aligned with the digital transformation; that the Presidency of the Council of Ministers and the Ministry of Economy and Finance, only half; and that the Ministry of Production, the Ministry of Labor and Employment Promotion, the Ministry of Health, and others, did not even have a policy aligned with the PE35. It was concluded that there is a gap in the articulation of Peruvian national policies with the digital transformation, through the PE35.