With the continuous drive for miniaturizing optoelectronic devices, 2D layered halide perovskites have been intensively studied in photo-electric conversion for their superior stability and remarkable performance even at their atomically thin structure. Although UV sensing is reported, its deployment in visible light detection is yet to be realized. We use a rational halogen mixing strategy to first report an experimental visible light photodetector of Cs2PbBr2I2 with a bandgap of 1.96 eV. Through a rigorous experimental investigation in conjunction with computational modeling, we achieve a high-quality active layer with large grains and small trap density yielding extraordinary performance. We observe a high quantum efficiency in our vertical photodetector (VPD) owing to trap-mediated persistent photoconductivity (PPC). Our optoelectronic analysis reveals that bulk trap states are responsible for the observed EQE gain, which retard electrons transit time by trap/de-trap process while multiple holes are extracted to the external circuit. The device exhibits an external quantum efficiency exceeding 200%, a responsivity of 830 mA W-1 at 488 nm, and an on/off ratio approaching 105. This gain strategy exploiting the trap-assisted carrier delay coupled with the light-induced electric field could be a potential approach for next-generation, energy-efficient, self-powered photodetectors.

With the continuous drive for miniaturizing optoelectronic devices, 2D layered halide perovskites have been intensively studied in photo‐electric conversion for their superior stability and remarkable performance even at their atomically thin structure. Although UV sensing is reported, its deployment in visible light detection is yet to be realized. We use a rational halogen mixing strategy to first report an experimental visible light photodetector of Cs 2 PbBr 2 I 2 with a bandgap of 1.96 eV. Through a rigorous experimental investigation in conjunction with computational modeling, we achieve a high‐quality active layer with large grains and small trap density yielding extraordinary performance. We observe a high quantum efficiency in our vertical photodetector (VPD) owing to trap‐mediated persistent photoconductivity (PPC). Our optoelectronic analysis reveals that bulk trap states are responsible for the observed EQE gain, which retard electrons transit time by trap/de‐trap process while multiple holes are extracted to the external circuit. The device exhibits an external quantum efficiency exceeding 200%, a responsivity of 830 mA W −1 at 488 nm, and an on/off ratio approaching 10 5 . This gain strategy exploiting the trap‐assisted carrier delay coupled with the light‐induced electric field could be a potential approach for next‐generation, energy‐efficient, self‐powered photodetectors.

Silicon dioxide (SiO2) microstructures are widely employed in photonic and microelectronic devices. However, achieving well-controlled device profiles typically relies on costly dry-etching tools and complex fabrication workflows. Wet etching of SiO2 in hydrofluoric acid (HF), while attractive for its simplicity and scalability, is commonly regarded as inherently isotropic, limiting sidewall control. This work demonstrates that pronounced and continuously tunable anisotropy can be achieved using a buffered oxide etch (BOE)-based wet etching strategy. By systematically modulating etchant chemistry, surfactant-assisted interfacial transport, and etching temperature, anisotropic selectivity is engineered at a relatively high etch rate while maintaining smooth and uniform profiles, without relying on high-cost fabrication methods. In particular, reducing the etching temperature leads to a reduction in the sidewall angle of 33% and an increase in the vertical-to-lateral etch-rate ratio of 16%. These results establish BOE-based wet etching as a simple, scalable, and cost-effective approach for near-anisotropic SiO2 microfabrication with improved profile fidelity.

Carbon-based fibrous supercapacitors (FSSCs) are promising power sources for wearable electronics, often compounding with transition metal oxides (TMOs) to improve energy density. However, conventional methods introducing TMOs onto exterior surfaces of carbon-based fibers typically degrade electrical transport and cycle stability. Herein, nanoconfined MnO@Mn2O3 heterojunctions within carbon nanotube (CNT) (MOIC) composite FSSCs stabilized by Mn & horbar;O & horbar;C bonds, exhibiting record cycle stability with 95.7% capacitance retention after 10 000 cycles and 89.4% after 50 000 cycles are reported. X-ray absorption near edge structure (XANES), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) analyses confirm MnO@Mn2O3 heterostructure, which arises through a partial phase transformation from MnO to Mn2O3, as further supported by density functional theory calculations. Mn & horbar;O & horbar;C chemical bonds, as verified through XPS, extended X-ray absorption fine structure, and XANES analyses, facilitate 3D electron transport, enabling MOIC composite fiber superior electrical conductivity than CNT fiber. The nanoconfinement of Mn2+ within CNTs, driven by capillary effects and electrostatic repulsion between protonated CNTs and Mn2+, preserves the clean exterior surfaces of CNTs. This configuration enables the successful wet-spinning of MOIC composite fibers with three times the tensile strength of fibers without nanoconfinement. This work opens new pathways for designing carbon/metal oxide hybridized supercapacitors for wearable energy storage applications.

Diamond tips are often used in Atomic Force Microscopy (AFM) to provide wear resistance and mechanical stability. However, fabricating diamond tips is a complicated and time-consuming process. Commercially available diamond tips are typically fabricated using focused ion beam (FIB) etching to create sharp tips that are then attached to a silicon cantilever, which is a high-cost process. Reactive ion etching (RIE) of diamond can produce large batches of tips in a relatively short time. However, the tip apex often remains too large for highquality imaging, primarily because the mask used for diamond etching can detach, resulting in blunt tips. In this study, we address these challenges by employing RIE with a shrinking mask to fabricate sharp diamond tips, followed by silicon etching to create high aspect ratio tip bases. Polycrystalline diamond is etched using O2/CHF3 plasma, with the process optimized to achieve the desired tip sharpness prior to silicon etching. We also optimize the mask parameters and silicon etching recipe to ensure high aspect ratio tips with a sharp diamond apex. The resultant diamond tips, supported by a silicon base, exhibit an apex of 29.5 nm and an aspect ratio of 9.63, demonstrating the effectiveness of our approach.

Atomic force microscope (AFM) systems rely on silicon (Si) probes for precise nanoscale characterization across diverse environments. However, fabricating high-aspect-ratio (HAR) and sharp Si tips and optimizing the handle geometries remain significant challenges. Conventional HAR probe fabrication methods lack scalability, precision, and cost efficiency, while cuboid-shaped handles risk obstructing laser detection and limiting compatibility. This study presents an innovative batch-fabrication strategy for high-performance Si AFM probes that integrate ultra-sharp HAR tips, rectangular cantilevers, and universally compatible stair-shaped handles. Notably, the tip fabrication process employs only low-cost microscale ultraviolet (UV) lithography, while still achieving nanoscale structural resolution. The fabricated probes exhibit a tip apex radius of 5 nm and a half-cone angle of 7.5°, enabling high-resolution and high-fidelity imaging. The novel stair-shaped handle geometry is introduced and fabricated via a single-step dry etching process, which provides unobstructed laser detection and ensures compatibility with a broad range of commercial AFM platforms. Durability testing demonstrates stable scanning performance for up to 8 hours within the 100 nm precision range, confirming the mechanical reliability of the design. This scalable, reproducible, and high-yield fabrication strategy represents a significant advancement in HAR AFM probe development, providing enhanced performance and extended applicability for diverse nanoscale imaging applications.

Aqueous sodium-ion batteries (ASIBs) offer a cost-effective and safe platform for grid-scale energy storage, but their practical application is impeded by poor energy density and limited operating time, primarily due to the sluggish Na+ intercalation kinetics and severe parasitic side reactions. Here, through multiple characterizations and molecular dynamics simulations, an unexpected phase transition of the NaMnO2 cathode and incomplete formation of phosphorus oxide interphase on the anode is observed, which causes the failure of ASIBs. To circumvent these issues, an electrolyte with phosphate bonded perchloric (PBP) superstructure is proposed to simultaneously boost cathodic Na+ transport and promote the formation of a robust Na4P2O6/Na4P2O7 interphase on the anode surface. This electrolyte design enables batteries to deliver a cathodic specific capacity of 198.21 mAh g-1 at 50 mA g-1, with prolonged operating time exceeding 1440 h and an energy density of 82.31 Wh kg-1 (based on the mass of electrode materials). Even under practical application conditions (-20 °C and a mass loading of 10 mg cm-2), the batteries remain functional and exhibit exceptional electrochemical performance. The study underscores the potential of PBP superstructure as an alternative electrolyte engineering pathway toward energy-dense and long lifespan ASIBs.

Slanted gratings, commonly used for manipulating light in various applications, are typically fabricated using conventional top-down methods. However, these methods have limitations on material choice. This paper explores the use of glancing angle deposition (GLAD) to fabricate slanted gratings with various materials and slant angles on silicon (Si) and quartz (SiO2) substrates. The process involves the first step of creating a template using electron beam lithography, lift-off, and dry etching, and the second step of electron beam evaporation at a glancing angle on the prefabricated template. The template consists of grating structures with very shallow trenches. Different materials, such as chromium (Cr), copper (Cu), aluminum oxide (Al2O3), and titanium oxide (TiO2), were used in the GLAD process to create slanted grating structures on Si or SiO2 substrates, showcasing their versatility. Here, the formation of the slanted grating is due to the shadowing effect that leads to deposition onto the protruded grating lines but not into the trench. Using TiO2 as the source material, the GLAD technique can produce slanted gratings with various angles by adjusting the deposition angle. The optical characteristics of the slanted grating prepared using GLAD were verified through simulations with COMSOL software, confirming its excellent light guide performance.

Inorganic (cesium) metal halide perovskites have been of extensive interest to the broader scientific community owing to their higher stability and breakthrough performance in photoelectric conversion. While substantial progress has been made in perovskite-based devices, they are increasingly attracting interest as potential candidates for fluorescent-based sensors in biological marker detection and quantification. Herein, a self-driven perovskite photodetector for fluorescence detection is reported, elucidating controlled charge carrier dynamics under the light matter interaction. The light-induced doping phenomenon, resulting from the migration of optically activated ions, generates an electric field that enables device operation without external power. However, the uncontrolled migration of those ions increases the dark current and reduces the stability of the output current. To address this, we fabricate a vertically stacked FTO/PEDOT: PSS/CsPbBr2I/PCBM/Ag photodetector with nonsymmetrical electrode design to trigger controlled ion migration upon light illumination, thereby improving the device performance and output stability. The photodetector, driven by induced electric field due to the directional polarization, achieves an exceptionally low dark current (similar to 298 pA), a high on/off ratio on the order of 10,5 a responsivity of 202 mA/W, a high detectivity of 2.5 x 1011 Jones, and a fast rise and decay time (190 and 100 mu s), all are measured at 0 V, surpassing the performance of many similar state-of-the-art works. These insights are crucial for practical applications where weak light detection is required, and we demonstrate the integration of this detector with a microfluidic chip for fluorescence detection from quantum dot conjugated beads. The photodetector showcased sufficient sensitivity to detect signals from quantum dot solutions as low as similar to 23 nM in a microfluidic channel, highlighting the potential for future self-powered integrated platforms for biomarker sensing applications.

This paper presents the fabrication of widely-spaced high aspect ratio ring-shape pillars (i.e. hollow pillars). Lateral etching of the pillars during deep reactive ion etching is challenging. To reduce this problem, we proposed adding sacrificial structures surrounding the pillars such that the lateral etching mainly occurs on the sacrificial structures. We designed two different kinds of sacrificial structures, one is circular ring structures surrounding the pillars, the other one is two half circle structures with two small gaps. Both sacrificial structures could help to fabricate pillars with vertical sidewalls. When the width of the sacrificial structures was well designed for a given etching condition, the sacrificial structures could be removed by ultrasonic agitation after the process with clean surface because they had been weakened by the lateral etching. Using this method, 2D widely-spaced ring-shape pillar array with 470 μm high pillars (diameter 200 μm, aspect ratio 2.35) and 370 μm deep holes (diameter 80 μm, aspect ratio 4.63) was fabricated simultaneously.

Nanocone arrays are widely employed for applications such as antireflection structures and field emission devices. Silicon nanocones are typically obtained by an etching process, but the profile is hard to attain because anisotropic dry etching generally gives vertical or only slightly tapered sidewall profiles, and isotropic dry plasma etching gives curved sidewalls. In this work, we report the fabrication of cone structures by using masked etching followed by maskless etching techniques. The silicon structure is first etched using fluorine-based plasma under the protection of a hard metal mask, with a tapered or vertical sidewall profile. The mask is then removed, and maskless etching with an optimized nonswitching pseudo-Bosch recipe is applied to achieve the cone structure with a sharp apex. The gas flow ratio of C4F8 and SF6 is significantly increased from 38:22 (which creates a vertical profile) to 56:4, creating a taper angle of approximately 80 degrees. After subsequent maskless etching, the sidewall taper angle is decreased to 74 degrees, and the structure is sharpened to give a pointed apex. The effect of an oxygen cleaning step is also studied. With the introduction of periodic oxygen plasma cleaning steps, both the etch rate and surface smoothness are greatly improved. Lastly, it was found that the aspect ratio-dependent etching effect becomes prominent for dense patterns of cone arrays, with a greatly reduced etch depth at a 600 nm pitch array compared to a 1200 nm pitch array.

Fabrication of high aspect ratio silicon nanopillars is challenging for various applications. A cryogenic silicon etching process using SF6 and O2 plasma is investigated to create silicon nanopillars with 10 μm height and tens of nanometers apex. In the process, fluorine radicals react with silicon atoms, releasing volatile SiFx byproducts and then oxygen atoms interact with SiFx and deposit a SiOxFy film acting as an inhibitor. By adjusting the O2 concentration and the forward radio frequency power, this process modifies the formation of the SiOxFy passivation film and adjusts the bombardment of ions onto the inhibitor, resulting in the desired positive taper angles of silicon pillars. Two etching steps, with higher and lower O2 concentrations, are consecutively combined to create a sharp apex and a wide base. The results demonstrate the high etching rate and controllability of cryogenic etching to obtain high aspect ratio silicon pillars with desired profiles.

In view of the wide range of applications for ultra-sharp silicon (Si) nanocones, extensive research has been conducted on their fabrication processes. However, these conventional methods pose challenges in terms of achieving uniformity, controllability, and cost-efficiency. This study presents a novel approach to fabricating Si nanocone structures through reactive ion etching (RIE) using a tapered silicon dioxide mask, followed by thermal oxidation sharpening to reduce the apex diameter to 4 nm. Here the tapered SiO2 mask with a smooth sidewall was created through a combination of RIE and a buffered oxide etchant (BOE) etching. The lithography of the oxide mask is achieved using a cost-effective (compared to electron beam lithography) maskless aligner system (MLA). Subsequently, a non-switching pseudo-Bosch process, employing sulfur hexafluoride (SF6) gas and octafluorocyclobutane (C4F8) gas, is utilized for the etching the Si nanocone structures, resulting in an average apex diameter of 30 nm. Finally, thermal oxidation followed by oxide removal further sharpens these cones to 4 nm.

Silicon (Si) nanocones have a wide range of applications in microelectromechanical systems and nanoelectromechanical systems. There is an increasing demand for precise control over the size and shape of nanocones. This paper proposed a novel method combining Si dry etch with periodic oxygen plasma shrinking, wet etch, and oxidation sharpening to achieve well-defined sharp Si nanocones. First, the standard Bosch process was employed to create the base part of nanocones. Second, two alternating steps of etching with sulfur hexafluoride/octafluorocyclobutane plasma and photoresist shrinkage with oxygen plasma were used to form the cone-shaped structures on top of the cylindrical bases. Third, to obtain a sharp tip, wet etching was carried out in either potassium hydroxide or a nitric acid/hydrofluoric (HF) acid mixture. To further sharpen the Si tips, thermal oxidation and HF dipping were conducted and the apex of nanocones can be down to 20 nm. This technique provides a cost-effective way to manufacture nanocones for various applications.

E-beam lithography is a powerful tool for generating nanostructures and fabricating nanodevices with fine features approaching a few nanometers in size. However, alternative approaches to conventional spin coating and development processes are required to optimize the lithography procedure on irregular surfaces. In this review, we summarize the state of the art in nanofabrication on irregular substrates using e-beam lithography. To overcome these challenges, unconventional methods have been developed. For instance, polymeric and nonpolymeric materials can be sprayed or evaporated to form uniform layers of electron-sensitive materials on irregular substrates. Moreover, chemical bonds can be applied to help form polymer brushes or self-assembled monolayers on these surfaces. In addition, thermal oxides can serve as resists, as the etching rate in solution changes after e-beam exposure. Furthermore, e-beam lithography tools can be combined with cryostages, evaporation systems, and metal deposition chambers for sample development and lift-off while maintaining low temperatures. Metallic nanopyramids can be fabricated on an AFM tip by utilizing ice as a positive resistor. Additionally, Ti/Au caps can be patterned around a carbon nanotube. Moreover, 3D nanostructures can be formed on irregular surfaces by exposing layers of anisole on organic ice surfaces with a focused e-beam. These advances in e-beam lithography on irregular substrates, including uniform film coating, instrumentation improvement, and new pattern transferring method development, substantially extend its capabilities in the fabrication and application of nanoscale structures.

A novel manufacturing method using the side mask and tilted reactive ion beam etching (RIBE) is proposed for the fabrication of blazed gratings. Electron beam lithography was carried out to pattern a groove with a nanoscale line width, and then appropriate mask materials were filled into the SiO2 trench by atomic layer deposition. After being etched by RIBE at specific tilted angles, the required blazed gratings were achieved. In contrast to the typical fabrication process with a patterned mask on top of the surface to be etched, V-shaped nano structures filled into the trenches were used as the side mask. During etching, the surface material located in the shadow of the side mask along incident ion beams was not etched. The depth and blazed angle of blazed gratings are determined by the height of the side mask and the mounting angle of the sample, respectively. In addition, the fabricated blazed gratings can be used as imprinting moulds to duplicate blazed gratings for augmented reality applications. Due to more options for side mask materials, this method is able to provide high repeatability and accurate controllability for fabricating blazed gratings.

High aspect ratio (HAR) structures have many promising applications such as biomedical detection, optical spectroscopy, and material characterization. Bottom-up self-assembly is a low-cost method to fabricate HAR structures, but it remains challenging to control the structure dimension, shape, density, and location. In this paper, an optimized top-down method using a combination of pseudo-Bosch etching and wet isotropic thinning/sharpening is presented to fabricate HAR silicon (Si) nanopillar and nanocone arrays. To achieve these structure profiles, electron beam lithography and reactive ion etching were carried out to fabricate silicon pillars having a nearly vertical sidewall, followed by thinning or sharpening by wet etching with a mixture of hydrofluoric (HF) acid and nitric acid (HNO3). For the dry etching step using the pseudo-Bosch process, the sidewall angle is largely dependent on the SF6/C4F8 gas flow ratio, and it was found that a vertical profile can be attained with a ratio of 22/38. For the wet etching process, a very large HNO3/HF volume ratio is shown to give smooth etching with a slow and controllable etching rate. The final structure profile also depends on the pattern density/array periodicity. When the array period is large, silicon nanopillar is thinned down, and its aspect ratio can reach 1:135 with a sub-100 nm apex. When the pillar array becomes very dense (periodicity much smaller than height), a very sharp nanocone structure is obtained after wet etching with an apex diameter under 20 nm.

Traditional nanolithography methods, such as electron beam or ion beam lithography, can be expensive and slow, limiting their applications. Edge lithography offers a promising alternative for efficiently and effectively creating nanoscale patterns using lower-cost lithography equipment with higher throughput. Our paper presents a new edge lithography technique to pattern fine structures with coarse patterns utilizing aluminum plasma dry etching without thin film deposition. The aluminum oxide layer generated on the sidewall of the Al structure during the etching process defines the final nanostructures. Our experiments show that this layer is formed through the oxidation of the aluminum layer itself, providing a simple and practical approach to creating complex nanostructures without additional steps or materials. In addition, using the non-switching pseudo-Bosch etching process, we transferred the nano-edge pattern formed in aluminum oxide into the silicon substrate. Our technique allows for cost-effective and efficient nanoscale patterning for various applications.

In dry plasma silicon etching, it is desired to have a high etching rate, a high etching selectivity to mask material, a vertical or controllable sidewall profile, and a smooth sidewall. Since the standard Bosch process (switching between SF6 and C4F8 gases) leads to a wavy/rough sidewall profile, the nonswitching pseudo-Bosch process is developed to give a smooth sidewall needed for nanostructure fabrication. In the process, SF6 and C4F8 gases are introduced to the chamber simultaneously. Here, the authors show that by introducing a periodic oxygen (O2) plasma cleaning step, that is, switching between SF6/C4F8 etching and O2 cleaning, the silicon etching rate can be significantly improved (by up to ∼55%, from 139 to 216 nm/min) without any adverse effect. This is mainly because O2 plasma can remove the fluorocarbon polymer passivation layer at the surface. The etching and cleaning step durations were varied from 5 s to 40 min and from 0 to 60 s, respectively. The fastest etching rates were obtained when the cleaning step takes roughly 10% of the total etching time.