Device Thickness Research Articles

Sub-5 nm Silicon Nanopore Sensors: Scalable Fabrication via Self-Limiting Metal-Assisted Chemical Etching.

Solid-state nanopores offer unique possibilities for biomolecule sensing; however, scalable production of sub-5 nm pores with precise diameter control remains a manufacturing challenge. In this work, we developed a scalable method to fabricate sub-5 nm nanopores in silicon (Si) nanomembranes through metal-assisted chemical etching (MACE) using gold nanoparticles. Notably, we present a previously unreported self-limiting effect that enables sub-5 nm nanopore formation from both 10 and 40 nm nanoparticles in the 12 nm thick monocrystalline device layer of a silicon-on-insulator substrate. This effect reveals distinctive etching dynamics in ultrathin Si nanomembranes, enabling precise control over nanopore dimensions. The resulting nanopore sensor, suspended over self-aligned spheroidal oxide undercuts with diameters of just a few hundred nanometers, exhibited low electrical noise and high stability due to encapsulation within dielectric layers. In DNA translocation experiments, our nanopore platform could distinguish folded and unfolded DNA conformations and maintained stable baseline conductance for up to 6 h, demonstrating both sensitivity and robustness. Our scalable nanopore fabrication method is compatible with wafer-level and batch processing and holds promise for advancing biomolecular sensing and analysis.

Highly sensitive and efficient 1550 nm photodetector for room temperature operation

Photonic quantum technologies such as effective quantum communication require room temperature (RT) operating single- or few-photon sensors with high external quantum efficiency (EQE) at 1550 nm wavelength. The leading class of devices in this segment is avalanche photodetectors operating particularly in the Geiger mode. However, for superior performance, a trade-off has to be made between temperature of operation, device thickness, and EQE. Two-dimensional (2D) materials can be used to reduce the absorber thickness and thus dark current, leading to an increase in the operating temperature, but they suffer from low EQE. We use specifically stacked bilayer hexagonal BAs, with material properties calculated from first principles, on a co-optimized dielectric photonic crystal substrate to simultaneously decrease the dark current by three orders of magnitude at RT and maintain an EQE of >99%. The device can potentially be used in avalanche mode and hence can form a basis for single photon detection.

Solution-processed spin organic light-emitting diodes based on antisolvent-treated 2D chiral perovskites with strong spin-dependent carrier transport.

Chiral perovskites, which are applied to spin organic light-emitting diodes as a spin-induced spin selectivity (CISS) layer, have attracted increasing amounts of attention. A device based on a thicker perovskite CISS layer leads to strongly spin-polarized EL emission. However, chiral perovskite films suffer from poor device performance due to difficulties in carrier injection and film quality. The effects of antisolvent dripping on the chiroptical properties of chiral perovskite films were investigated. The rapid crystallization of chlorobenzene (CB)-treated films generated a high-quality film with fewer halide vacancies and a much greater strength of asymmetric hydrogen bonding. Accordingly, the inorganic structural distortion is greater, resulting in greater chiroptical activity. The chiral perovskite thickness affects the circularly polarized electroluminescence (CP-EL) of spin-OLEDs. The statistics relating device performance and thickness are presented. The spin current polarization degree of chiral perovskites reaches approximately 86%. The maximum CP-EL asymmetry factor (g CP-EL) is 2.6 × 10-2 and maximum external quantum efficiency (EQE) of the spin-OLED device is 3.68%. Spin OLED devices based on chiral perovskites can be manipulated and controlled by thickness and antisolvent treatment. gCPEL intensities for devices based on CB-treated chiral perovskite films can be increased by about 1.75 times compared with devices based on untreated films.

Customized surface adhesive and wettability properties of conformal electronic devices.

Conformal and body-adaptive electronics have revolutionized the way we interact with technology, ushering in a new era of wearable devices that can seamlessly integrate with our daily lives. However, the inherent mismatch between artificially synthesized materials and biological tissues (caused by irregular skin fold, skin hair, sweat, and skin grease) needs to be addressed, which can be realized using body-adaptive electronics by rational design of their surface adhesive and wettability properties. Over the past few decades, various approaches have been developed to enhance the conformability and adaptability of bioelectronics by (i) increasing flexibility and reducing device thickness, (ii) improving the adhesion and wettability between bioelectronics and biological interfaces, and (iii) refining the integration process with biological systems. Successful development of a conformal and body-adaptive electronic device requires comprehensive consideration of all three aspects. This review starts with the design strategies of conformal electronics with different surface adhesive and wettability properties. A series of conformal and body-adaptive electronics used in the human body under both dry and wet conditions are systematically discussed. Finally, the current challenges and critical perspectives are summarized, focusing on promising directions such as telemedicine, mobile health, point-of-care diagnostics, and human-machine interface applications.

Electrochromism of Redox-Active Ionic Liquids and the Kinetics of the Colorations

Electrochromic (EC) devices have been gaining attention for display, electronic paper, and smart windows because of the low-power consumption, low-voltage drive, and memory effect of the colored state holding sharp contrast. They could be useful for the intended usage, which organic light emitting diode and liquid crystal display do not cover.The minimum components of EC devices are (i) redox-active EC material for a transparent electrode of interest, (ii) supporting electrolyte, (iii) medium (solvent), and (iv) charge-compensating (charge-balancing) redox material for another electrode. The medium (solvent) is required for electrolytes, which provide electric conductivity to the device. However, it is difficult to solve the problems of solvent evaporation and leakage of the electrolyte solution from the device. Recently, ionic liquids (ILs) are the focus of extensive investigations for electrochemical devices due to their non-volatility, moderate viscosity, and chemical stability. ILs can play roles of both solvent and supporting electrolytes. We have been focused on ILs as a designable liquid material with the above useful properties and developed electrochromic redox-active ionic liquids (RAILs).In RAILs, either or both constituent ions are redox-active. RAILs are a new class of ILs, which are non-volatile, electro-conductive, and viscous liquid materials. In addition, RAILs consist of concentrated redox-active ions, resulting in large redox density. In the case of RAILs with electrochromic ions, which are electrochromic RAILs (EC-RAILs), the concentrated electrochromic species give a large light absorption resulting in a very thin device thickness. The non-volatility and chemical stability provide the long-term durability of the EC devices. EC-RAILs play the roles of (i)-(iv) required in EC devices. In this study, we developed EC-RAILs, the coloration process by the voltage control, and their application to the EC devices without using solvents and supporting electrolytes. Because of the concentrated redox species and absence of the supporting electrolyte, the resistance of the EC cells could be dominant for the coloration kinetics.In this study, we have analyzed the electrode kinetics of the EC device composed of pure EC-RAILs.

Comparative Analysis of Thin and Thick MoTe2 Photodetectors: Implications for Next-Generation Optoelectronics.

Due to its outstanding optical and electronic properties, molybdenum ditelluride (MoTe2) has become a highly regarded material for next-generation optoelectronics. This study presents a comprehensive, comparative analysis of thin (8 nm) and thick (30 nm) MoTe2-based photodetectors to elucidate the impact of thickness on device performance. A few layers of MoTe2 were exfoliated on a silicon dioxide (SiO2) dielectric substrate, and electrical contacts were constructed via EBL and thermal evaporation. The thin MoTe2-based device presented a maximum photoresponsivity of 1.2 A/W and detectivity of 4.32 × 108 Jones, compared to 1.0 A/W and 3.6 × 108 Jones for the thick MoTe2 device at 520 nm. Moreover, at 1064 nm, the thick MoTe2 device outperformed the thin device with a responsivity of 8.8 A/W and specific detectivity of 3.19 × 109 Jones. Both devices demonstrated n-type behavior, with linear output curves representing decent ohmic contact amongst the MoTe2 and Au/Cr electrodes. The enhanced performance of the thin MoTe2 device at 520 nm is attributed to improved carrier dynamics resulting from effective electric field penetration. In comparison, the superior performance of the thick device at 1064 nm is due to sufficient absorption in the near-infrared range. These findings highlight the importance of thickness control in designing high-performance MoTe2-based photodetectors and position MoTe2 as a highly suitable material for next-generation optoelectronics.

Device physics of perovskite light-emitting diodes

Perovskite light-emitting diodes (LEDs) have emerged as a potential solution-processible technology that can offer efficient light emission with high color purity. Here, we explore the device physics of perovskite LEDs using simple analytical and drift-diffusion modeling, aiming to understand how the distribution of electric field, carrier densities, and recombination in these devices differs from those assumed in other technologies such as organic LEDs. High barriers to electron and hole extraction are responsible for the efficient recombination and lead to sharp build-up of electrons and holes close to the electron- and hole-blocking barriers, respectively. Despite the strongly varying carrier distributions, bimolecular recombination is surprisingly uniform throughout the device thickness, consistent with the assumption typically made in optical models. The current density is largely determined by injection from the metal electrodes, with a balance of electron and hole injection maintained by redistribution of electric field within the device by build-up of space charge.

Development of 3D-Printed Two-Compartment Capsular Devices for Pulsatile Release of Peptide and Permeation Enhancer.

The oral absorption of a peptide is driven by a high local concentration of a permeation enhancer (PE) in the gastrointestinal tract. We hypothesized that a controlled release of both PE and peptide from a solid formulation, capable of maintaining an effective co-localized concentration of PE and peptide could enhance oral peptide absorption. In this study, we aimed to develop a 3D-printed two-compartment capsular device with controlled pulsatile release of peptide and sodium caprate (C10). 3D-printed two-compartment capsular device was fabricated using a fused deposition modeling method. This device was then filled with LY peptide and C10. The release profile was modulated by changing the thickness and polymer type of the capsular device. USP apparatus II dissolution test was used to evaluate the impacts of device thickness and polymer selection on release profile in vitro. An optimal device was then enteric coated with HPMCAS. A strong linear relationship between the thickness of capsular devices and the delay in the release onset time was observed. An increase in the device thickness or the use of PLA decreased the release rate. The capsular device with compartment 1, compartment 2 and fence thickness of 0.4; 0.95 and 0.5mm, respectively, and the use of PVA achieved desired pulsatile release profiles of both peptide and C10. Furthermore, enteric-coated capsular devices with HPMCAS had similar pulsatile release profiles compared to non-enteric coated devices. These findings suggest potential application of 3D-printing techniques in the formulation development for complex modified drug release products.

Aqueous fibrous membrane electrolyte for ultrathin flexible Zinc-air batteries

Membrane electrolytes are key to constructing planar energy storage devices of low thickness and high flexibility, requesting simultaneous optimization of ionic conductivity and mechanical stability. Herein, aqueous phase electrospinning (APE) was implemented to co-spin polyvinyl alcohol and pullulan polysaccharide for fabricating crosslinked fibrous membrane electrolytes. While the hydroxyl-rich polymeric backbone grafted with quaternary ammonium endows a strong hydrogen-bonding network affording a large ionic conductivity of 30.2 mS cm−1, the cellulose-braced fibrous structure manifests a high tensile strength of 4.6 MPa. What’s more, the porous structure of the membrane electrolyte with enhanced charge mobility and uniformity helps to guide homogeneous Zn plating/stripping with suppressed dendrite growth. As a result, the assembled ultrathin flexible ZAB delivers a superb round-trip energy efficiency of 59.8 %, a maximum power density of 102 mW cm−2 and a long-term cycling stability over 100 h at 5 mA cm−2. By innovating the concept and methodology of aqueous fibrous membrane electrolytes, this study opens up a new chapter on the development of solid electrolytes in aqueous battery systems for powering wearable electronics.

Optimizing IOT Network Performance: A Study on Low-Power Wide-Area Network (LPWAN) Technologies for Smart City Applications

Abstract: This research explores with a specific focus on smart city applications, how to optimise the execution of Web of Things (IoT) networks by utilising breakthroughs in Low-Powered Wide Area Networks (LPWAN). As IoT devices proliferate and generate vast amounts of data, having a competent network becomes essential, especially when dealing with low device thickness and limited power availability. This analysis provides a detailed energy consumption model tailored to LoRaWAN, based on a deeper understanding of its functional components in Internet of Things scenarios. The review uses MATLAB for replication and looks at two clear scenarios: the standard allocation of spreading factors without optimisation and an improved method that uses particle swarm optimisation (PSO) for dynamic spreading factor work. The results show that the network energy consumption dropped significantly, from 6.3997×10^ (- 17) Joules to 2.5230×10^(- 17) Joules, along with increased throughput, decreased parcel misfortune, and decreased idleness. Through a detailed analysis of several parameters, such as network density and data transfer efficiency, this study demonstrates the feasibility of the suggested optimisation model in terms of improving battery efficiency and overall network performance. Finally, the findings demonstrate how efficient LPWAN systems may provide robust and useful IoT environments, which are essential for the successful implementation of smart city initiatives.

Interfacial Modification of ZnO/ZnMgO Bilayer for Efficient and Stable InP Quantum Dot Light-Emitting Diodes via Ultraviolet Ozone Treatment.

The development of efficient charge transport layers is crucial for realizing high-performance and stable quantum dot light-emitting diodes (QD-LEDs). The use of a ZnO/ZnMgO bilayer as an electron transporting layer (ETL) has garnered considerable attention. This configuration leverages the high electron mobility of ZnO and the favorable surface state of ZnMgO. Furthermore, the versatility of this configuration extends to its wide range of thickness tunability, rendering it suitable for the construction of thick devices for top-emitting structures with microcavities. However, despite the promising attributes of this bilayer configuration, the impact of the ZnO/ZnMgO bilayer ETL interface on QD-LEDs performance remains largely unexplored. Thus, this study investigated the effect of ultraviolet ozone (UVO) treatment on the stabilization of the ZnO/ZnMgO interface. UVO treatment was found to significantly enhance luminance uniformity across the QD-LEDs emission area while improving operational stability by over 4-fold. Comprehensive analyses employing X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy confirmed that UVO treatment significantly reduced the defect states of the hydroxyl groups and removed the insulating native ethanolamine ligands, thereby facilitating improved and uniform electron transport. Moreover, the effectiveness of UVO treatment in enhancing electron transport was supported by impedance analyses. Therefore, this paper presents an effective approach for enhancing the interface of a highly potent ZnO/ZnMgO bilayer ETL, which can ultimately improve the luminance uniformity and stability of QD-LEDs.

High Thickness Tolerance in All-Polymer-Based Organic Photovoltaics Enables Efficient and Stable In-Door Operation.

Organic photovoltaics (OPVs) have great potential to drive low-power consumption electronic devices under indoor light due to their highly tunable optoelectronic properties. Thick devices (>300nm photo-active junctions) are desirable to maximize photocurrent and to manufacture large-scale modules via solution-processing. However, thick devices usually suffer from severe charge recombination, deteriorating device performances. Herein, the study demonstrates excellent thickness tolerance of all-polymer-based PVs for efficient and stable indoor applications. Under indoor light, device performance is less dependent on photoactive layer thickness, exhibiting the best maximum power output in thick devices (34.7 µW cm-2 in 320-475nm devices). Thick devices also exhibit much better photostability compared with thin devices. Such high thickness tolerance of all-polymer-based PV devices under indoor operation is attributed to strongly suppressed space-charge effects, leading to reduced bimolecular recombination losses in thick devices. The unbalanced charge carrier mobilities are identified as the main cause for significant space-charge effects, which is confirmed by drift-diffusion simulations. This work suggests that all-polymer-based PVs, even with unbalanced mobilities, are highly desirable for thick, efficient, and stable devices for indoor applications.

The study of design and optimisation for CFRP combined pier anti-collision device

A CFRP honeycomb combination anti-collision device with a larger anti-collision level, greater crashworthiness, and longer service life was designed to safeguard the ship and piers in the event of an unintentional collision. Taking large-tonnage cargo ships and common bridge piers in the middle reaches of the Yangtze River as the research objects, the energy conversion response, impact force response and impact depth response of the collision were studied considering the collision conditions between the ship and the bare pier and the collision avoidance device. On this basis, the response surface method, variance analysis method and efficacy coefficient method were further used to take the shell thickness of the collision avoidance device and the thickness of the internal steel structure as the design parameters. The multi-objective optimisation design of the CFRP composite anti-collision device is carried out by selecting the ship impact force, the total internal energy absorbed by the anti-collision device, the total mass, and the inner diameter of the honeycomb steel structure as the optimisation objectives. The results show that the impact force reduction rate reaches 82.7%, the overall mass is greatly reduced, the maximum deformation is within a reasonable range, and the collision resistance is optimised.

Investigating the effect of SiO2 thin films with sculptured topographies on the alignment properties of liquid crystals

In the present work, sculptured thin films (STF) based on silicon dioxide (SiO2) induced on the indium tin oxide (ITO) coated substrates via glancing angle deposition (GLAD) technique using the physical vapor deposition (PVD) process. Our main motive to perform this work is to address the issues we have faced with the traditional alignment method and give a try to overcome those problems. Keeping these challenges in our mind, we are giving here an alternative to traditional method and explored this different alignment technique with GLAD process. We have fabricated a liquid crystal device (LCD) in a way of electrically-controlled birefringence (ECB) and placed the engineered substrates in anti-parallel alignment. Morphological, optical and electro-optic behaviour of resulting device has been studied in the ∼5 μm thick device. Effect of applied voltage on the morphology and electro-optic behaviour of liquid crystal has been established. Interestingly, LC material demonstrates electrically switchable birefringence colours viz. brown, green, pink, purple and mauve colour, under applied electric field in room temperature at 10X magnification under polarizing optical microscope. A very nice extinction and contrast has been obtained with fabricated ECB device, which elucidate the device quality with impeccable alignment without any disclination defects. Besides, the electro-optic characteristics it also shows a significant impact on the liquid crystal properties. The obtained results demonstrate nice optical retardation, a lower Frederick's threshold voltage i.e. 1.5 V and 19.03 dB higher contrast respectively. An impressive switching response time τon of 5.4 ms and τoff = 600 µs at 20 V has attained with respective device as well. Such change in parameters may correspond to the higher electrical torque experienced by the LC molecules on the application of applied field. Anchoring energy and pretilt angle of respective system has been calculated and correlated with observed behaviour. Thus, engineered device with this superior alignment method show remarkable electro-optic results which can open a new way for the development of fast LCD for advanced optical device applications.

SC-CNTs: Thin Film Transistors for High-Performance, Low-Power, Flexible Electronics

Single Walled Carbon Nanotubes (SWNTs) have gained a great deal of media attention over the past almost-two decades. From their theoretical usage as the foundational material for space elevators that would take travelers beyond earth’s atmosphere, to an active material that would allow engineers to create nanobots that internally repair or treat the human body, applications for SWNTs are numerous and have resonated within the imagination of scientists and the media alike. Fast forwarding to the modern era, we find that nanotubes still have a great deal of technological promise, some of which parallel those usages that were theoretically conceived many years ago.For over a decade, NanoIntegris Technologies Inc. has been at the forefront of synthesizing high-purity, electronically enriched SWNT’s and, during that time, has found that our materials have proven to transcend from the theoretical to practical-usage realm. With over 1,900 publications citing the usage of NanoIntegris’ high performance materials, we have not only seen the beneficial properties of our materials studied via techniques such as scanning electron microscopy but have also received many positive use-cases for our materials such as being an additive of highly-conductive, electrode (anode/ cathode) slurries of next-generation lithium-ion batteries, to being used as an active for the highly-sensitive detection of COVID antigens.Within my talk, I will display the usage of our high-purity semiconducting (≥99%) single walled carbon nanotubes to make the next generation of high-performance electronics. I will focus upon the usage of our IsoSol-S100 semiconducting solution that served as the spin-coated semiconducting layer within a short channel (<10 µm) thin film transistor with ON/OFF of 104, a device thickness of 400 nm, and a mobility of 39 cm2V-1s-1. I will further discuss the usage of our IsoNanotubes-S 99% solution to serve as the active material within a low-power, wearable Radio Frequency biosensor that covers the GSM spectra, with an operation frequency up to 2.1GHz, and that can serve as both a frequency multiplier and mixer.

Large-scale synthesis of defect-free phosphorene on nickel substrates: enabling atomistic thickness devices

Addressing the main challenges of defect-free, large-scale synthesis of low-dimensional materials composed of phosphorus atoms is essential for advancing promising phosphorene-based technologies. Using molecular dynamics simulation, we demonstrate the large-scale and defect-free synthesis of phosphorene on Nickel (Ni) substrates. We showed that substrate orientation is crucial in the controllable synthesis of different phosphorene allotropes. Specifically, blue phosphorene was successfully grown on Ni (111) and Ni (100) surfaces, while γ-phosphorene, referred to here as Navy phosphorene, was grown on Ni (110). In addition, temperature control (high temperature) and cooling rate (slow cooling) are also crucial in the formation of P6 hexagons. Finally, we report that the phosphorus pentamers (P5) are the essential precursor for phosphorene synthesis. This work provides a robust framework for understanding and controlling the synthesis of large-area, single-crystalline monolayer phosphorene.

Highly Efficient Ultraviolet Third-Harmonic Generation in an Isolated Thin Si Meta-Structure.

Nonlinear nanophotonic devices have shown great potential for on-chip information processing, quantum source, 3D microfabrication, greatly promoting the developments of integrated optics, quantum science, nanoscience and technologies, etc. To promote the applications of nonlinear nanodevices, improving the nonlinear efficiency, expanding the spectra region of nonlinear response and reducing device thickness are three key issues. Herein, this study focuses on the nonlinear effect of third-harmonic generation (THG), and present a thin Si meta-sructure to improve the THG efficiency in the ultraviolet (UV)region. The measured THG efficiency is up to 10-5 at an emission wavelength of 309nm. Also, the THG nanosystem is only 100nm in thickness, which is two-five times thinner than previous all-dielectric nanosystems applied in THG studies. These findings not only present a powerful thin meta-structure with highly efficient THG emission in UV region, but also provide a constructive avenue for further understanding the light-matter interactions at subwavelength scales, guiding the design and fabricating of advanced photonic devices in future.

Scalable Fabrication of Quasi-One-Dimensional van der Waals Ta2Pt3Se8 Nanowire Thin Films via Solution Processing for NO2 Gas Sensing over Large Areas.

Solution-based processing of van der Waals (vdW) one- (1D) and two-dimensional (2D) materials is an effective strategy to obtain high-quality molecular chains or atomic sheets in a large area with scalability. In this work, quasi-1D vdW Ta2Pt3Se8 was exfoliated via liquid phase exfoliation (LPE) to produce a stably dispersed Ta2Pt3Se8 nanowire solution. In order to screen the optimal exfoliation solvent, nine different solvents were employed with different total surface tensions and polar/dispersive (P/D) component (P/D) ratios. The LPE behavior of Ta2Pt3Se8 was elucidated by matching the P/D ratios between Ta2Pt3Se8 and the applied solvent, resulting in N-methyl-2-pyrrolidone (NMP) as an optimal solvent owing to the well-matched total surface tension and P/D ratio. Subsequently, Ta2Pt3Se8 nanowire thin films are manufactured via vacuum filtration using a Ta2Pt3Se8/NMP dispersion. Then, gas sensing devices are fabricated onto the Ta2Pt3Se8 nanowire thin films, and gas sensing property toward NO2 is evaluated at various thin-film thicknesses. A 50 nm thick Ta2Pt3Se8 thin-film device exhibited a percent response of 25.9% at room temperature and 32.4% at 100 °C, respectively. In addition, the device showed complete recovery within 14.1 min at room temperature and 3.5 min at 100 °C, respectively.

A novel automated thickness measurement method and device for nuclear fuel plates

The Nuclear and Energy Research Institute (IPEN-CNEN/SP) currently employs manual external u-shape frame micrometers with non-rotating spindles, and chamfered measuring anvils at 21 pre-defined points to control the thickness of its fuel plates. However, it is acknowledged that this method introduces the human element into the measurement process, potentially compromising result accuracy and the integrity of the fuel plates' surfaces. This research introduces a novel thickness measurement method and an accompanying automated device featuring precise movement mechanisms, data capture, transcription, and processing. Our findings emphasize the effectiveness of this new measurement system and the structural integrity of the equipment, highlighting its potential to significantly enhance both the speed and metrological reliability of dimensional control processes for nuclear fuel plates manufactured at IPEN-CNEN/SP.

[formula omitted] IO buffer with [formula omitted] devices considering hot-carrier and gate-oxide reliability issues

This paper presents circuit for 2×VDD signaling I/O buffer to solve the gate-oxide and hot-carrier reliability issues without consuming any active static power. The design is verified for a range of loads varying from 4 pF to 200 pF with operating speed ranging from 12 Mbps to 500 Mbps. The proposed circuit is implemented in 16 nm FinFET technology using 1.8 V thick gate devices. The design can be used in any CMOS technology for 2×VDD signaling I/O buffer to reduce hot-carrier effect and to avoid gate-oxide reliability issues.