A Novel Strategy for Preparing Stretchable and Reliable Biphasic Liquid Metal

Low‐melting liquid metal is a hugely promising material for flexible conductive patterns due to its excellent conductivity and supercompliance, especially low‐cost and environmental liquid processing technology. However, the ever‐present fluidity characteristic greatly limits the stable shape and reliability of prepared liquid metal conductive electronics. Herein, a novel solidification strategy of liquid GaIn alloys by Ni doping and heat treatment is first reported, which can efficiently create a solid phase in the liquid metal and provide an effective solution for practical applications. Particularly, the liquid characteristic is preserved for conveniently fabricating different flexible electronic circuits, and then the solidification is carried out on prepared conductive patterns by heat treatment. The solidification mechanism is revealed by the interface chemical reaction between Ni and GaIn, creating the solid phase of intermetallic compound (Ga₄Ni₃ and InNi₃) during heat treatment. Moreover, a biphasic GaInNi can be obtained by regulating the atomic ratio of gallium, indium, and nickel. As a result, the obtained GaInNi possesses extremely low sheet resistance (15 ± 4.5 to 135 ± 2.5 mΩ sq^?1) and the variation of ΔR/R₀ exhibits low level (0–2) when strained up to 100%, which offers a promising strategy to prepare stretchable and reliable liquid metal electronics.     

Solution‐Processed Extremely Efficient Multicolor Perovskite Light‐Emitting Diodes Utilizing Doped Electron Transport Layer

A specially designed n‐type semiconductor consisting of Ca‐doped ZnO (CZO) nanoparticles is used as the electron transport layer (ETL) in high‐performance multicolor perovskite light‐emitting diodes (PeLEDs) fabricated using an all‐solution process. The band structure of the ZnO is tailored via Ca doping to create a cascade of conduction energy levels from the cathode to the perovskite. This energy band alignment significantly enhances conductivity and carrier mobility in the CZO ETL and enables controlled electron injection, giving rise to sub‐bandgap turn‐on voltages of 1.65 V for red emission, 1.8 V for yellow, and 2.2 V for green. The devices exhibit significantly improved luminance yields and external quantum efficiencies of, respectively, 19 cd A^?1 and 5.8% for red emission, 16 cd A^?1 and 4.2% for yellow, and 21 cd A^?1 and 6.2% for green. The power efficiencies of these multicolor devices demonstrated in this study, 30 lm W^?1 for green light‐emitting PeLED, 28 lm W^?1 for yellow, and 36 lm W^?1 for red are the highest to date reported. In addition, the perovskite layers are fabricated using a two‐step hot‐casting technique that affords highly continuous (>95% coverage) and pinhole‐free thin films. By virtue of the efficiency of the ETL and the uniformity of the perovskite film, high brightnesses of 10 100, 4200, and 16,060 cd m^?2 are demonstrated for red, yellow, and green PeLEDs, respectively. The strategy of using a tunable ETL in combination with a solution process pushes perovskite‐based materials a step closer to practical application in multicolor light‐emitting devices.     

Boosting the Charge Transport Property of Indeno[1,2‐b]fluorene‐6,12‐dione though Incorporation of Sulfur‐ or Nitrogen‐Linked Side Chains

Alkyl chains are basic units in the design of organic semiconductors for purposes of enhancing solubility, tuning electronic energy levels, and tailoring molecular packing. This work demonstrates that the carrier mobilities of indeno[1,2‐b ]fluorene‐6,12‐dione ( IFD )‐based semiconductors can be dramatically enhanced by the incorporation of sulfur‐ or nitrogen‐linked side chains. Three IFD derivatives possessing butyl, butylthio, and dibutylamino substituents are synthesized, and their organic field‐effect transistors (OFET) are fabricated and characterized. The IFD possessing butyl substituents exhibits a very poor charge transport property with mobility lower than 10^?7 cm² V^?1 s^?1. In contrast, the hole mobility is dramatically increased to 1.03 cm² V^?1 s^?1 by replacing the butyl units with dibutylamino groups ( DBA‐IFD ), while the butylthio‐modified IFD ( BT‐IFD ) derivative exhibits a high and balanced ambipolar charge transport property with the maximum hole and electron mobilities up to 0.71 and 0.65 cm² V^?1 s^?1, respectively. Moreover, the complementary metal–oxide–semiconductor‐like inverters incorporated with the ambipolar OFETs shows sharp inversions with a maximum gain value up to 173. This work reveals that modification of the aromatic core with heteroatom‐linked side chains, such as alkylthio or dialkylamino, can be an efficient strategy for the design of high‐performance organic semiconductors.     

Virus‐Templated Self‐Mineralization of Ligand‐Free Colloidal Palladium Nanostructures for High Surface Activity and Stability

In solution‐based synthesis of colloidal nanostructures, additions of ligands, stabilizers, and redox reagents are generally required to obtain desirable structures, though ligands and stabilizers on the surface of nanostructures can substantially affect the surface‐related activity. Accordingly, an extensive rinsing process is usually required to remove residual reagents and stabilizers. This study reports a spontaneous self‐biomineralization of palladium (Pd) ions on a filamentous virus to form ligand‐free Pd nanowires under ambient conditions. No reducing reagents or additional surface stabilizers are used; the genetically modified virus alone supports the polycrystalline Pd nanowires within the nanostructure, maintaining the clean surface even without a rinsing process. The advantage of the ligand‐free Pd nanowires is found in the Suzuki‐coupling reaction, in which the nanowire catalytic activity is maintained after repeated reactions, while conventional Pd colloids undergo surface contamination by the stabilizer and lose their catalytic activity during repeated uses. The ligand‐free surface, high electronic connectivity, and structural stability of the Pd nanowires also allow high sensitivity and selectivity in hydrogen gas sensing analysis. This work emphasizes the importance of the ligand‐free surface of biotemplated nanostructures in maintaining functionalities without surface contamination.     

Analysis of a Parasitic‐Diode‐Triggered Electrostatic Discharge Protection Circuit for 12 V Applications

In this paper, an electrostatic discharge (ESD) protection circuit is designed for use as a 12 V power clamp by using a parasitic‐diode‐triggered silicon controlled rectifier. The breakdown voltage and trigger voltage (V_t) of the proposed ESD protection circuit are improved by varying the length between the n‐well and the p‐well, and by adding n+/p+ floating regions. Moreover, the holding voltage (V_h) is improved by using segmented technology. The proposed circuit was fabricated using a 0.18‐μm bipolar‐CMOS‐DMOS process with a width of 100 μm. The electrical characteristics and robustness of the proposed ESD circuit were analyzed using transmission line pulse measurements and an ESD pulse generator. The electrical characteristics of the proposed circuit were also analyzed at high temperature (300 K to 500 K) to verify thermal performance. After optimization, the V_t of the proposed circuit increased from 14 V to 27.8 V, and V_h increased from 5.3 V to 13.6 V. The proposed circuit exhibited good robustness characteristics, enduring human‐body‐model surges at 7.4 kV and machine‐model surges at 450 V.     

Novel Approach for Modeling Wireless Fading Channels Using a Finite State Markov Chain

Empirical modeling of wireless fading channels using common schemes such as autoregression and the finite state Markov chain (FSMC) is investigated. The conceptual background of both channel structures and the establishment of their mutual dependence in a confined manner are presented. The novel contribution lies in the proposal of a new approach for deriving the state transition probabilities borrowed from economic disciplines, which has not been studied so far with respect to the modeling of FSMC wireless fading channels. The proposed approach is based on equal portioning of the received signal‐to‐noise ratio, realized by using an alternative probability construction that was initially highlighted by Tauchen. The associated statistical procedure shows that a first‐order FSMC with a limited number of channel states can satisfactorily approximate fading. The computational overheads of the proposed technique are analyzed and proven to be less demanding compared to the conventional FSMC approach based on the level crossing rate. Simulations confirm the analytical results and promising performance of the new channel model based on the Tauchen approach without extra complexity costs.     

太赫兹量子级联激光器有源区有限元模拟

采用有限元分析法解决了太赫兹量子级联激光器(THz QCL)有源区模拟问题。由于InP基差频THz QCL有源区为千层纳米结构,无法拆分实验探索,因此模拟分析显得尤为必要。首先列出有源区量子结构的薛定谔方程,而后采用Galerkin有限元法改写薛定谔方程,再根据连续性和边界条件,得到本征值矩阵方程,最后采用Matlab写出运算程序求解本征值矩阵方程,求出波函数。针对不同有源区量子结构,设定材料、组分、厚度和周期数及外加偏压等参数,即可得到波函数模方、能级、频率和波长等模拟结果。选取InP基差频THz QCL结构进行验证,结果表明此模型切实可行,其拓展应用也可以解决GaAs THz QCL模拟问题。     

On the design of Robust‐WDM local area networks

Robust wavelength division multiplexing (Robust‐WDM) is a proposal to realize cost‐effective WDM local area networks (LANs) which can get around the expensive need for laser wavelength stabilization. The type of these networks that relies on an access protocol with aperiodic reservations and lenient‐token‐passing based control channel (the AR/LTP protocol) is promising. We look at the deployment of the AR/LTP analytical model in designing this type of network. The model is used to predict the effect of component and network parameters on the waiting time characteristics of the network. An increase in node operation times (i.e. receiver response time, transmitter select time and reservation period) would result in increasing the average waiting time of a connection request, but the waiting time is more sensitive to the physical span of the network and its size. It is also observed that increasing the inter‐reservation threshold may result in little increase in waiting time up to some limit beyond which delay increases rapidly. Copyright © 2001 John Wiley & Sons, Ltd.     

Amorphous Ta-nanocrystalline RuOx diffusion barrier for lower electrode of high density memory devices

The effects of the amount of RuO₂ added in the Ta film on the electrical properties of a Ta-RuO₂ diffusion barrier were investigated using n⁺⁺-poly-Si substrate at a temperature range of 650–800°C. For the Ta layer prepared without RuO₂ addition, Ta₂O₅ phase formed after annealing at 650°C by reaction between Ta and external oxygen, leading to a higher total resistance and a non-linear I-V curve. Meanwhile, in the case of the Ta film being deposited with RuO₂ incorporation, not only a lower total resistance and ohmic characteristics exhibited, but also the bottom electrode structure was retained up to 800°C, attributing to the formation of a conductive RuO₂ crystalline phase in the barrier film by reaction with the indiffused oxygen because of a Ta amorphous structure formed by chemially strong Ta-O or Ta-Ru-O bonds and a large amount of conductive RuO₂ added. Since a kinetic barrier for nucleation in formation of the crystalline Ta₂O₅ phase from an amorphous Ta(O) phase is much higher than that of crystalline RuO₂ phase from nanocrystalline RuO_x phase, the formation of the RuO₂ phase by reaction between the indiffused oxygen and the RuO_x nanocrystallites is kinetically more favorable than that of Ta₂O₅ phase.     

基于多孔硅光激荧光淬灭效应的SO2传感器

本文提出了用于大气环境中SO2含量监测的多孔硅(porous silicon）光学传感方法,该方法利用电化学浸蚀和UV光氧化后形成轻微氧化孔Si,所产生的表面膜对SiO2气体具有良好的敏感特性,本文依据SiOxHy/Si界面处的过渡态模型分析了该方法的传感原理,利用SEM和荧光光谱仪对UV 光氧化的多孔Si膜层性质及传感性能进行初步实验,取得预期研究结果。