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- 2018
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Effects of Nanowire Length on Charge Transport in Vertically Aligned Gold Nanowire Array Electrodes
摘要： In this study, we demonstrate that vertically aligned gold nanowire array electrodes provide rapid ion and electron transport to the electrode-electrolyte interface. The charge-transport properties of the nanowire electrodes were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy under a constant-volume device configuration. The total charge stored in the corresponding devices increases monotonically with the length of the nanowires owing to the concomitant increase in the electroactive real surface area of the electrode. A remarkable feature of the electrodes is that the internal resistance associated with charge transport decreases with increasing nanowire length. The electric double-layer capacitance per unit electroactive surface area remains constant up to high charge/discharge rates. Our results demonstrate that charge migration occurs rapidly on the surfaces of the nanowires regardless of their length and the charge/discharge rate used. Thus, vertically aligned nanowire array electrodes show promise as current collectors for next-generation electrochemical energy-storage devices.
关键词： energy storage,electric double-layer capacitance,current collector,battery,supercapacitor
更新于2025-09-10 09:29:36
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Effects of parasitic capacitance on both static and dynamic electrical characteristics of back-gated two-dimensional semiconductor negative-capacitance field-effect transistors
摘要： Negative-capacitance ?eld-e?ect transistors (NC-FETs) are a promising candidate for future low-power Internet of Things (IoT) applications. In this work, a uni?ed analytical drain-current model for back-gated two-dimensional (2D) NC-FETs has been proposed for both static and dynamic is calibrated to experimental data. E?ects of parasitic capacitance on both the static and dynamic electrical simulations, and this model characteristics of back-gated 2D NC-FETs are investigated systematically on the basis of the model. It is found that parasitic capacitance contributes to the reduction in subthreshold swing but leads to a larger dynamic hysteresis. Thus, a balance between both should be carefully taken into account.
关键词： Negative-capacitance ?eld-e?ect transistors,NC-FETs,dynamic hysteresis,subthreshold swing,parasitic capacitance
更新于2025-09-09 09:28:46
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Resolving ZnO-based coaxial core-multishell heterostructure by electrical scanning probe microscopy
摘要： Coaxially periodic ZnO/ZnMgO core-multishell nanowire (NW) heterostructures were grown via a metal organic chemical vapor deposition method. We investigated their electrical properties via the application of two locally resolved electrical scanning probe microscopy techniques, i.e., scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM), following a planarization process. As a result, ZnO and ZnMgO layers can be unambiguously distinguished by both techniques on NWs with diameters <1 lm and the smallest layer thickness of 10 nm, where a higher free carrier concentration along with a low resistivity is revealed for the ZnO regions in comparison to ZnMgO portions, as expected. This work demonstrates the high capability of SCM/SSRM as supplementary and effective tools for probing local electrical properties within functional complex quasi-1D heterostructures.
关键词： core-multishell nanowire,ZnMgO,ZnO,scanning spreading resistance microscopy,scanning capacitance microscopy
更新于2025-09-09 09:28:46
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Titanium coverage for plasma-induced uniform HfSiON film from Hf nanoscale islands on SiO <sub/>2</sub> /Si
摘要： Signi?cant improvement of the in-plane uniformity of an HfSiON ?lm is enabled by a Ti coverage over Hf islands on an SiO2/Si substrate. Surface diffusion of Hf during an HfSiON ?lm growth from Hf (island)/SiO2/Si structure induced by a nitrogen inductively coupled plasma (ICP) exposure is effectively suppressed by the Ti coverage. The nitrogen ICP exposure to the Ti/Hf (island)/SiO2/Si surface forms a TiN layer, which suppresses the surface diffusion of Hf by lowering the surface energy. Even a small Ti coverage of 5% is effective for the uniform Hf concentration in the HfSiON ?lm. The uniformity of the ?lm is monitored by an in vacuo noncontact AFM and a cross-sectional SEM imaging. An ex situ XPS analysis indicates that the TiN layer is sputtered by the ion bombardment and the Ti content in the ?lm decreases less than 1%. The intermixing of Si with Hf and the subsequent nitridation of the ?lm is successfully performed even the surface is covered with TiN. The mercury probe measurement revealed that the improved uniformity by the Ti coverage increases the capacitance and reduces the leakage current of the high-k dielectric ?lm.
关键词： uniform film,capacitance,HfSiON,Ti coverage,leakage current,nitrogen ICP,surface diffusion,plasma-induced,TiN layer
更新于2025-09-09 09:28:46
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The Balancing Act in Ferroelectric Transistors: How Hard Can It Be?
摘要： For some years now, the ever continuing dimensional scaling has no longer been considered to be sufficient for the realization of advanced CMOS devices. Alternative approaches, such as employing new materials and introducing new device architectures, appear to be the way to go forward. A currently hot approach is to employ ferroelectric materials for obtaining a positive feedback in the gate control of a switch. This work elaborates on two device architectures based on this approach: the negative-capacitance and the piezoelectric field-effect transistor, i.e., the NC-FET (negative-capacitance field-effect transistor), respectively π-FET. It briefly describes their operation principle and compares those based on earlier reports. For optimal performance, the adopted ferroelectric material in the NC-FET should have a relatively wide polarization-field loop (i.e., ”hard” ferroelectric material). Its optimal remnant polarization depends on the NC-FET architecture, although there is some consensus in having a low value for that (e.g., HZO (Hafnium-Zirconate)). π-FET is the piezoelectric coefficient, hence its polarization-field loop should be as high as possible (e.g., PZT (lead-zirconate-titanate)). In summary, literature reports indicate that the NC-FET shows better performance in terms of subthreshold swing and on-current. However, since its operation principle is based on a relatively large change in polarization the maximum speed, unlike in a π-FET, forms a big issue. Therefore, for future low-power CMOS, a hybrid solution is proposed comprising both device architectures on a chip where hard ferroelectric materials with a high piezocoefficient are used.
关键词： CMOS,negative-capacitance,piezoelectrics,field-effect transistor,MOS devices,power consumption,ferroelectrics
更新于2025-09-09 09:28:46
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Polyaniline based hybrid bionanocomposites with enhanced visible light photocatalytic activity and antifungal activity
摘要： Nickel doped polyaniline/cellulose bionanocomposites have been synthesized via in-situ polymerization of aniline and hydrothermally prepared nickel nanoparticles. The as prepared materials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Cyclic Voltammetry (CV) was used to determine the electrochemical surface area (ECSA) of the materials by using the electrochemical double layer capacitance (EDLC) data. SEM images reveal that synthesized nanocomposites contain spherical Ni nanoparticles scattered uniformly within PANI-Cellulose matrix. The as prepared materials exhibited significant degradation of reactive orange (RO-16) dye under visible light. Incorporation of Ni nanoparticles in to the polymer matrix causes strong adsorption of dye in case of PANI/C/Ni, PANI/Ni as compared to that of PANI. The photodegradation of RO-16 was achieved by the electron-hole pair separation and formation of reactive species by trapping of the photo generated electron from the surface of photo catalyst. Scavengers were added to identify the primary reactive species. Fluorescence spectroscopy was to study the recombination behavior of charge carriers (electron-hole pair) during photodegradation. Moreover, the anti-fungal nature of the bionanocomposites was also examined and the materials were found to be effective in growth control of two pathogenic fungal strains- Rhizoctonia solani and Alternaria alternate.
关键词： Visible light,Capacitance,Antifungal,Absorption,Nanoparticle,Electron-hole pair
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) - Budapest, Hungary (2018.8.26-2018.8.30)] 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) - Design Considerations of GaN Transistor Based Capacitive Wireless Power Transfer System
摘要： The paper discusses and evaluates design of capacitive wireless power transfer (WPT) system. The capacitive WPT can replace a conventional inductive WPT for example in applications where metallic objects are placed close to receiver or transceiver. Main limitation for wider application of the capacitive WPT is due to small coupling capacitance between two surfaces in limited space. Therefore, to utilize capacitive WPT system the switching frequency should be as high as possible. Challenges associated with design of capacitive WPT system operating in MHz range are discussed in this paper. In the paper it is described WPT system that consists of two copper plates to transfer power from the primary side to the secondary side. Some calculation considerations of resonant network is given in the paper. The high switching of inverter transistors requires high performance transistors with optimized driver circuit. The design of GaN transistor based inverter and driver circuit is discussed and experimental results are shown.
关键词： wireless power transfer,capacitance,electric field,high frequency inverter
更新于2025-09-09 09:28:46
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Touch sensor readout circuit with comparator threshold self-adjustment
摘要： This work describes a capacitive type touch sensor readout circuit using a current based capacitance-to-time converter with comparator threshold level self-adjustment. The proposed circuit generates an output pulse with duty-cycle corresponding to the panel capacitance variation using a simple switch control block, a current generator, and a comparator. This does not require additional ampli?ers and passive capacitors/resistors. As a result, the proposed scheme can lead to small size and low power on-chip solution with fast detection time compared to conventional touch sensor readout circuits. Furthermore, due to the comparator threshold level self-adjustment, the readout circuit is less sensitive to component mismatch and process variations. The readout circuit is implemented using CMOS 0.35 μm technology with core area of 100 μm × 27 μm and power consumption of 52 μW, which can detect the touch panel capacitance ranging from 5 pF to 50 pF.
关键词： capacitance-to-time converter,comparator threshold level self-adjustment,capacitive type touch sensor,smart user interface
更新于2025-09-09 09:28:46
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Porous Multilayered Films Based on poly(3,4- ethylenedioxythiophene) and poly(indole-5-carboxylic acid) and Their Capacitance Performance
摘要： Layer-by-layer (LBL) technique is a prevalent way to construct multilayered films. Herein, using high conducting poly(3,4-ethylenedioxythiophene) (PEDOT) and good stable redox-active poly(indole-5-carboxylic acid) (5-PICA), an alternately multilayered porous films has been prepared by the electrochemical LBL method. The alternately multilayered films were characterized by scanning electron microscope (SEM), cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscope (EIS) techniques. Compared with monolayered PEDOT (147.8 F g-1) and 5-PICA(198.3 F g-1), the PEDOT/5-PICA/PEDOT/5-PICA 4-layered film exhibited a higher specific capacitance which reached 281.7 F g-1 at 20 A g-1 in 1.0 M H2SO4 solution. Furthermore, the specific capacitance of 4-layered film still had good stability, viz., 73% retention after 1000 cycles at the range of potential -0.15 to 1.0 V and even reached 95% if the potential range was from -0.15 to 0.8 V. Therefore, these results indicated that the PEDOT/5-PICA/PEDOT/5-PICA was a potential electrode material for supercapacitors.
关键词： Specific capacitance,Layer-by-layer films,Electropolymerization,Conducting polymers
更新于2025-09-09 09:28:46
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Rapid detection of ultra-trace nanoparticles based on ACEK enrichment for semiconductor manufacturing quality control
摘要： Commercial fabrication of semiconductor circuits is currently conducted with nanometer resolution. As a result, trace amount of nanoparticles in semiconductor processing fluids have a great influence on the yield of semiconductor chips, which was only a minor problem in the past when semiconductors were processed at larger critical dimensions. Therefore, a highly sensitive and rapid method for the online detection of nanoparticles is highly sought after by semiconductor industry. The work presents a highly sensitive, easy to do, and rapid method for detection of nanoparticles in liquid, which is based on AC electrokinetics enhanced capacitive-sensing method using commercial microelectrode chips. The detection limit reaches as low as 0.1 part per trillion with a response time of 60 s. Testing conditions of AC voltage and frequency were also investigated to obtain the optimized test parameters. Compared with the other existing detection methods, this method is highly sensitive, of low cost and with a fast response, which is important to realize high-efficiency and -reliability quality control of semiconductor process.
关键词： Nanoparticle detection,AC electrokinetics,IC manufacturing,Capacitance sensing
更新于2025-09-09 09:28:46