Analysis of frequency-dependent series resistance and interface states of In/SiO2/p-Si (MIS) structures

In this work, the investigation of the interface state density and series resistance from capacitance–voltage (C–V) and conductance–voltage (G/ω−V) characteristics in In/SiO₂/p-Si metal–insulator–semiconductor (MIS) structures with thin interfacial insulator layer have been reported. The thickness of SiO₂ film obtained from the measurement of the oxide capacitance corrected for series resistance in the strong accumulation region is 220 Å. The forward and reverse bias C–V and G/ω−V characteristics of MIS structures have been studied at the frequency range 30 kHz–1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the series resistance (R_s) and interface state density (D_it) values. Both the series resistance R_s and density of interface states D_it are strongly frequency-dependent and decrease with increasing frequency. The distribution profile of R_s–V gives a peak at low frequencies in the depletion region and disappears with increasing frequency. Experimental results show that the interfacial polarization contributes to the improvement of the dielectric properties of In/SiO₂/p-Si MIS structures. The interface state density value of In/SiO₂/p-Si MIS diode calculated at strong accumulation region is 1.11×10¹² eV⁻¹ cm⁻² at 1 MHz. It is found that the calculated value of D_it (≈10¹² eV⁻¹ cm⁻²) is not high enough to pin the Fermi level of the Si substrate disrupting the device operation.     

电容器工作时的热效应

本文用热力学第一定律给出电容器在工作时产生的热效应。     

A wire-form emitter metal–insulator–semiconductor tunnel junction

Physical effects arising due to change of configuration of a MIS system from planar to cylindrical, are theoretically analyzed. Attention is paid to the voltage partitioning and all the components of tunneling current. A simple simulation model is developed enabling prediction of the band diagram details and calculation of the currents. The trends expected with decreasing system radius are elucidated. Cylindrical geometry can be faced with when quantum wire is used as an electron emitter. Similar form may also be roughly attributed to an edge region of conventional MIS capacitors.     

电压反峰对脉冲电容器寿命特性的影响

以金属化聚丙烯膜电容器电压反峰为研究对象,探讨了脉冲电流对电容器寿命的影响机制,通过对电容器在不同电压反峰系数下进行寿命测试,研究了电压反峰系数与电容器寿命之间的关系。研究结果表明:当电压反峰系数在10%~65%时,电容器寿命成指数下降。基于试验结果,通过统计分析的方法,拟合出寿命随电压反峰系数变化的经验公式,可以用来预测不同反峰系数下金属化聚丙烯膜电容器的寿命特性。     

Graphene–Epoxy Flexible Transparent Capacitor Obtained By Graphene–Polymer Transfer and UV‐Induced Bonding

A new approach is reported for the preparation of a graphene–epoxy flexible transparent capacitor obtained by graphene–polymer transfer and UV‐induced bonding. SU8 resin is employed for realizing a well‐adherent, transparent, and flexible supporting layer. The achieved transparent graphene/SU8 membrane presents two distinct surfaces: one homogeneous conductive surface containing a graphene layer and one dielectric surface typical of the epoxy polymer. Two graphene/SU8 layers are bonded together by using an epoxy photocurable formulation based on epoxy resin. The obtained material showed a stable and clear capacitive behavior.

     

Electric Double‐Layer Capacitor Based on an Ionic Clathrate Hydrate

Herein, we suggest a new approach to an electric double‐layer capacitor (EDLC) that is based on a proton‐conducting ionic clathrate hydrate (ICH). The ice‐like structures of clathrate hydrates, which are comprised of host water molecules and guest ions, make them suitable for applications in EDLC electrolytes, owing to their high proton conductivities and thermal stabilities. The carbon materials in the ICH Me₄NOH ? 5 H₂O show a high specific capacitance, reversible charge–discharge behavior, and a long cycle life. The ionic‐hydrate complex provides the following advantages in comparison with conventional aqueous and polymer electrolytes: 1) The ICH does not cause leakage problems under normal EDLC operating conditions. 2) The hydrate material can be utilized itself, without requiring any pre‐treatments or activation for proton conduction, thus shortening the preparation procedure of the EDLC. 3) The crystallization of the ICH makes it possible to tailor practical EDLC dimensions because of its fluidity as a liquid hydrate. 4) The hydrate solid electrolyte exhibits more‐favorable electrochemical stability than aqueous and polymer electrolytes. Therefore, ICH materials are expected to find practical applications in versatile energy devices that incorporate electrochemical systems.     

Carbon materials for high-performance lithium-ion capacitor

As new-generation electrochemical energy-storage systems, lithium-ion capacitors (LICs) have combined the advantages of both lithium-ion batteries and supercapacitors, manifesting the merits of high-energy density under power density. Triggered by outstanding physicochemical characteristics and two different charge-storage mechanisms (including the Li⁺ insertion and electric double-layer capacitor characteristics), carbon materials have been intensively studied for fabricating high-performance LICs. However, the construction of high-performance LICs have been greatly limited by the unbalanced capacity and kinetic imbalance between the sluggish ion diffusion process of anode and fast electrostatic accumulation behavior of cathode. Thus, aimed at improving two different electrochemical storage performances, rational design of carbon materials has been summarized in this short review, which provide the directional guidance for engineering optimized carbon electrodes and become a breakthrough for improving energy/power densities of LICs. Furthermore, the prospects and unresolved scientific issues of LICs are also proposed.     

Hydrogen sensors based on metal-insulator-semiconductor structures with a layer of a proton-conducting solid electrolyte

Application of solid electrolytes as undergate layers accelerates the response of a sensor at room temperature as compared with ordinary hydrogen sensors manufactured on the basis of the metal-insulator-semiconductor (MIS) structures with a palladium gate. The proton-conducting solid electrolytes under study include NAFION, zirconium hydrophosphate, and etherified polyvinyl alcohol (PVA) with heteropolyacids and phenoldisulfonic acid, which can be deposited under the platinum gate. Sensors based on the MIS structures with these solid electrolytes show a high sensitivity toward hydrogen (～120 mV per concentration decade). The response time τ_0.63 of a freshly manufactured sensor with a layer of zirconium hydrophosphate amounts to about 2 min. The maximum mechanical stability, especially at relative humidities in excess of 80% is intrinsic to sensors containing layers of PVA with heteropolyacids. The response time of such sensors is nearly 10 min.     

企业情报管理信息系统的分析

本文运用系统工程的思想，现代化的管理知识和计算机网络技术，并结合实际课题的的研究，对企业情报ＭＩＳ的系统分析技术进行了有益的探讨．     

DSC of etched aluminum foils for use in electrolytic capacitors

A DSC method for evaluating the surface area of etched Al foils for use in high performance electrolytic capacitors is presented. A linear relationship between the etching degree (effective surface area) and the thermal resistance of the sample is obtained by means of DSC, based on the transient phenomenon. This method using the transient state in DSC measurement is not only novel, but also rapid and simple in evaluating the surface area of an etched aluminum foil. The method is effective even when the Al foil has a naturally oxidized surface.The authors wish to thank to Mr. Adachi and Mr. Koike of ELNA Co., Ltd. for supplying us with etched aluminum foils. This work is partially supported by the Research Fund of North Shore College of SONY Institute. R. O. whishes to express her gratitude to the support.