共查询到20条相似文献,搜索用时 46 毫秒
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以钇稳定氧化锆(YSZ)为固体电解质,Pt作为电极材料,在不同温度下共烧制备了泵氧电极层原型。借助计时电流法和电化学阻抗谱(EIS)法,并结合SEM分析研究了共烧温度对泵氧电极性能的影响。结果表明,随着共烧温度的增加,泵电流先增大后减小,界面电阻先减小后增大,1 400℃共烧电极三相界面(TPB)最长,活性最强;随着共烧温度的增加,电极反应活化能略微降低。虽然1 400℃共烧电极活化能较1 450℃大,但由于其活性区域大,三相界面长,综合表现为1 400℃共烧电极催化活性最强。 相似文献
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Ichikawa S Akita T Okumura M Haruta M Tanaka K Kohyama M 《Journal of electron microscopy》2003,52(1):21-26
Three-dimensional (3-D) nanostructures of gold catalysts supported on TiO2 were analysed by electron holography and high-resolution electron microscopy. The contact angle of the gold particle on TiO2 tended to be >90 degrees in the case of gold particles with a size (height) of >4 nm and it tended to be <90 degrees for gold particles with a height of <2 nm. The change in morphology increases the perimeter at the Au/TiO2 interface as the particle size decreases. This change in 3-D structure should be attributed to a change in electronic structure at the interface. It was found that electron holography enabled 3-D analysis at the atomic level and was effective for analysing nanostructured particles. 相似文献
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Spectroscopic Indications of Tunnel Barrier Charging as the Switching Mechanism in Memristive Devices 下载免费PDF全文
Benedikt Arndt Francesco Borgatti Francesco Offi Monifa Phillips Pedro Parreira Thorsten Meiners Stephan Menzel Katharina Skaja Giancarlo Panaccione Donald A. MacLaren Rainer Waser Regina Dittmann 《Advanced functional materials》2017,27(45)
Resistive random access memory is a promising, energy‐efficient, low‐power “storage class memory” technology that has the potential to replace both flash storage and on‐chip dynamic memory. While the most widely employed systems exhibit filamentary resistive switching, interface‐type switching systems based on a tunable tunnel barrier are of increasing interest. They suffer less from the variability induced by the stochastic filament formation process and the choice of the tunnel barrier thickness offers the possibility to adapt the memory device current to the given circuit requirements. Heterostructures consisting of a yttria‐stabilized zirconia (YSZ) tunnel barrier and a praseodymium calcium manganite (PCMO) layer are employed. Instead of spatially localized filaments, the resistive switching process occurs underneath the whole electrode. By employing a combination of electrical measurements, in operando hard X‐ray photoelectron spectroscopy and electron energy loss spectroscopy, it is revealed that an exchange of oxygen ions between PCMO and YSZ causes an electrostatic modulation of the effective height of the YSZ tunnel barrier and is thereby the underlying mechanism for resistive switching in these devices. 相似文献
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Barbara Scherrer Meike V.F. Schlupp Dieter Stender Julia Martynczuk Jan G. Grolig Huan Ma Peter Kocher Thomas Lippert Michel Prestat Ludwig J. Gauckler 《Advanced functional materials》2013,23(15):1957-1964
The electrical conductivity of dense and nanoporous zirconia‐based thin films is compared to results obtained on bulk yttria stabilized zirconia (YSZ) ceramics. Different thin film preparation methods are used in order to vary grain size, grain shape, and porosity of the thin films. In porous films, a rather high conductivity is found at room temperature which decreases with increasing temperature to 120 °C. This conductivity is attributed to proton conduction along physisorbed water (Grotthuss mechanism) at the inner surfaces. It is highly dependent on the humidity of the surrounding atmosphere. At temperatures above 120 °C, the conductivity is thermally activated with activation energies between 0.4 and 1.1 eV. In this temperature regime the conduction is due to oxygen ions as well as protons. Proton conduction is caused by hydroxyl groups at the inner surface of the porous films. The effect vanishes above 400 °C, and pure oxygen ion conductivity with an activation energy of 0.9 to 1.3 eV prevails. The same behavior can also be observed in nanoporous bulk ceramic YSZ. In contrast to the nanoporous YSZ, fully dense nanocrystalline thin films only show oxygen ion conductivity, even down to 70 °C with an expected activation energy of 1.0 ± 0.1 eV. No proton conductivity through grain boundaries could be detected in these nanocrystalline, but dense thin films. 相似文献
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Young Beom Kim Timothy P. Holme Turgut M. Gür Fritz B. Prinz 《Advanced functional materials》2011,21(24):4684-4690
This paper reports both experimental and theoretical results of the role of surface modification on the oxygen reduction reaction in low‐temperature solid oxide fuel cells (LT‐SOFC). Epitaxial ultrathin films of yttria‐doped ceria (YDC) cathode interlayers (<10–130 nm) are grown by pulsed laser deposition (PLD) on single‐crystalline YSZ(100). Fuel cell current–voltage measurements and electrochemical impedance spectroscopy are performed in the temperature range of 350 °C ≈ 450 °C. Quantum mechanical simulations of oxygen incorporation energetics support the experimental results and indicate a low activation energy of only 0.07 eV for YDC, while the incorporation reaction on YSZ is activated by a significantly higher energy barrier of 0.38 eV. Due to enhanced oxygen incorporation at the modified Pt/YDC interface, the cathodic interface resistance is reduced by two‐fold, while fuel cell performance shows more than a two‐fold enhancement with the addition of an ultrathin YDC interlayer at the cathode side of an SOFC element. The results of this study open up opportunities for improving cell performance, particularly of LT‐SOFCs by adopting surface modification of YSZ surface with catalytically superior, ultrathin cathodic interlayers. 相似文献
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《Applied Superconductivity》1994,2(1):17-20
We have prepared high quality c-axis oriented superconducting YBa2Cu3O7−x thin films on Si(001) substrates covered with YSZ = (ZrO2 + 10 at.% Y2O3) layers by an in situ high pressure (3–5 mbar) oxygen d.c./r.f. sputtering process at substrate temperatures of about 750°C. The films were characterized by X-ray diffraction, transmission electron microscopy (TEM) and electron scanning (SEM) techniques. A superconducting transition temperature Tc(R− 0) = 89 K was determined by resistivity and susceptibility measurements. Cross sectional TEM analysis showed a sharp interface between YSZ and Si; however an inter diffusion zone was observed between YSZ and YBa2Cu3O7−x layers. 相似文献
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研究了采用单靶控溅射在Si(100)衬底上生长YSZ(钇稳定的ZrO2)BSCCO(铋锶钙铜氧)薄膜的工艺条件,包括生长温度,生长气氛,生长速率及氧化退化等。还研究了高温超导相的形成与生长温度的关系,并获得了超导膜临界温度为82K的BSCCO/YSZ/Si兼容材料。 相似文献
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Recently, electron holography has been successfully applied to analyze two-dimensional (2D) dopant distribution in semiconductor devices with high resolution and high sensitivity. The preparation of proper specimens is a fundamental step for the practical application of electron holography in the semiconductor industry. Therefore, it is important to explore a reliable and quick specimen preparation method. In our current work, we have tried to use the lift-out technique based on a focused ion beam, to fabricate cross-sectional CMOS device specimens for electron holographic observation. Using the lift-out technique, specimens with a large area and uniform thickness can be prepared directly from integrated circuit wafers in a very short time. Specimens with a complex and unknown dopant distribution were examined using off-axis electron holography. In the reconstructed phase images, the different 2D doping areas in a CMOS device, such as source, drain, well and substrate, were revealed successfully. The advantages and disadvantages of the technique are discussed. 相似文献
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K. A. Jones M. A. Derenge T. S. Zheleva K. W. Kirchner M. H. Ervin M. C. Wood R. D. Vispute R. P. Sharma T. Venkatesan 《Journal of Electronic Materials》2000,29(3):262-267
AlN films deposited on SiC or sapphire substrates by pulsed laser deposition were annealed at 1200°C, 1400°C, and 1600°C for
30 min in an inert atmosphere to examine how their structure, surface morphology, and substrate-film interface are altered
during high temperature thermal processing. Shifts in the x-ray rocking curve peaks suggest that annealing increases the film
density or relaxes the films and reduces the c-axis Poisson compression. Scanning electron micrographs show that the AlN begins to noticeably evaporate at 1600°C, and the
evaporation rate is higher for the films grown on sapphire because the as-deposited film contained more pinholes. Rutherford
backscattering spectroscopy shows that the interface between the film and substrate improves with annealing temperature for
SiC substrates, but the interface quality for the 1600°C anneal is poorer than it is for the 1400°C anneal when the substrate
is sapphire. Transmission electron micrographs show that the as-deposited films on SiC contain many stacking faults, while
those annealed at 1600°C have a columnar structure with slightly misoriented grains. The as-deposited films on sapphire have
an incoherent interface, and voids are formed at the interface when the samples are annealed at 1600°C. Auger electron spectroscopy
shows that virtually no intermixing occurs across the interface, and that the annealed films contain less oxygen than the
as-grown films. 相似文献
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分析了MZOS结构及其Si-SiO2子系统的C-V特性,发现ZnO中的氧空位和溅射工艺过程在Si-SiO2界面引入的界面电荷是影响MZOS结构界面特性的主要因素。研究还表明,低温热退火可以改善MZOS结构的界面特性。 相似文献
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McCartney MR 《Journal of electron microscopy》2005,54(3):239-242
Quantitative analysis of electrostatic potential in semiconductor device samples using off-axis electron holography in the electron microscope is complicated by the presence of charged insulating layers. Preliminary results indicate that the behavior of p-type material near the Si-insulator interface may differ from that of n-type if the insulator is charging. Coating one side of the sample surface with carbon usually eliminates charging effects. Holographic phase measurements on thin silicon oxide film at liquid nitrogen temperature indicates that the maximum electric field near the edge of an charged region is 18 MV cm(-1), on the order of the breakdown voltage. 相似文献
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Wen-Ting Sheng W. G. Wang X. H. Xiang F. Shen Fei-Fei Li T. Zhu Z. Zhang Zheng-Zhong Li Jun Du An Hu John Q. Xiao 《Journal of Electronic Materials》2004,33(11):1274-1279
We have used an electron holography (EH) technique to directly probe the potential profile of tunnel barriers in magnetic
tunnel junctions (MTJs). Barriers with under-, optimum-, or over-oxidized condition have been investigated. One important
finding is that there is always slight oxidation of the top electrode because of film morphology. Sharp interfaces can be
achieved in the bottom interface of optimally oxidized barrier or both interfaces in MTJs with under-oxidized barriers. We
also demonstrate, theoretically and experimentally, how barrier shape affects the bias dependence and, in low barrier height
case, result in inversed tunneling magnetoresistance (TMR) at high bias. The mechanism is very different from that responsible
for inversed TMR in all biases. The finding leads to the possibilities of achieving better signals at high bias in real applications. 相似文献
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热退火技术是集成电路制造过程中用来改善材料性能的重要手段。系统分析了两种不同的退火条件(氨气氛围和氧气氛围)对TiN/HfO2/SiO2/Si结构中电荷分布的影响,给出了不同退火条件下SiO2/Si和HfO2/SiO2界面的界面电荷密度、HfO2的体电荷密度以及HfO2/SiO2界面的界面偶极子的数值。研究结果表明,在氨气和氧气氛围中退火会使HfO2/SiO2界面的界面电荷密度减小、界面偶极子增加,而SiO2/Si界面的界面电荷密度几乎不受退火影响。最后研究了不同退火氛围对电容平带电压的影响,发现两种不同的退火条件都会导致TiN/HfO2/SiO2/Si电容结构平带电压的正向漂移,基于退火对其电荷分布的影响研究,此正向漂移主要来源于退火导致的HfO2/SiO2界面的界面偶极子的增加。 相似文献
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Today's information-oriented society requires high density and high quality magnetic recording media. The quantitative observation of fine magnetic structures by electron holography is greatly anticipated in the development of such new recording materials. However, the magnetic fields around particles <50 nm have not been observed, because the fields are too weak to observe in the usual way. Here we present a highly precise phase measurement technique: improved phase-shifting electron holography. Using this method, the electric field around a charged polystyrene latex particle (100 nm in diameter) and the magnetic field around iron particles (30 nm in diameter) are observed precisely. A precision of the reconstructed phase image of 2pi/300 rad is achieved in the image of the latex particle. 相似文献
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A textured tunnel oxide, TOPS, prepared by thermally oxidizing a thin polysilicon film on a Si substrate is reported. Due to the rapid diffusion of oxygen through the grain boundaries of the thin polysilicon into Si substrate and the enhanced oxidation rate at the grain boundaries, a textured Si-SiO2 interface is obtained. The textured interface results in localized high fields and enhances electron injection into TOPS. TOPS exhibits a higher electron injection efficiency, a better immunity to the electron trapping and interface state generation under high-field operation, and a higher asymmetric injection polarity than the normal oxide 相似文献
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本文利用高分辨电子显微术、电子能量损失谱和电子全息技术对Si基体上生长的SrTiO3(STO)和La0.9Sr0.1MnO3(LSMO)薄膜及其STO层和Si基体之间的界面结构进行了深入研究,结果表明在Si和STO层之间由于氧扩散会形成一层过渡的SiOx无序层,且随沉积条件不同界面原子无序层厚度稍有不同;选区电子衍射结果表明薄膜和基体之间的外延生长关系为[001]LSMO//[^-110]Si,[110]LSMO//[001]Si[001]STO,//[001]Si,[010]STO//[110]Si;电子能量损失谱分析表明界面无序层中Si离子的氧化态处于Si^2+和Si^0之间;电子全息结果清晰地显示了基体与薄膜之间存在明显的相位和势垒变化,负电荷聚集在界面SiOx的无序层中。 相似文献
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Jianxing Xia Junsheng Luo Hua Yang Fengjiao Zhao Zhongquan Wan Haseeb Ashraf Malik Yu Shi Keli Han Xiaojun Yao Chunyang Jia 《Advanced functional materials》2020,30(27)
In perovskite solar cells (PSCs), the interfaces of the halide perovskite/electron transport layer (ETL) and ETL/metal oxide electrode (MOE) always attract and trap free carriers via the surface electrostatic force, altering quasi‐Fermi level (EFq) splitting of contact interfaces, and significantly limit the charge extraction efficiency and intrinsic stability of devices. Herein, a graded “bridge” is first reported to link the MOE and perovskite interfaces by self vertical phase separation doping (PSD), diminishing the side effect of notorious ionic defects via both reinforced interface Ebi and the vacancies filling. Experimental and theoretical results prove that the inhomogeneous distribution of CsF in the bulk or surface of PC61BM would not only form metal–oxygen (M–O) dipole on MOE, reinforcing the interface Ebi, but also create a graded energy bridge to alleviate the disadvantage of band offset raised by the enhanced interface Ebi, which significantly avoid the carrier accumulation and recombination at defective interfaces. Employing PSD, the power conversion efficiency of the devices approaches 21% with a high open‐circuit voltage (1.148 V) and delivers a high stability of 89% after aging 60 days in atmosphere without encapsulation, which is the highest efficiency of organic electron transport layers for n–i–p PSCs. 相似文献