bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nondestructive Degradation Evaluation for Organic Coated Steels By Surface Potential Measurement
Authors: Katayama Hideki , Itou Sayaka , Akashi Takaya 
Published: February 2020

Organic coatings have been widely used for most steel structures as a cost-effective way for corrosion protection and ornamental design. Various methods have been suggested in order to check a degree of corrosion of organic coated metals. For example, visual observation and gloss measurement are well known as typical evaluation methods for organic coated metals.In this study, the corrosion performance of organic coated steels exposed to corrosive environment was estimated by surface potential measurement. In this study, the corrosion behavior of organic coated steels exposed to corrosive environment was monitored by surface potential measurement. In addition, the change in surface potential distribution was compared with the result of electrochemical impedance measurement in 0.5 M NaCl solution after measuring the surface potential.
Carbon steel of the size of 3cm x 5cm was used as a substrate, and the organic coated steel samples were prepared by spraying a clear acrylic lacquer coating. Wet-dry cyclic corrosion test was conducted by alternating the condition of adding 20μl droplet of 0.5M NaCl solution and drying at 293K and 40%RH.
After several cycles, a part of the surface exposed to corrosive environment showed lower potential than the other area. As the corrosion proceed, the change area grew up and the surface potential further declined. The electrochemical impedance characteristics also changed with an increase of wet and dry cycle number. The change in surface potential corresponds to that in the impedance characteristics, indicating that the deterioration process of the coated steel can be monitored by the surface potential measurement from the stage of the coating film deterioration.
Electronic Structure of Tantalum Oxide with Oxygen Vacancy and Polyvacancy, Oxygen Interstitial, Tantalum Interstitial and Tantalum Substituting Oxygen
Authors: Perevalov Timofey V. , Islamov Damir R. 
Published: February 2020

The electronic properties of Ta2O5 are limited by its defects. The defects are problem if Ta2O5 is used in DRAM or as a blocking layer in a flash charge trapping memory (CTM), because it leads to a high conductivity via the traps and the threshold voltage instability. On the contrary, the high defects concentration opens the possibility of using Ta2O5 as a storage medium in the CTM [1] and resistive random-access memory (ReRAM) [2]. The aim of the study is the investigation of the electronic structure of O vacancy (VO), O polyvacancy, interstitial O and Ta atoms, O-to-Ta substitution in Ta2O5 to clarify the trap nature responsible for the charge localization and transport. The simulations carried out for the λ-Ta2O5 [3] 168-atom supercell in terms of the DFT in Quantum-ESPRESSO code. The calculated bandgap of λ-Ta2O5 is 4.2 eV. All types of native defects, except for the O interstitial, form defect states into the λ-Ta2O5 bandgap. The value of trap thermal ionization energy 0.5 eV are comparable to the experimental ones 0.7-0.8 eV [4], and optical trap energy 0.9 eV for the VO indicate that the VO in Ta2O5 can act as the charge trap, and participate in charge transport. The width of density of states defect peaks indicate the charge localization in space. The electron localization on the VO in Ta2O5 is due to the polaronic effect. The negative charge distributed between the nearest Ta atoms and it reflects the bonding character of the Ta orbitals charge density. Its allows us to conclude that the chains of closely located oxygen vacancies in TaOx can act as a conductive shunt and participate in the resistive switching. Each subsequent O vacancy forms near the already existing one, and no more than 2 removed O atoms, related to Ta atom. The O polyvacancy forms a filled defective band in Ta2O5 bandgap.
The work is supported by the Russian Science Foundation grant #17-72-10103.
[1] K. Hota, F.H. Alshammari, K. N. Salama et. al, Acs. Appl. Mater. Inter. 9, 21856 (2017).
[2] M. Kim, S.R. Lee, S. Kim, M. Chang et. al, Adv. Funct. Mater. 25, 1527 (2015).
[3] H. Lee, J. Kim, S.J. Kim et. al, Phys. Rev. Lett. 110, 235502 (2013).
[4] V. Egorov, D.S. Kuzmichev, P.S. Chizhov et. al, Acs. Appl. Mater. Inter. 9, 13286 (2017).

Figure 1
(Invited) Apprehension of Large Coercive Field in Ferroelectric HfO2 Thin Films
Authors: Migita Shinji 
Published: February 2020

A special feature of ferroelectric HfO2 films is that they have large coercive fields (EC), as large as 1 MV/cm and more. A merit of the large coercive field is that a sufficient memory window is attainable even in ultrathin films. For example, a 2-V-memory window is available by 10-nm-thick Hf-Zr-O ferroelectric film. Compared with the conventional ferroelectric oxide capacitors using Pb(Zr, Ti)O3 and SrBi2Ta2O9 that applies around 100-nm-thick films, the ferroelectric HfO2 films contribute to the scaling of film thickness about one order. It is attractive for the development of high-density non-volatile memories integrated on LSI. On the other hand, the large coercive fields of ferroelectric HfO2 films bring serious concerns such as breakdown and endurance in capacitors. In this work, we studied the influence of large coercive fields on the endurance properties of Hf-Zr-O capacitors.
Metal-ferroelectric-metal (MFM) capacitors that consist of TaN/Hf-Zr-O/TaN were prepared on heavily doped Si substrates. TaN electrode films were deposited by DC sputtering, using Ta target and mixture gas of Ar and N2. Hf-Zr-O films were prepared by RF sputtering, using HfO2 and ZrO2 targets and Ar gas. The metal composition was adjusted to Hf : Zr=50 : 50, and the thickness is 10 nm. After deposition of the top TaN film, crystallization anneal was processed in a vacuum condition at 700 degree Celsius. Finally, top electrodes were patterned by photolithography and dry etching.
Ferroelectric properties of 10-nm-thick Hf-Zr-O capacitors were investigated by the polarization-voltage measurements. The ECvalue of this capacitor was evaluated to be 1 MV/cm. The electrical breakdown by the DC mode was measured to be about 4 MV/cm. Remnant polarization (Pr) and endurance properties of the capacitors are summarized in the figure. The Pr is faint when the applied electric field is less than the EC. The Pr value increases drastically when the electric fields are set between EC and 2xEC, and then gradually saturates over 2xEc. Thus a larger electric field is favorable for the achievement of large and stable polarization. In contrast, the endurance characteristics show a negative trend with the electric field. The endurance cycle as large as 108 was observed when the electric field is 2xEC, but it decreases drastically with the increment of electric field over 2xEC. It indicates that the capacitors are damaged even when the electric field is much lower than the breakdown field. Although a better endurance is expected at electric field lower than 2xEC, it makes a sacrifice of the Pr value and the stability. This trade-off relationship is considered to be a critical hurdle for the application of ferroelectric HfO2 capacitors.
This work was supported by JST CREST Grant Number JPMJCR14F2, Japan.

Figure 1
Nanomechanical Properties of ALD Hafnium Oxide (HfO2) on Silicon-on-Insulator (SOI) and Strained Silicon-on-Insulator (sSOI) Films
Authors: Mohammed Yousuf , Zhang Kai , Baumgart Helmut , Elmustafa A A 
Published: February 2020

Hafnium oxide is used as replacement for silicon oxide as a gate insulator in field-effect transistors [1]. HfO2 is used as a high-κ dielectric in DRAM capacitors and in advanced metal-oxide-semiconductor FET devices and in optical coatings [2].
Thin films of hafnium oxide (HfO2) were deposited by atomic layer deposition (ALD) on silicon-on-insulator (SOI) and benchmarked against strained-silicon-on-insulator (sSOI). Both types of films have been tested for surface morphology, crystal structure and nanomechanical properties. The nanomechanical properties have been tested using a nanoindenter from Keysight equipped with a three sided Berkovich diamond tip. The crystalline structure has been verified using X-ray diffraction. The surface morphology has been examined using atomic force microscopy (AFM) and the film thickness was verified using field emission scanning electron microscopy (FE-SEM) as indicated by the cross-sectional FE-SEM image as shown in Figure 1.
We will discuss the structural and mechanical properties of the films citing the superiority of the ALD technique that is particularly used in the fabrication of the films that are presented in this study.

References

Intel (11 November 2007). "Intel's Fundamental Advance in Transistor Design Extends Moore's Law, Computing Performance".

Zhu, C. Tang, L. R. C. Fonseca, and R. Ramprasad 47, 7399 (2012).

Figure 1
KPFM and XPS Metrology of Self-Assembled Monolayer Barrier for Copper Metallization
Authors: Ofek Almog Rakefet , Sverdlov Yelena , Kadan Kian , Burstein Larisa , Dagan Ronen , Shacham-Diamand Yosi 
Published: February 2020

Silane based Self assembled monolayer (SAM) has been demonstrated as a diffusion barrier layer on lowK dielectrics for sub 10 nm Cu interconnects for Integrated Circuit (IC) applications. A key problem in developing barrier layer is its monitoring capability, especially its thickness, uniformity, its coverage and defect density.
The aim of this work is to develop surface analysis methods for characterizing those variables providing in line monitoring techniques that can predict barrier quality and reliability. The approach presented in this paper was to examine the defect density and coverage properties of the SAM on LowK dielectric using physical methods for the characterization of monolayer thick films, i.e. Variable Angle X-Ray Photoelectron Spectroscopy (VA -XPS) and Kelvin Probe scanning Force Microscopy (KPFM).
The SAMs were deposited on three different substrates: bare-Si wafers, thermal oxide/Si and Low-k dielectrics on silicon wafers. The silanization was performed by chemical deposition from various solvents, both polar and non-polar, containing 1-2% silane in ethanol as a solvent at temperature range between 60oC to 120oC.
The deposited films where characterized as follows: Variable Angle XPS measurement of High Resolution Multiplex . Next, the XPS data was analyzed as follows: a plot of ln [𝑵𝒔𝒖𝒃 𝝀𝒔𝒖𝒃 𝑰𝒐)/(𝑵𝒐 𝝀𝒐 𝑰𝒔𝒖𝒃+1] Versus 1/sin(α) was drawn , where Nsub is the atomic number density for the substrate , No is the atomic number density for the overlayer, 𝝀𝒔𝒖𝒃 is the substrate Inelastic Mean free Path, 𝝀o is the overlayer Inelastic Mean free Path, Isub is the signal intensity of electrons coming from the substrate, Io is the signal intensity of electrons coming from the overlayer and α is the take of angle from the sample surface. The Thickness of the overlayer was calculated from the slope of the graph. Using that data thickness of the SAM was obtained. The method and results will be shown and compared to other methods such as TEM. The XPS data yielded average values on large areal spots (> 10-4 cm2).
To achieve high resolution analysis a Kelvin probe force microscopy (KPFM) were performed on SAM. KPFM gives a good image of SAM on low K material. We can learn a lot about Homogeneity and Coverage properties. A study of the nucleation and growth of the SAM, dependent on temperature and time was conducted. It seems that after 60 minutes, the SAM had the best homogeneity and surface coverage. (Figure 1).
After mastering the use of the two methods for SAM, the results are compared in order to find the most suitable method for SAM metrology and monitoring that can be employed by the Semiconductor industry.

Figure 1
Impact of Contact in Molecular Junctions: When Physics Dictates the Chemical Properties
Authors: Van Dyck Colin Jean-Louis , Bergren Adam Johan 
Published: February 2020

Molecular junctions are nanomaterials made of one molecule, or a thin organic layer, sandwiched between two metallic electrodes.[1] These systems are now widely and intensively studied due to a high potential for nanoelectronic applications. If these devices can now be reliably made and characterized, this field of research is facing a clear issue: the modification of the molecular structure offers a poor control over the device characteristics.
The basic idea of the design in Molecular Electronics is that the molecular level landscape in the junction will affect the electron transport, offering control over the current/voltage characteristics.[1-3] Driven by chemical intuition, the usual design of molecular junctions relies on electron donating or accepting building blocks. In this presentation, we show and explain that this approach which focuses on the isolated molecule properties provides a very limited or even erroneous picture as the contact of a molecule to two metal electrodes leads to a completely different entity.
Using first principle DFT calculations, we demonstrate that the contact of an asymmetric organic layer to metal electrodes comes with the creation of spontaneous and very intense electric fields in the junction.[4] The origin of this field are the permanent dipole moments in the junction. The built-in field completely modifies the energy landscape in the junction. We argue that only a design that takes into account such large contact renormalization effects could finally lead to the control of the electronic structure of molecular junctions and then move the molecular electronics effort in the intelligent design era.
[1] Aviram and Ratner, Chemical Physics Letters, “Molecular rectifiers”, 1974
[2] Van Dyck and Ratner, Nano Letters, 10.1021/nl504091v, 2015
[3] Van Dyck and Ratner, J. Phys. Chem. C, 10.1021/acs.jpcc.6b07855, 2017
[4] Van Dyck and Bergren, Accepted in Advanced Electronic Materials, “Large Built-in Fields Control the Electronic Properties of Nanoscale Molecular Devices with Dipolar Structures”, 2018

Figure 1
Atomic Scale Growth Processes of Thin Films As Revealed By Fast Surface X-Ray Diffraction
Authors: Shirasawa Tetsuroh , Voelgeli Wolfgang , Arakawa Etsuo , Takahashi Toshio , Matsushita Tadashi 
Published: February 2020

X-ray crystal truncation rod (CTR) scattering and reciprocal space mapping (RSM) are widely used to characterize the structure of thin films. The methods can provide the structural information, such as the atomic structure, shape and size of crystalline domain, and strain distribution, in any ambient conditions without destructing the specimen. The use of the methods is often limited in the static structure analysis, because the acquisitions of CTR scattering profile and RSM dataset are often time consuming (mins to hrs).
Our group has developed a method that can measure a wide range of CTR profile and RSM in a single acquisition by using an energy-dispersive converging X-rays [1]. The technique allows the in-operando observation of atomic scale processes of photo-induced surface phenomenon [2] and electrochemical processes at the solid-liquid interface [2] with a time resolution of 1 s. The time frame is also reasonable to study the thin film growth processes.
In this contribution talk, we show the atomic scale growth processes of ultra thin films, Bi and Bi2Se3, as reveled by the energy-dispersive surface X-ray diffraction. In the growth of Bi film, we observed: the formation of wetting atomic layer at the interface, the growth of black phosphorous phase, which does not exists in bulk, below the thickness of ~2 nm, and the growth of bulk Bi structure in the upper layer. In the growth of Bi2Se3 film, we observed a strained Bi2Se3 structure in the first a few Bi2Se3 layers. The relationships between the growth behaviors and the electronic properties, namely, the quantum confinement effect in Bi and the topological phase transition of Bi2Se3, are discussed.
[1] T. Matsushita, T. Takahashi, T. Shirasawa, E. Arakawa, H. Toyokawa, and H. Tajiri, J. Appl. Phys. 110, 102209 (2011).
[2] T. Shirasawa, W. Voegeli, E. Arakawa, T. Takahashi, and T. Matsushita, J. Phys. Chem. C 120, 29107 (2016).
[3] T. Shirasawa, T. Masuda, W. Voegeli, E. Arakawa, C. Kamezawa, T. Takahashi, K. Uosaki, and T. Matsushita, J. Phys. Chem. C 121, 24726 (2017).
Anion Radical Mediated High Capacity Redox Flow Battery
Authors: Nanda Jagjit , Self Ethan Craig , Ruther Rose E. , Delnick Frank M. 
Published: February 2020

The energy density of conventional redox flow batteries (RFBs) is dictated by their capacity (which is directly related to the solubility of the redox species in the electrolyte) and operating potential. RFBs have low operating potentials ca. 1.5 V, resulting in poor energy densities (25 – 30 Wh/kg for an all vanadium RFB), whereas systems containing organic electrolytes with wider electrochemical windows can potentially have moderately higher energy densities. A new approach to improve the performance of nonaqueous redox flow batteries (RFBs) through electrochemically-mediated reactions is demonstrated. Soluble anion radical species (biphenyl and pyrene) mediate reversible sodium storage in a red phosphorus anode located in an external plug flow reactor in the absence of binders or conductive additives. Because the anion radical species can be recycled several times throughout the cell stack during a single charge/discharge cycle, a mediated RFB effectively decouples the battery’s energy density from the redox species’ solubility in the electrolyte. Furthermore, this technology offers inherently safe operation and is unaffected by the large volume changes of red P (>300%) due to the use of an external plug flow reactor. This presentation will describe the mechanism of a mediated RFB and discuss important design considerations (e.g., selection of appropriate electrolyte, mediators, active materials, etc.). Results showing electrochemically mediated sodiation and desodiation of a phosphorus anode in a redox flow configuration will be presented
This work is supported by Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy and The Office of Electricity Delivery and Reliability, U. S. Department of Energy.
Semi-Solid Hypervalency Based Li-S Battery Electrolytes
Authors: Navarro-Suárez Adriana M. , Johansson Patrik 
Published: February 2020

The urge for electrochemical energy storage devices with high gravimetric and volumetric energy density is imminent and the lithium−sulfur (Li-S) battery has been poised as a major next generation battery concept candidate. While it has a (very) high theoretical energy density, low cost and non-toxicity of starting materials,[1] its practical application has been hampered by several obstacles; the active material(s) elemental sulfur (S8) and lithium sulfide (Li2S) are both electronic insulators, polysulfides dissolve into the electrolyte and diffuse between the cathode and anode – generating an active material loss, there are dendrites formed at the lithium metal anode, etc.[2,3]
To address (some of) these problems, the solubility properties of the electrolyte are of utmost importance [4] and here we use semi-solid electrolytes – materials without flow but malleable – to hinder the dissolution of sulfur and possibly also mitigate the creation of lithium dendrites. These electrolytes are composed of matrices of hypervalent molecules i.e. with large internal dipole moments, heavily doped with Li-salts to generate Li+ conduction paths via percolation networks.[5] We report on initially assessed physico-chemical properties, basic electrochemical properties such as ion conductivity (Figure 1), before progressing to feasibility tests in Li-S battery cells.
This work was funded by “Batterifondsprogrammet” of the Swedish Energy Agency.
Figure 1. Arrhenius plots of two different hypervalency based electrolytes and the matrix used.

Reference
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[1] Q. Pang, X. Liang, C.Y. Kwok, L.F. Nazar, Nat. Energy 1 (2016) 16132.
[2] X. Judez et al., J. Electrochem. Soc. 165 (2018) A6008–A6016.
[3] J. Scheers, S. Fantini, P. Johansson, J. Power Sources 255 (2014) 204–218.
[4] S. Drvarič Talian, S. Jeschke, A. Vizintin, K. Pirnat, I. Arčon, G. Aquilanti, P. Johansson, R. Dominko, Chem. Mater. 29 (2017) 10037–10044.
[5] T. Mizumo, R. Fujita, H. Ohno, J. Ohshita, Chem. Lett. 40 (2011) 798–800.

Figure 1
Co-Deposition of Catalytic Pt-Rh Thin Films in the Self-Terminated Regime
Authors: Ambrozik Stephen , Dimitrov Nikolay , Moffat Thomas P. 
Published: February 2020

The drive to adopt alternative energy technologies for a more sustainable energy future has been inhibited by insufficient activity, poor durability and high cost of fuel cell catalysts. To overcome these drawbacks there has been significant interest in the exploration of core-shell nanoparticles, related overlayer thin films and alloy architectures. These bimetallic systems offer significant tunability based on ligand effects associated with nearest neighbor bonding 1, strain effects associated with lattice mismatch between the constituent metals , and geometric effects dictated by the local atomic distribution of elements. In order to realize such effects significant effort is underway to develop inexpensive, easy fabrication methods for forming these alloy and over-layer architectures 2-7.
Recently, self-terminated electrodeposition reactions have been discovered and adopted for the fabrication of ultra-thin metal films with monolayer level control 8-11. For the electrodeposition of Pt and/or Ir on Au and Ni12 the deposition of growing metal at high overpotentials is quenched at the onset of hydronium reduction by hydrogen adsorption. In this work, the electrodeposition of Pt-Rh alloys at potentials coincident with hydronium reduction will be discussed. In contrast to Pt, the electrodeposition of Rh is not terminated by hydrogen adsorption. The introduction of minimal quantities of [RhCl6]3- into the NaCl-[PtCl4]2- electrolyte disrupt the quenching of the Pt partial deposition reaction. The impact of Rh concentration on deposition rate, film morphology and composition was examined with voltammetry, SEM, XPS, and ISS. Finally, the tunability of as deposited films of varied thickness and composition toward the ethanol oxidation reaction will be discussed.
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