bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Broadband Spectroscopic Characterization of Electrically Active Defects in Dielectrics: Monitoring the in-Service Evolution of Dialectics in Integrated System
Authors: Obeng Yaw S. , Okoro Chukwudi A , Amoah Papa K. , You Lin 
Published: February 2020

Emerging nanoelectronics are been hindered by reliability challenges such as stress related failures. The stress buildup is due primarily to mismatch in the coefficient of thermal expansion (CTE) of the materials of construction which results in the generation of defects such as cracks, voids, delamination, plastic deformation, substrate warping and buckling. These types of damage ultimately lead to open or short circuits in the devices, resulting in catastrophic failure. The chemistry and physics of the materials also play crucial roles in the changes in the stress over time, especially in low operating voltage devices. The process flows of such low voltages devices entail low temperatures processing, and the use of low temperature deposited dielectrics, such as low-k materials, plasma deposited and sub-atmospheric pressure deposited films derived from organometallic precursors as insulators between metal lines and layers. Unfortunately, these low-temperature-processed materials are metastable due the presence of reactive metastable intermediates from the cracking of the precursors, and incomplete reactions within the films that result in electrically active defects in the “as deposited” films. Metrology is thus needed for the accurate quantification of the reliability impact of stress evolution in such integrated systems. Unfortunately, traditional spectroscopic tools, such as infra-red (FTIR), ellipsometry, electron spin resonance (ESR), solid state nuclear magnetic resonance (NMR), XRD, etc. which do not accommodate integrated devices. Microwave (RF)-based metrology tools are uniquely suitable for studying the buried structures and interfaces inherent in such nanoelectronic devices.
In this paper, we discuss the use of broadband radio waves (RF) (with frequencies up to 20 GHz) to detect, characterize and monitor the evolution of active defect in low-temperature processed dielectric films as a result of deliberate thermal exposure. The impact of thermal anneal on the behavior of the electrical defects shed light on the chemical changes occurring within the dielectric films that lead to changes in stress buildup.
3-D Extension of Chemical Mechanical Polishing for Nano-Structuring Applications on Alternative Technologies
Authors: Ozdemir Zeynep , Basim G. Bahar 
Published: February 2020

Chemical mechanical polishing has long been adopted as a technique to enable global planarization for semiconductor applications. The main functional requirements such as selectivity, enhanced material removal rates and minimal defectivity are achieved through advanced slurry formulations and process set up. In this study we tune the CMP process to generate controlled nanostructures to benefit from the synergy it enables on metallic surfaces namely; (i) formation of a protective metal oxide film during polishing and (ii) ability to tune the root mean square surface roughness from nano to micro scale.
The first application is on titanium surfaces to modulate the surface structure of the implantable biomaterials. We have demonstrated earlier that the CMP application on dental implants have improved the in-vitro biocompatibility with 3-D applications being developed [1]. The application we propose in this study is the application of the CMP induced nano-structuring for the lime-scale prevention on the heating elements. Lime scale formation by the hard water often causes numerous technical and economic problems in industrial and house-hold equipment. In scope of the work bare stainless steel and alternative coating materials were characterized for surface roughness, surface energy and wettability responses in order to observe the CMP induced nanostructure levels on the CaCO3 attachment behavior. Surface topography was evaluated through atomic force microscopy (AFM) on all the materials after CMP process was conducted. Accelerated lime scale formation tests were performed on these surfaces and the affect of random nanostructures and their thermal expansion abilities as live nanostructures were evaluated on the exfoliation of the lime scale. From the experimental work surface total energy was observed to be one of the main indicators for the lime scale adhesion prevention [2]. Figure 1 shows the calcination removal performances of the alternative coating elements as compared to the steel after the heat cycle the heating elements are exposed to..
References

Ozdemir Z., Orhan O., Bebek O., Basim G. B., Development of 3-D Chemical Mechanical Polishing Process for Nanostructuring of Bioimplant Surfaces, ECS Transactions, 2014, 61, 21-26.

Basim G.B.,Chemical Mechanical Polishing Induced Live Nano-Structures for Lime-Scale Prevention on Heating Elements. International Patent Office Application No: PCT/TR2013/000378, Application Date: 31.12.2013.

Figure 1
(Invited) Nanostructures Growth By Oxidation of Metallic Alloy Thin Films with Atmospheric Pressure Remote Plasma
Authors: Imam Abdallah , Gries Thomas , Hussein Khaled , Amati Mateo , Belmonte Thierry 
Published: February 2020

During the last decade, research on metal oxide nanostructures has led to the emergence of new materials with unique physical and chemical properties. In this work, we report on a process based on an atmospheric pressure micro-afterglow to synthesize oxide nanostructures of copper-iron alloy thin films deposited by magnetron sputtering. In plasma afterglow processes, active species like oxygen atoms or metastable states of oxygen are available. They are more active than ground state oxygen at low temperature because of the extra amount of energy coming from dissociation or excitation. Oxidation of metals in these conditions promotes the growth of oxide nanostructures.
The effect of the addition of copper to iron (and vice versa) is investigated by creating either alloys single layers or stacks of copper and zinc layers with different thicknesses on a glass substrate. The experimental device consists in using an Ar-O2 microwave plasma. Active species exit the reactor through a tiny hole (500 µm in diameter) and react with the copper-iron film to perform the direct synthesis of oxide nanostructures in a single step without any template or surfactant. The morphology, shape and size distribution can be controlled by varying the experimental parameters such as the amount of oxygen injected in the plasma, the microwave power, the treatment time or the alloy composition. It appears possible to synthesize different kinds of nanostructures with good reproducibility in a single-step process: nanowires, nanowalls or nanoblades. Various characterization means, including SEM, SIMS, TEM and XRD were used to determine the composition of the nanostructures. Besides, XPS microscopy experiments were carried out with the SPEM at the spectroscopy for chemical analysis (ESCA) microscopy beamline at the Elettra synchrotron facility in Trieste. We show that both oxides, CuO and Fe2O3, can be formed on the same spot (see figure). Furthermore, by controlling the composition of the alloy, we show that very thin CuO nanowires (with diameters as small as 5 nm) can be grown. Ultra-thin nanoblades of Fe2O3 can be formed. They are so thin than their edge is submitted to grow instabilities and become serrated.
The formation mechanism of these structures was investigated. The role of the addition of a new element on the growth mechanism, together with the way it is distributed within the stack, will be discussed. The role of stress on grain size, grain boundaries and outward diffusion of metallic ions will be discussed. Results will be compared to those obtained by different groups via thermal oxidation. Finally, a growth model will be proposed to explain the synthesis of the as-grown nanostructures.

Figure 1
Plasma Etching Chemistry for Smoothening Ofultrananocrystalline Diamond Films
Authors: Sunkara Mahendra Kumar , Jaramillo-Cabanzo Daniel Felipe , Willing Gerold 
Published: February 2020

Ultrananocrystalline diamond (UNCD) is characterized by the dimensions of its ultra-nanoscale grains and is typically synthesized under high nucleation conditions using an argon-rich hydrogen/methane/argon gas mixture. UNCD films consist of crystalline grains of at least 95% sp3-bonded carbon that are 2-10 nm in size with a surface roughness ranging between 20 and 40 nm. UNCD films exhibit most of the outstanding properties of diamond such as an exceptional hardness, high mechanical strength, extremely low friction coefﬁcient, chemical inertness, thermal stability and high electrical conductivity at room temperature when doped with nitrogen. While all these properties are intrinsic of the material, the required roughness scale of the UNCD film needs to be carefully tailored and customized on an application-by-application basis. For instance, a low roughness is key to manufacturing adequate micro-electromechanical systems (MEMS), wear-resistant low friction coatings, X-ray lithography masks and biomedical devices where stringent tolerance and topological precision are of utmost importance.
Here, a new process for controlled smoothening of ultrananocrystalline diamond films using H2/O2 plasma is presented. Diamond films were exposed to oxygen, hydrogen and hydrogen/oxygen mixture (19:1) plasmas. Evolution of morphology and thickness were monitored ex-situ using scanning electron microscopy (SEM) while roughness was measured using atomic force microscopy (AFM). Neither pure oxygen nor pure hydrogen plasmas were found suitable for smoothening the films. The H2/O2 mixture plasma exposure resulted in a constant roughness decrement of 0.043 nm/min with a slow etching rate (0.07 µm/h) allowing for the control of the final film roughness without sacrificing too much of the material thickness.
Recent Attempts to Improve the Capabilities of Commercial CFx to Enhance the Efficiency of Li/CFx Batteries
Authors: Meshri Dayal T. , Shembel Elena M , Meshri Sanjay D. , Adams Robert L. , Mathur N.C. , Pinnapareddy Devender , Redko Vlad I , Maksyuta Irina M , Markevich Alexandr V 
Published: February 2020

Lithium/CFx batteries have long storage life and have wide applications in various fields from space exploration to medical electronics. Lithium/CFx battery shows highest theoretical capacity when compared to other primary batteries such as Li/SOCl2 and Li/MnO2 batteries. However, Li/ CFx batteries suffers from voltage delay, show lower open circuit voltage during initial discharge and do not perform well in high rate applications which may be due to intrinsically poor electronic conductivity of CFx cathode material Historically, while making the cathode, addition of carbon is done to improve the material conductivity and get a better performance but it decreases the discharge capacity.
Recently, many attempts have been made to improve efficiency of Li/CFx batteries by modifying CFx properties through various physical and chemical means from coating carbon on CFx surface to mechanochemical and chemical treatment. Use of some of these modified CFx resulted in improved battery performance that included no voltage delays, better operating voltage and higher rate capabilities in comparison to standard Li/ CFx batteries.
In this paper, development of CFx from historical perspective to the present day will be briefly discussed. We shall also present a short review on the recent attempts made by us and various other groups to modify properties of CFx for Li/CFx batteries. Use of modified CFx looks very promising for improving the efficiency of Li/CFx batteries.
Modelling Li-S Cells: Mechanisms behind Voltage- and Capacity-Drop during Discharge
Authors: Zhang Teng , Marinescu Monica , Wild Mark , O'Neill Laura , Offer Greg 
Published: February 2020

The lithium-sulphur (Li-S) cell could provide the next step-change in battery technology with a promising practical energy density of 500-600 Wh/kg. However, a lack of understanding of the complex electrochemical, transport, and phase-change phenomena in Li-S cells is arguably holding back development. Acquiring this knowledge requires experimental characterizations in tandem with mechanistic modelling. In this presentation, we point out that existing Li-S models do not sufficiently capture the voltage- and capacity-drop mechanisms of Li-S cells during discharge. We first demonstrate that introducing a concentration dependence of the electrolyte conductivity is necessary to retrieve the experimentally documented trends in electrolyte resistance, which contributes to a major voltage-loss mechanism for high-energy density Li-S cells. We further illustrate the existence of an often overlooked potential drop mechanism – the ‘precipitation overpotential’ – which originates from the limited rate of lithium sulphide precipitation. In addition, we propose that the rate capability of high energy-density Li-S cells is mainly limited by the slow transport of ionic species, as is evident from the good agreement between experimental and model-predicted capacity loss at high discharge currents as well as a cell capacity recovery phenomenon that we report for the first time.
References:
T. Zhang, M. Marinescu, M. Wild, L. O’Neill, and G. Offer, Phys. Chem. Chem. Phys.
17, 22581 (2015).
M. Marinescu, T. Zhang, G. Offer, Phys. Chem. Chem. Phys., 2015, advance article.
Utilising Shiners for the Study of Oxygen Electrochemistry in the Lithium-Oxygen Battery
Authors: Galloway Tom , Ball Sarah , Copley Mark , Hardwick Laurence J 
Published: February 2020

Understanding the fundamental reaction mechanisms in the lithium oxygen battery is a key step in the development of a stable electrolyte. Surface enhanced Raman spectroscopy (SERS) is a non-destructive and non-invasive technique; it can be used to investigate the chemical bonding of surface species, making it a very valuable technique to study in situ the oxygen reduction and evolution reactions taking place at the liquid-solid interface. However the Raman signal is inherently weak. The signal can be enhanced by roughening the cathode surface, using an electrochemical oxidation/reduction cycle (ORC)1. By studying the oxidation reduction/evolution reaction within dimethyl sulfoxide based electrolytes on SERS active gold; the presence of both superoxide (O2
-) and lithium peroxide (Li2O2) has been observed at the interface2. SERS however is limited to precious metal surfaces.
Unlike SERS the use of SHINERs (shell isolated nanoparticles for enhanced Raman spectroscopy3) (figure 1) is not restricted to precious metal surfaces. Adding a near-monolayer of SHINERS can enhance the Raman signal by ca. 108. The gold nanoparticle has a strong electromagnetic field which enhances the Raman signal, whilst the SiO2 shell inhibits any catalytic effect from the gold core. SHINERs can therefore enhance a variety of surfaces, such as carbon, which have been previously very challenging to analyse.

In situ studies with SHINERS without the presence of lithium have been able to track the reaction mechanism on planar, glassy carbon, gold, palladium and platinum surfaces, with the reduction and oxidation of free O2
- observed. Further studies on glassy carbon in the presence of lithium have detected lithium superoxide (LiO2) and lithium peroxide (Li2O2) species in MeCN and DMSO electrolyte media’s. We are continuing to further develop this technique within non-aqueous electrolytes on a wider range electrode surfaces.

Figure 1
Spark Plasma Sintering Study on the Super Ionic Glass Ceramic Conductor: Li7P3S11
Authors: Nguyen Han , Hy Sunny , Chu Iek-Heng , Ong Shyue Ping , Meng Ying Shirley 
Published: February 2020

Solid-state electrolytes that can perform on par with conventional liquid electrolytes are highly sought after for use in all solid-state batteries. An all solid-state battery promises to operate without the possibility of catastrophic failure and have substantially longer self-life than conventional batteries. The Li7P3S11 glass-ceramic is one class of solid electrolytes that could meet the sought after power and reliable performances. We demonstrate a rapid synthesis and densification of the supersonic conductor electrolyte Li7P3S11via spark plasma sintering (SPS) technique. Dense solid-state electrolytes have been formed with a room temperature ionic conductivity is comparable to conventional liquid electrolyte.

Hayashi, A., Ishikawa, Y., Hama, S., Minami, T. & Tatsumisago, M. Fast Lithium-Ion Conducting Glass-Ceramics in the System Li[sub 2]S-SiS[sub 2]-P[sub 2]S[sub 5]. Electrochem. Solid-State Lett.
6, A47 (2003).

Seino, Y., Ota, T. & Takada, K. A sulphide lithium super ion conductor is superior to liquid ion conductors for use in rechargeable batteries. Energy …
7, 627 (2014).

Hayashi, A., Minami, K., Mizuno, F. & Tatsumisago, M. Formation of Li+ superionic crystals from the Li 2S-P2S5 melt-quenched glasses. J. Mater. Sci.
43, 1885–1889 (2008).

Minami, K., Hayashi, A. & Tatsumisago, M. Crystallization Process for Superionic Li7P3S11 Glass-Ceramic Electrolytes. J. Am. Ceram. Soc.
94, 1779–1783 (2011).

Minami, K., Hayashi, A. & Tatsumisago, M. Crystallization Process for Superionic Li7P3S11 Glass-Ceramic Electrolytes. J. Am. Ceram. Soc.
94, 1779–1783 (2011).

Eom, M., Kim, J., Noh, S. & Shin, D. Crystallization kinetics of Li2S–P2S5 solid electrolyte and its effect on electrochemical performance. J. Power Sources
284, 44–48 (2015).

Acknowledgments
This work was supported by the National Science Foundation under grant number ACI-1053575.
Improvement of Cycling Performance of Silicon-Graphite Composite Anode Using Blended Electrolyte Additives
Authors: Jo Hyuntak , Tran Xuan Minh , Nguyen Dan Thien , Jeon Do-Man , Yang A-Reum , Song Seung-Wan 
Published: February 2020

Silicon-graphite composite anode materials are potential alternatives to graphite anode material for high-energy density Li-ion batteries, as the theoretical specific capacity of silicon is ten-fold larger than that of commercialized graphite.1,2 However, the major drawback of silicon-based anode material is a short cycle life caused by large volume change, low electrical conductivity and mechanical disintegration of particles. To overcome those issues, a variety of methods for improving cycle performance of silicon-based anodes have been researched, such as the use of composite with larger fraction of graphite,3,4 modification of surface property of silicon,4 and the use of new binder, nanostructured silicon, and functional electrolyte additives.3 Recently, the batteries with composite material containing very low fraction of silicon are being commercialized, which can accommodate the large volume change of silicon and obtain reasonable electrical conductivity. Another promising approach is the control of electrode-electrolyte interfacial reaction for the formation of a stable solid electrolyte interphase (SEI) utilizing functional electrolyte additives, which has to be based on a basic understanding of interfacial phenomena. In this presentation, we report the improved cycle performance and the interfacial phenomena of silicon-graphite composite anodes under the condition of various blended additives.

Acknowledgements

This research was supported by the Korean Ministry of Trade, Industry & Energy (10049609), National Research Foundation (2012026203), and Nano-Material Technology Development Program by the Ministry of Science, ICT and Future Planning (2009-0082580).

References

1. B. A. Boukamp, G. C. Lesh and R. A. Huggins, J. Electrochem. Soc., 128, 725 (1981).
2. R. A. Sharma and R. N. Seefurth, J. Electrochem.
Soc., 123, 1763 (1976).
3. S. Hong, M.-H. Choo, Y. H. Kwon, J. Y. Kim and S.-W. Song, J. Electrochem.
Soc., 161, A1851 (2014).
4. J.-S. Kim, C. C. Nguyen, H.-J. Kim and S.-W. Song, RSC Adv.,
4, 12878 (2014).
Structrual Stabilization of Layered NaxMO2
Authors: Matsui Masaki , Mizukoshi Fumikazu , Imanishi Nobuyuki 
Published: February 2020

In recent years, Na-ion batteries are expected as a potential post Li-ion battery system because of the abundant resources. A lot of layered materials: NaxMO2 (M=Cr, Mn, Fe, Co, Ni) has been investigated as candidate positive electrode materials for Na-ion batteries. Substitution of the transition metal in NaxMO2 is common strategy for the improvement of their cycling performances. On the other hand, an elemental substitution of Na sites has never been investigated because the substituted atoms easily hinder the smooth diffusion of Na+ in the active materials. In the present study, we intentionally substituted the Na+ sites in the P2-type NaxCoO2 with Ca2+ and investigated how it affected to the electrochemical properties.
The XRD study showed that the calcium substitution suppressed the lattice mismatch of the co-existing two phases with some shrinkage of the lattice constant along c-axis. The several voltage steps observed at the peculiar compositions of the NaxCoO2 were eliminated by the calcium substitution. We suspect the calcium should have hindered the sodium ions and the vacancies to take the ordered form. As a consequence the most of the biphasic regions in the voltage profile were disappeared. The suppression of the phase transformation during the charging-discharging process improved the cycling performance of the NaxCoO2 especially at high charging-discharging rate as shown in Fig.1. The XRD patterns after the cycling test showed that the NaxCoO2 formed a sodium poor phase, while the substituted calcium ion mostly suppressed the phase separation. The results showed that the cycleability of the layered NaxMO2 could be improved not only by the materials design of MO2 slab, but the sodium ion layer ordering.

Figure 1