bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Nanoscale Imaging of Exciton Localization in Carbon Nanotubes with Far-Field Microscopy
Authors: Danné Noémie , Godin Antoine G , Kwon Hyejin , Kim Mijin , Lounis Brahim , Wang YuHuang , Cognet Laurent
Published: February 2020

Sub-wavelength localization of single molecule emission allows super-resolution imaging in the far-field, in particular upon control of molecule blinking properties. This possibility opened many applications in biology[1]. Accordingly, by inducing and analyzing nanotube photoluminescence blinking [2], far-field super-resolution imaging of exciton luminescence was demonstrated in pristine carbon nanotubes and in addition, the presence of luminescence defects which were undetectable with regular diffraction-limited far-field microscopy, could be revealed [3].

The chemical control of nanotube brightening through the creation of luminescent defects [4] triggered great interest about exciton localization processes in carbon nanotubes as well as great hopes for many applications ranging from quantum optics to biological applications. We will present our current efforts to study luminescent defect localization in carbon nanotube having controlled chemical and morphological properties [5].

References

[1] Godin et al , Biophys. J, (2014).

[2] Cognet et al, Science (2007).

[3] Cognet et al, Nanolett. (2008).

[4] Piao et al Nat. Chem. (2013).

[5] Danné et al in preparation
Development of Utility Friendly Olivine Based ESS in Esstalion Technologies
Authors: Asakawa Yuichiro , Daigle Jean-Christophe , Yasuda Masayuki , Karim Zaghib , Uesaka Shinichi
Published: February 2020

One of the promising approaches for striking a balance of realizing sustainable society and maximizing utility’s profit is to apply energy storage system (ESS). There’re many use cases proposed (1), such as reserve, regulation, peak shaving, time shift, load following, smoothing, and minimum emission. To answer these demands, the development of a battery with high rate of charging and discharging, a longer cycle life and safe is imperative.

Esstalion Technologies Inc. was established in 2014 as a joint venture company between Sony Corporation and Hydro-Québec.(2)

We are the first corporate joint venture between battery manufacturer and utility.

Since then, we’ve developed utility friendly ESS based on lithium ion battery technology for grid scale utilization.

Since we put our importance on safety and long-life, our core technology is olivine based material which is patented by Hydro Québec and commercialise by Sony as Fortelion. (3)

We’ve started in field testing using 1.2 MWh ESS in 2016.

In Esstalion, we try to bring innovation by gathering “multi-wisdom” in ONE ESSTALION team, doing the new material research, BMS/EMS development and ROI calculation etc.

We propose a brief review of our technologies and we will show an example of our efforts to enhance the key properties of the Li-ion battery.

(1) Pacific Northwest National Laboratory, Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage Systems

(2) Press Release, Establishment of Esstalion Technologies, Inc., a joint venture between Hydro-Québec and Sony, 2014

(3) News Release, Sony Launches High-power, Long-life Lithium Ion Secondary Battery

Using Olivine-type Lithium Iron Phosphate as the Cathode Material, 2009
Meso and Microstructural Interactions in Porous Lithium-Ion Batteries
Authors: Deva Abhas , García R. Edwin
Published: February 2020

Rechargeable batteries are porous electrochemical structures composed of secondary particles, which are aggregates of single crystal primary particles, pores, cracks, and processing-induced phases and features. The underlying meso and microstructural topology, including its size, size distribution, morphology and crystallographic orientation of each of the underlying phases impacts the delivered power and energy density. While it is clear that the component with the lowest efficiency will be the bottleneck to performance of the overall device, the understanding of the fundamentals associated to the different electrochemical and chemomechanical interactions of the underlying phases remains unclear. In this paper we will discuss the meso and microstructural limitations associated to porous cathode electrodes, and will outline strategies to tune the response of primary and secondary particle configurations for high power or energy density applications.
An Experimental Analysis on the Impacts of Current Pulsing with Varying Current Amplitudes on Lithium-Ion Cells
Authors: Rajagopalan Kannan Dhevathi Rajan , Weatherspoon Mark H. , Moss Pedro L.
Published: February 2020

Lithium-ion cells can be charged using different techniques. CCCV (constant current, constant voltage) charging is the standard method that is typically employed for charging the lithium ion batteries/cells. A theoretical analysis of pulse charging using varying current amplitudes with the relaxation periods has shown reduction in the charging time without reaching lithium saturation over the period [1]. It is based on the concept of increasing surface concentration of lithium at initial stages and maintaining the concentration value close to the saturation, resulting in enhanced performance.

The objective of this work is to experimentally analyze the impacts of varying current pulse amplitudes on the lithium ion battery materials. This method comprises constant width charging, a rest period and decrease in applied current as the charging progress. Implementing the pulsed currents of different amplitudes on cathodic (Lithium Iron Phosphate, Lithium Manganese Dioxide) and anodic (Graphite and Li 4Ti5O12) half cells separately will impact the electrode materials in various ways. The results of charging time and effects on the electrode materials are compared with conventional charging method.

Figures 1 and 2 show the constant current and a portion of pulsed current profile that are used in the analysis. In this experiment, pulsed current profile is controlled by varying the duty cycle and relaxation periods between pulses while the current amplitudes are reduced as the charging progress. SEM and equivalent circuit modelling based on EIS data are used in analyzing the impacts of both the charging protocols on the lithium-ion cells.

References:

[1] B. K. Purushothaman and U. Landau, “Rapid Charging of Lithium-Ion Batteries Using Pulsed Currents A Theoretical Analysis,” J. Electrochem. Soc., vol. 153, no. 3, pp. A533–A542, Mar. 2006.

Figure 1
Multi-Physics Modeling of Impact Safety of Lithium-Ion Batteries
Authors: Deng Jie , Zhu Min , Bae Chulheung , Miller Ted J. , L'Eplattenier Pierre
Published: February 2020

As lithium-ion batteries are more and more widely used in electrical vehicles and hybrid electrical vehicles, their safety has become a primary concern due to their high energy densities and wide-range working conditions. Previously, experiments such as crush tests, have attempted to mimic the failure process of batteries under abuse conditions, but they usually only give binary pass/fail results and provide limited details of the root causes of failure. Recently, computational modeling has gained a lot of interest because it provides an efficient tool to capture fundamental mechanisms of battery failure. Nevertheless, most of existing models of battery safety either treat the battery as a homogeneous solid and only consider its mechanical response, or focus on the thermal-electrical coupling without consideration of mechanical influence. Here we present a three-dimensional multi-physics model of battery safety that is able to predict coupled mechanical, thermal, electrical and electrochemical responses of automobile lithium-ion batteries under mechanical abuse. This model resolves each component in unit cells of a large format Li-ion cell and applies one-way coupling between mechanical and other types of responses to accommodate the significant differences in time scales. In particular, the mechanical solver predicts the onset of internal or external short circuit at the initial stage of an impact, and then the coupled thermal and electrical solver captures the evolution of temperature and current distribution after short circuit initiation. The electrochemical response is captured by a spatially distributed equivalent circuit model, where empirical parameters are obtained from experimental data. This model has been applied to capture internal and external short circuits and subsequent thermal and electrical responses in different types of cells and modules. Various element formulations have been evaluated to achieve the computational efficiency that will be required for future pack simulations. Model predictions have been compared with experiment data, demonstrating the model capacity and providing insights into the failure mechanisms of batteries during an impact process.
On Cell Variability and Fade Mechanisms in High Energy Density Lithium Batteries
Authors: Nagpure Shrikant C , Dufek Eric J. , Liaw Bor Yann , Wood Sean M , Dickerson Charles C , Tanim Tanvir
Published: February 2020

Li-ion battery technology is approaching its limits in terms of capacity density and energy density based on current anode and cathode materials, which poses a technical challenge for increasing the range of electric vehicles and minimizing overall battery pack size. An alternative lithium battery technology utilizing a high capacity cathode such as a Ni-rich layered oxide can theoretically deliver an energy density upwards of 500 Wh/kg [1].

Combined with a lithium anode and a suitable liquid electrolyte, one such Nickel–rich layered oxide, LiNi0.6Mn0.2Co0.2O2 (NMC 622), has the theoretical potential to deliver batteries with an energy density of at least 500 Wh/kg [2, 3]. Here we have studied the performance of such high energy density full cells comprised of a Li metal anode, NMC622 cathode, and 1.2 M in LiPF6 (3:7) EC:EMC electrolyte.

In order to better understand and compare the performance of different systems, a deep understanding of cell variability and its impact on fade mechanisms is necessary [4]. Hence, challenges in identifying true fade mechanisms due to cell variability will be discussed The presentation will cover the different fade mechanisms and their gradual progression as observed during cycling of these cells. Differential capacity analysis was applied to identify different fade mechanisms and to quantify degradation modes. The different fade mechanisms are related to variations in cells. Statistical analyses will be presented to characterize and quantify cell variability based on the different fade mechanisms observed.

References:

[1] M. Stanley Whittingham, “Ultimate Limits to Intercalation Reactions for Lithium Batteries,” Chem. Rev, 114, 11414 (2014)

[2] Hyung-Joo Noh, Sungjune Youn, Chong Seung Yoon, and Yang-Kook Sun, “Comparison of the Structural and Electrochemical Properties of Layered Li[NixCoyMnz])2 (x = 1/3, 0.5, 0.6, 0.7, 0.8 and 0.85) Cathode Material for Lithium-ion Batteries,” J Power Sources, 233, 121 (2013)

[3] Arumugam Manthiram, Bohang Song, and Wangda Li, “A Perspective on Nickel-rich Layered Oxide Cathodes for Lithium-ion Batteries,” Energy Storage Materials, 6, 125 (2017)

[4]Matthieu Dubarry, Nicolas Vuillaume, and Bor Yann Liaw, “Origins and Accommodation of Cell Variations in Li-ion Battery Pack Modeling,” Intl J of Energy Res, 34, 216 (2009)
Sonochemical Synthesis of Na0.7MnO2.05 and Na0.44MnO2 Insertion Materials for Na-Ion Batteries and Na-Ion Capacitors
Authors: Shinde Ganesh , Baskar Senthilkumar , Nayak Prem Depon , Barpanda Prabeer
Published: February 2020

Energy storage reign supreme in driving the modern lifestyle. Among various energy storage technologies, Lithium-ion batteries (LIBs) and Lithium-ion capacitors (LICs) have attracted much attention due to their high energy and power density respectively. The constraint in the lithium resource impels us to replace Li with other abundant elements. Sodium seems to be the most attractive element to replace lithium with comparable standard electrode potential (-2.71 V vs SHE) and practically unlimited resources making this technology cost effective. Cathode plays an important role in storage devices (batteries and supercapacitors). Various transition metal oxides and polyanionic compounds can be employed as efficient cathode materials, but oxides are favorable owing to their high energy density and ease of synthesis. Current work explores two manganese-based oxides as cathodes for Na-ion batteries (NIBs) and Na-ion Capacitors (NICs): (i) Na0.7MnO2.05 and (ii) Na0.44MnO2.

Depending on the stoichiometry, sodium manganese oxides mainly have two kinds of structures: (i) layered structure (e.g. Na0.7MnO2.05) or (ii) tunnel structure (e.g. Na0.44MnO2), both having large number of vacancies accommodating constituent Na-ions. Na0.44MnO2 is particularly attractive as cathode in NIB because of its unique 3D crystal structure, which greatly facilitates Na+ mobility whereas Na0.7MnO2.05 is good candidate for cathode in NICs owing to its sloppy discharge profile. Here, ultrasonic sonochemical synthesis has been employed to obtain the target compounds, which restricts the final high-temperature annealing duration within 1-2 h. Herein, we will present (i) single crystalline Na0.7MnO2.05 nanoplates with preferential growth in (100) direction facilitating efficient Na+ (de)insertion leading to capacity over 140 mAh/g (average voltage = 2.4 V) and (ii) orthorhombic Na0.44MnO2 having a reversible capacity of 110 mAh/g (average voltage = 2.3 V). The salient features of sonochemical synthesis, structure, morphology and final electrochemical performance of NaxMnO2 oxides (both as NIB and NIC) will be presented combining experimental work as well as first-principle calculations.
Solid Polymer Electrolytes Based on Ion Conductive Nanofiber Framework for Lithium Ion Battery
Authors: Tanaka Manabu , Watanabe Tsukasa , Inafune Yuta , Kawakami Hiroyoshi
Published: February 2020

Solid polymer electrolyte (SPE) have been expected as high safety and reliable materials compared with conventional organic liquid electrolytes. In order to apply polymer electrolytes to all-solid-state Lithium Ion Battery (LIB), it is essential to improve their lithium ion conductivity and membrane stability. In this study, we focused on polymer nanofibers to overcome these issues on SPEs for LIB applications.

Polymer nanofibers have unique characteristics such as high surface area, good mechanical property, and great material transport property [1]. We have reported fabrication, characterizations, and applications of various functional polymer nanofibers prepared by an electrospinning method [2]. Recently, we developed proton or anion conductive polymer nanofibers and revealed their outstanding ion conductive properties [3]. The nanofiber framework (NfF) composite membranes consisting of the ion conductive nanofibers and polymer electrolyte matrix showed remarkable fuel cell properties due to their improved ion conductivity, gas barrier property, and membrane stability [4].

Here presents our recent work on lithium ion conductive polymer nanofibers and their application to all-solid-state LIBs. The electrospinning method was attempted to fabricate lithium ion conductive NfFs composed of lithium salt and polymers bearing ethylene oxide units in their main or side chains. The lithium ion conductive NfF composite membranes were prepared by filling polymer electrolyte matrices into the voids of the NfFs. Electrochemical, thermal, and mechanical properties of the NfFs and NfF composite membranes were evaluated to demonstrate improved electrolyte characteristics. Fabrication and evaluation of all-solid-state LIBs based on the NfF composite membranes will also be reported.

Acknowledgements

This work is partially supported by JSPS KAKENHI (26410225), and a grant (Platform for Technology and Industry) from Tokyo Metropolitan Government, Japan.

References

[1] (a) Thavasi, V., Singh, G.; Ramakrishna, S. Energy Environ. Sci.
2008, 1, 205-221. (b) Reneker, D. H.; Yarin, A. L. Polymer
2008, 49, 2387-2425.

[2] e.g. (a) Arai, T.; Tanaka, M; Kawakami, H. ACS Appl. Mater. Interfaces
2012, 4, 5453-5457. (b) Sode, K.; Tanaka, M.; Suzuki, Y.; Kawakami, H. Nanoscale
2013, 5, 8235-8241.

[3] (a) Takemori, R.; Ito, G.; Tanaka, M.; Kawakami, H. RSC Advances
2014, 4, 20005-20009. (b) Watanabe, T.; Tanaka, M.; Kawakami, H. Nanoscale 2016, 8, 19614-19619. (c) (Focus Review) Tanaka, M. Polym. J.
2016, 48, 51-58.

[4] (a) Tanaka, M.; Takeda, Y.; Wakiya, T.; Wakamoto, Y.; Harigaya, K.; Ito, T.; Tarao, T.; Kawakami, H. J. Power Sources
2017, 342, 125-134. (b) Tanaka, M.; Makinouchi, T.; Kawakami, H. J. Memb. Sci.
2017, 530, 65-72. (c) Watanabe, T.; Tanaka, M.; Kawakami, H. Polym. Int.
2017 66, 382-387.
Enhanced Electrochemical Performance of Li2Mn0.25Co0.75SiO4/C Cathode Materials for Li-Ion Batteries through Reduced Graphene Oxide Addition
Authors: Yamashita Hiroki , Ogami Takaaki , Kanamura Kiyoshi
Published: February 2020

Lithium transition metal orthosilicates (Li2MSiO4, where M=Fe, Mn, Co, or Ni)1 are promising cathode materials for Li-ion batteries with their high capacity (>300 mAh g−1) and high safety. Particularly, Li2MnSiO4 is expected to have a higher discharge capacity than Li2FeSiO4 and Li2CoSiO4, owing to the extraction of two lithium ions at lower voltage (4.1 and 4.5V) relative to them.1 However, practical energy density of Li2MnSiO4 is much less than the theoretical one due to its lower average discharge voltage (~3 V).2 One strategy to improve discharge voltage of Li2MnSiO4 is to substitute Co into Mn. Because Li2CoSiO4 practically exhibits a well-defined plateau near 4.25 V,3 and this is higher than that of Li2MnSiO4. On the other hand, recently, many researchers have focused their work on reduced graphene oxide (RGO) addition for cathode materials to improve their electrochemical performance.4 In this work, various content of RGO addition for Li2Mn0.25Co0.75SiO4/C (LMCS/RGO/C) were investigated to improve its electrochemical performance. LMCS/RGO/C was synthesized by hydrothermal method followed by carbon coating. In addition, Li2Mn0.25Co0.75SiO4/C (LMCS/C) was also synthesized for comparison. Furthermore, crystallographical and morphological data by x-ray diffraction and transmission electron microscope as well as galvanostatic cycling and rate performance were also collected. Fig. 1 shows the first galvanostatic charge-discharge curves for LMCS/RGO/C and LMCS/C at a current rate of 330 mA g−1 in a voltage range of 1.5–4.5 V at 30 °C. The first discharge capacities of LMCS/RGO/C and LMCS/C were 160 and 143 mAh g−1, respectively, and the corresponding coulombic efficiencies were 78.2 and 71.9 %. This indicates that RGO addition for LMCS/C enhances the electrochemical performance. Detailed data of our investigation will be presented in the meeting.

References:

1. M. E. A. Dompablo, et al., Electrochem. Commun., 2006, 8, 1292–1298.

2. A. Bhaskar, et al., J. Electrochem. Soc., 2012, 159(12), A1954–A1960.

3. C. Lyness, et al., Chem. Commun., 2007, 4890–4892.

4. L.H. Hu, et al., Nature Communications, 2013, 4, 1687.

Figure 1
Preparation of 2% Sulfur Doped Li2FeSiO4/C with High Performance for Lithium Ion Batteries
Authors: Luo Xiaoying , Lin Qingyun , Guan Wenhao , Zhang Cunhao , Cao Wen , Cheng Xuan , Zhang Ying
Published: February 2020

Capability of obtaining high capacity by exchanging more than one lithium ion has made lithium iron silicate (Li2FeSiO4) very attractive to be an ideal cathode material for lithium ion batteries. However, high deintercalation voltage and large deformation of Li2FeSiO4
are expected during the delithiation of the second lithium ion. In this work, the nominal 2% sulfur doped carbon coated Li2FeSiO4 composite was prepared by sol-gel precursor and solid-state reaction method. A well crystallized Pmn21 and P21 mixed phase was formed. The initial discharge capacity of 229.2 mAh/g was obtained at 0.1C and room temperature, which corresponds to 1.38 moles per formula unit. The capacity fluctuated to 185.6 mAh/g after 50 cycles, achieving the capacity retention of 81%.
(Corrosion Division H. H. Uhlig Award Address) Advanced Experimental and Modelling Approaches to Understand and Predict Better Corrosion of Metals
Authors: Terryn Herman
Published: February 2020

In the advanced materials industry, there is a clear trend towards more sustainable concepts, and this is certainly also the case for metals. They take a prominent position in the materials market thanks to their multifunctionality and structural and mechanical properties. However, metals are prone to corrosion, and therefore often organic coatings are applied to extend their lifetime. The search for organic coated metals with higher multifunctionality and extended lifetime goes together with the search for more sustainable material concepts in the context of the REACH regulation.

Nowadays, materials are developed for providing components with a lifetime ranging from 10 to 25 years. The lifetime of a material highly depends on its exposure to the environment inducing ageing processes. In the current state of the art, lifetime and ageing assessment are performed by means of experiments, combining accelerated and field testing. The limitation of the first is that the conditions of the accelerated tests are not representative for the real environmental conditions and that there is no proven relationship between accelerated laboratory tests and field performance data. The limitation of the second is that it takes several years (5 to 10 years).

The only way to realise a substantial decrease in the development time of new materials is to introduce modelling in the design cycle. What is needed to realize a breakthrough in this field is a tool that can predict quantitatively and dynamically the corrosion behaviour of (organic coated ) metals. The long term scientific motivation of our research is to build a knowledge and technology platform to enable the prediction of durability behaviour and the estimation of lifetime of (organic coated) metals under long-term environmental ageing and corrosion conditions. This requires advanced research because corrosion of a (organic coated) metal is the result of an intense interplay between several physical phenomena that need to be characterized in real conditions and modelled. Within VUB and TUDelft research we try to focus on both aspects bringing in new advanced combined electrochemical & in situ surface analysis, advanced finite element electrochemical modelling and more recently quantum chemical modelling. During the lecture an overview will be given on our state of the art in the different domains, emphasizing some success but also bringing bottlenecks when it really comes to predictions of corrosion.

Acknowledgements: all VUB-SURF and TUDELFT-CTE colleagues for the excellent collaborations.
Micro-Electrochemical Method for Investigating Localized Corrosion
Authors: Summers Kodi , Chidambaram Dev
Published: February 2020

With an ever increasing demand for advanced materials, methods for developing and studying these advanced materials has also increased. Diffusion multiples is one method that is poised to change how alloys are developed. However, characterization of these diffusion multiples must also be able to match the idealized high-throughput of this method of alloy development. Traditional corrosion studies utilizing electrochemical methods are conducted over relatively large areas and are inadequate for investigation of the micron-scale diffusion layers formed in diffusion multiples. This study will highlight the development of a micro-electrochemical apparatus and report preliminary results of corrosion studies on diffusion couples, non-traditionally welded materials, and technique verification utilizing a micron-scale examination area.

This work was performed under the auspices of the US Nuclear Regulatory Commission (NRC) under contracts NRC-HQ-84-16-G-0033. Ms. Nancy Hebron-Isreal serves as the grants program officer for the NRC awards.
Selection Device with Cu Doped-Chalcogenide Material for 3D Cross-Point Array Structure of 1selector-1resistor Memory Cells
Authors: Kwon Ki-Hyun , Song Myung-JIn , Kim Dong-Won , Kim Hea-Jee , Jin Soo-Min , Kim Do Jun , Yang Hun-Mo , Park Jea-Gun
Published: February 2020

Resistive random access memories (ReRAMs) have been researched to replace current NAND flash memory due to non-volatile memory characteristics, low power consumption, high operation speed, and minimum 4F2 memory cell size[1]. However, to achieve high density of tera-bit level cells, it is needed to operate ReRAM cells with cross-point array structure which required selection device to limit the sneak current path in high-density ReRAM cells. Therefore, recently bi-directional selection devices with two-terminal structure such as ovonic threshold switching (OTS)[2], p-n-p type (PNP)[3], and mixed ionic electronic conduction (MIEC)[4] have been researched to suppress the sneak current path. In this work, we investigated the electrical features of the selection device with Cu-doped chalcogenide material to attain high non-linearity(>105), high on-state current(Ion
)(>10 MA/cm2) and low off-state current(Ioff
)(<0.01 kA/cm2) because Cu ions moved well by E-field and generated interstitials/vacancies acting as dopants. We fabricated the selection device of the structure of W / Cu-doped chalcogenide material / Pt by varying the pattern size of ranging 34 to 1,921 nm as shown in Fig.1. The device performance of Ion
, Ioff
, threshold voltage(VT
), and non-linearity(Ion @Von/Ioff @1/2Von
) was characterized. The Cu-doped chalcogenide material layer was deposited by RF magnetron co-sputtering on W bottom electrode patterned by photo lithography process. Then, Pt top electrode was deposited by DC magnetron sputtering. The selection device with Cu-doped chalcogenide material demonstrated threshold voltage of ~1.0 V, low Ioff
of < 3.66 mA/cm2, Ion
of > 1.82 A/cm2, and non-linearity of > 500 as shown in Fig.2. Finally, we present how the device performance is affected by varying the film thickness, annealing temperature, device size and stack-layer structure. In addition, the uniformity and the reliability of the selection device such as endurance cycling and retention time were investigated. In particular, the mechanism on operating behavior of the selection device will be presented by analyzing the composition and crystallinity of Cu-doped chalcogenide film by using Auger, energy-dispersive X-ray spectroscopy (EDS), cross sectional transmission electron microscopy (TEM) and X-ray diffraction (XRD).

*This work was financially supported by the Ministry of Trade, Industry & Energy(MOTIE, Korea) under Industrial Technology Innovation Program (10068055), the Brain Korea 21 Plus 2016, Republic of Korea and Hanyang University-Samsung Electronics selector research project.

Reference

[1] Choi, B. J et al., Advanced Materials 23, 3847-3852 (2011).

[2] S. Kim et al., VLSI, T240 (2013)

[3] S. Jo et al., IEDM, 6.7.1 (2014)

[4] G. Burr et al., VLSI, p41 (2012)

Figure 1
(Invited) Relationship between Ferroelectricity and Electrical Breakdown in Hf-Zr-O Thin Films
Authors: Migita Shinji
Published: February 2020

Hafnium oxide ferroelectrics are expected in the applications of high-density memories and ferroelectric-gate FETs integrated on LSI. A distinct feature of hafnium oxide ferroelectric is the large coercive field, as large as 1 MV/cm. It is more than tenfold larger than those of conventional perovskite oxide ferroelectrics. This large coercive field is beneficial to preserve a wide memory window in ultrathin films, e.g. 2 V in 10-nm-thickness film. At the same time, it brings a concern of dielectric breakdown during operation because of the high electric field applied in the film. Thus we studied the relationship between the coercive field and breakdown field in ferroelectric Hf-Zr-O thin films.

Metal-ferroelectric-metal (MFM) capacitors were prepared on heavily doped Si substrates. Metal layers were made of TaN film prepared by sputtering the Ta target in Ar and N2 mixture gas. Hf-Zr-O films were prepared by sputtering the HfO2 and ZrO2 targets simultaneously. The metal composition was controlled by shuttering the targets frequently within 0.5-nm-thick of deposition cycle. Following to the deposition of bottom TaN (10 nm), Hf-Zr-O, and top TaN (10 nm) films in sequence, the samples were annealed in a vacuum condition between 600 and 800 degrees Celsius. Device fabrication was finished by photolithography and dry etching.

A result of electrical characteristics of an MFM capacitor, made of 10-nm-thick Hf-Zr-O film (Hf:Zr=50:50), is shown in the figure. Polarization-voltage characters (blue curves) are shown with the left axis. Polarization becomes prominent when the voltage swing exceeds +1 and -1 V. The maximum voltage reaches +3 and -3 V in order to obtain a fully saturated behavior. The remnant polarization and the coercive field are calculated to be 21.9 μC/cm2 and 0.97 MV/cm. These values are reasonable with the results in preceding reports. Current-voltage characters (red curves) shown with the right axis were measured using another die on the same wafer. The leakage current increases gradually with the applied voltage, and the breakdown occurs at around 4 V. The breakdown voltage is larger than the maximum voltage for the saturated polarization, but it is not large enough for the stable operation. In the application of this ferroelectric oxide, we must pay attention with this balance.

Hafnium oxide ferroelectric films are not single crystal and single phase, but are poly crystals and contain ferroelectric and dielectric phases. Thus leakage current and dielectric breakdown might be strongly correlated with the natures of grain boundaries and low-k grains in the films. These issues were not focused when the high-k films were applied in an amorphous phase. The application of new properties in crystalline films has brought us a new challenge of engineering the microstructures.

This work was supported by JST CREST Grant Number JPMJCR14F2, Japan.

Figure 1
Effect of SiO2 Coating Layer on CCTO Particles on Properties of CCTO/PVDF Composites
Authors: Talebinezhad Hossein , Tong Yang , Lu Xu , Li Liangxi , Cheng Zhongyang
Published: February 2020

The ceramic-polymer composites are attracted many researchers attention to using as energy storage. The purpose to get both high breakdown field and high polarization. It is very important to use the high dielectric material as a filler in the polymer matrix to obtain both properties. In many research, ferroelectric fillers like BaTiO3, PbZrO3, BaSrTiO3 have been widely used due to their high dielectric performance [1]. One of the promising materials in this area is CCTO due to showing dielectric constant up to 105 [2-3] The CCTO performance as an energy storage is limited due to low breakdown field and high energy loss. One of the acceptable ways to address this problem is making a composite with a polymer to enhance breakdown field. The ferroelectric polymer like PVDF exhibits high dielectric constant while keep breakdown field high [4-5].

The effect of the SiO2 coating layer and CCTO concentration mixed with PVDF has been studied. The polymer based composites of PVDF/SiO2/CCTO were made by a spin coating process, in which DMF was used as the solvent. The CCTO powders were coated by SiO2 using sol-gel method. The P-E loop test was conducted to measure the energy storage of different composites. The results show an increase in breakdown field while the P-E loop becomes slimmer by making a composite with SiO2. The polarization increased, due to enhancement in the dielectric constant of the composites because of a good connection between matrix and filler made by the additive. The microstructure was studied by using SEM pictures, which shows a better connection between fillers and matrix. The XRD has been used to illustrate the change in the crystallization. The improvement in both polarization and breakdown field make the composite suitable for energy storage usage.

Fig. 1. P-E loop of polymer composites

Refrences:

1- Ke Yu, Hong Wang, Yongcun Zhou, Yuanyuan Bai, and Yujuan Niu, Enhanced dielectric properties of BaTiO3/poly(vinylidene fluoride) nanocomposites for energy storage applications, J. Appl. Phys. 113, 034105 (2013).

2- Laijun Liu, Yanmin Huang, Yunhua Li, Danping Shi, Shaoying Zheng, Shuangshuang Wu, Liang Fang, Changzheng Hu. Dielectric and non-Ohmic properties of CaCu3Ti4O12 ceramics modified with NiO, SnO2, SiO2, and Al2O3 additives. J Mater Sci (2012) 47:2294–2299

3- Qiaoli Zhang, Tao Li, Zhenping Chen, Renzhong Xue, Yongqiang Wang, The non-ohmic and dielectric behavior evolution of CaCu3Ti4O12 after heat treatments in oxygen-rich atmosphere. Materials Science and Engineering B 177 (2012) 168–172

4- Mojtaba Rahimabady, Shuting Chen, Kui Yao, Francis Eng Hock Tay, and Li Lu, High electric breakdown strength and energy density in vinylidene fluorideoligomer/poly(vinylidene fluoride) blend thin films, Appl. Phys. Lett. 99, 142901 (2011)

5- M. Mohammadi, P. Alizadeh, F.J. Clemens, Effect of SiO2 on sintering and dielectric properties of CaCu3Ti4O12 nanofibers, Journal of Alloys and Compounds 688 (2016) 270e279

Figure 1
(Invited) Ab Initio Study of Carrier Transport in Low-Dimensionality Materials
Authors: Fischetti Massimo V , Vandenberghe William G , Gaddemane Gautam , Chen Shanmeng , Ong Zhun-Yong , Chen Edward , Narayanan Sudarshan , Suarez Negreira Ana , Aboud Shela
Published: February 2020

In the past couple of decades, the theoretical study of two-dimensional (2D) materials that could (hopefully) extend the miniaturization of semiconductor devices beyond the perceived limits of the Si CMOS technology has been affected by two major changes. On the one hand, these new materials are poorly known, so that one must rely almost exclusively on ‘basic’ physics (ab initio or ‘first principles”) to assess their properties. On the other hand, density functional theory (DFT) has reached the mature stage of being predictive, thus compensating for the poor practical and experimental knowledge we have of these materials. Sadly, however, a look at the literature shows that, in many cases, predictions made on carrier-transport properties of 2D materials are wildly inconsistent.

Starting from this consideration, here we will consider various groups of 2D materials: 1. Non-van der Waals (vdW) material, such as phosphorene; 2. ‘Pure’ van der Waals (vdW) planar (sp
2) 2D materials, such as graphene; and 3. Non mirror-symmetric 2D crystals, such as silicene, germanene, and stanene. As an example of the first group, the problem of calculating the low-field carrier mobility in monolayer phosphorene will be reviewed and critically discussed, since values for the mobility reported in the literature span almost three orders of magnitude and clarifications are needed. Therefore, we shall pay attention to the drawbacks and advantages of various ab initio models that can be used to calculate charge-transport properties. Regarding planar vdW materials, we will consider the specific case of graphene (and its nanoribbons) as an example in which the supporting substrate plays the beneficial role of stabilizing the crystal and damping the out-of-plane vibrational modes, but also has the detrimental effect of reducing the carrier mobility via scattering with interface hybrid optical-phonon/plasmon modes. In addition, we shall discuss the strong effect that line-edge roughness has on electron transport in armchair-edge graphene nanoribbons (AGNRs). For non-mirror-symmetric crystals, the strong coupling of electrons with acoustic flexural modes (ZA-phonons) causes major concerns, often ignored. We will discussed this, showing that the problem regarding thermodynamic stability of 2D crystals (the ‘Mermin-Wagner theorem’) can bear strong consequences also on electronic transport.

Pseudopotential-based quantum-transport simulations of 5 nm-long field-effect transistors (FETs) will also be shown, comparing devices based on graphene and phosphorene nanoribbons to Si nanowire-FETs.

Finally, the intriguing properties of 2D topological insulators will be discussed, considering the cases of monolayer tin and bismuth and their potential applications in spintronics and low-power high-performance devices.
(Invited) 3D Dirac Semimetal Cd3As2 Thin Films
Authors: Stemmer Susanne , Schumann Timo , Goyal Manik , Kealhofer David , Shoron Omor
Published: February 2020

Three-dimension (3D) Dirac semimetals are a newly discovered class of topological materials that have attracted significant interest. Their electronic structure exhibits a linear dispersion relation around the Fermi energy, making them a three-dimensional analogue of graphene. Epitaxial heterostructures of these materials open a path for the manipulation of topological electronic states by strain engineering, electron confinement, or electrostatic gating, all of which may enable new electronic devices.

Here, we discuss the growth of epitaxial thin films of Cd3As2, a 3D Dirac semimetal, by molecular beam epitaxy. We report on their structure, magnetotansport properties, and field gating experiments using high-k dielectrics. The films are shown to grow in the low-temperature, vacancy ordered, tetragonal Dirac semimetal phase. Extremely high room temperature mobilities (~20,000 cm2/Vs) are achieved in epitaxial layers on III-V substrates. Unusual transport characteristics are observed, such as a negative longitudinal magnetoresistance, i.e., when the magnetic field is applied parallel to the direction of electric current. We vary the film parameters and study their influence on the magnetotransport to distinguish between ‘classical’ phenomena and effects originating from the unique electronic structure.
(Invited) Room Temperature Aging Effect Improvement for Device Stability and Manufacturability of FinFET Technologies
Authors: He Xiaoli , Triyoso Dina , Uppal Suresh , Fu Bianzhu , Zhang Xing , Yamaguchi Shimpei , Yong Chloe , Liu Bingwu , Joshi Manoj , Samavedam Srikanth
Published: February 2020

In CMOS manufacturing industry, device threshold voltage (Vt) stability is a pre-requisite for volume manufacturing. Device architectural elements, process parameters and room temperature aging (Q-time) are the main source of Vt instability. In FinFET technology with metal/high-K gate, device Vt is controlled through effective work function engineering by optimal metal layer thickness as well as controlled Aluminum (Al) doping/diffusion within the gate stack [1-4]. The device Vtcan also be influenced by its architectural elements and process parameters [5] which should be well controlled during the volume manufacturing. However, room-temperature Q-time effects at several stages of the manufacturing process are practically unavoidable.

This work demonstrates post n-work function (WF) deposition Q-time impact on device Vt instability. Longer Q-time induced Vt shifts that are independent of gate length and number of fins, as seen in Figure 1. The root cause investigations were performed using device characterization followed by elemental analysis of the gate stack (Figure 2). It was found that, the content of oxygen (O2) and Al in the gate stack is well correlated to post n-WF deposition Q-time. The device Vt instability can be explained by oxygen incorporation due to n-WF layer oxidation during the Q-time post n-WF deposition and the corresponding reduction of Al diffusion into the high-K capping layer [2, 6]. In this work, n-WF layer thickness/composition was optimized to enable immunity to a larger Q-time limit for volume manufacturing, as demonstrated in Figure 3 from n-WF layer recipe group A to group C. The reliability impact of the gate stack was also assessed. Device benefits such as Tinv scaling and thereby Ion-Ioffperformance improvement was also demonstrated without compromising the reliability.

Reference

[1] L.P.B. Lima et al, J. Appl. Phys., 115, 074504, 2014

[2] A. Veloso et al, Jpn. J. Appl. Phys.52. 04CA02, 2013

[3] L. Kornblum et al, Appl. Phys. Lett., 100, 062907, 2012

[4] C.L. Hinkle et al, Appl. Phys. Lett.,96, 103502, 2010

[5] M. Togo et al, VLSI tech.
Symp. Dig.pp. 140-141, 2014

[6] A. Veloso et al, VLSI Tech.
Symp. Dig. pp. 34-35, 2011.

Figure 1
(Invited) Electrochemical Deposition of Ag- or Au-Based Alloy Films
Authors: Zangari Giovanni
Published: February 2020

Precious metal-based alloy coatings are of interest for both decorative and technological applications, the latter including electrocatalysis, electrical contacts, and plasmonic devices among others [1,2]. The ternary system Au-Ag-Cu in particular provides a playground to finely tune optical and other functional properties. Synthesis of these alloys by electrodeposition further enhances the ability to tune these properties, since metastable phase configurations can be realized by varying the deposition kinetics.

Au-Cu alloys have been deposited by simple and complexing electrolytes; alloy composition could be predicted based on the alloy enthalpy of mixing and the microstructure could be controlled through electrolyte chemistry. In particular, the relative nobility of the two components could be switched via selective complexation, resulting in distinct atomic configurations.

Ag-Cu alloys were also electrodeposited from a simple and a thiourea complexing electrolyte. Deposition from the non-complexing solution shows a lack of luster; the two metals are reduced independently, resulting in phase separation, with limited or no mutual solubility. The thiourea electrolyte on the other hand is capable to form shiny films. The crystal structure in this case shows a gradual variation of lattice constant, suggesting the formation of a continuous series of solid solutions. Electron microscopy however was unable to distinguish between a solid solution or eutectic formation. Metal complexation and tuning of the deposition rate in this case results in a kinetically induced metastable structure.

Finally, Au or Ag alloys with Ni exhibit in the bulk a miscibility gap; electrodeposited films in contrast form apparent solid solutions that are generated by various kinetic phenomena, including kinetic trapping, spinodal decomposition and growth instabilities [3].

References

[1] A.D. Nilekar, et al. "Bimetallic and ternary alloys for improved oxygen reduction catalysis." Topics in Catalysis 46.3-4 (2007): 276-284.

[2] M.G. Blaber, M.D. Arnold, and M.J. Ford. "A review of the optical properties of alloys and intermetallics for plasmonics." Journal of Physics: Condensed Matter 22.14 (2010): 143201.

[3] D. Liang, et al. "Nanoscale Structuring in Au–Ni Films Grown by Electrochemical Underpotential Co‐deposition." ChemElectroChem 1.4 (2014): 787-792.
Electrodeposition of Cobalt-Ruthenium Alloys from Acidic Bath
Authors: Kutyla Dawid , Kolczyk Karolina , Kowalik Remigiusz , Zabinski Piotr
Published: February 2020

The article presents results of tests on potentiostatic electrodeposition of ruthenium and Co-Ru alloys. The tests applying the method of cyclic voltammetry with the use of gold disk electrode (RDE) allowed to define a potentials range in which it is possible to obtain ruthenium and its alloys with cobalt from acid chloride electrolytes.

The influence of electrodeposition parameters and the electrolyte composition on the composition, morphology and structure of the obtained deposits was determined. Co-Ru alloys underwent XRD tests, an analysis with the XRF method and observations using scanning electron microscopy (SEM). Hydrogen evolution tests have been also performed.

Acknowledgment

The authors would like to thank Polish National Science Centre for the financial support provided by the grants: No UMO-2013/09/B/ST8/00211.
(Invited) Stress in Electrodeposited Ni and Cu: Understanding the Effects of Deposition Conditions and Microstructure
Authors: Chason Eric , Rao Zhaoxia , Engwall Alison
Published: February 2020

Residual stresses are a persistent problem in electrodeposited thin films. Stress can lead to cracking or delamination and limit the performance of protective coatings that are grown by electrodeposition. The deposition conditions can greatly modify the stress, so it would be useful to understand how they effect the stress in order to better predict and control it. Therefore, we have performed systematic experiments to measure the dependence of stress on the growth rate and electrolyte composition in electrodeposited Ni and Cu films. Because the microstructure of the film can change with thickness, we have also characterized the grain size evolution for correlation with the stress. This leads to some surprising behavior. For films that grow with tensile stress (high growth rate), the stress becomes less tensile for larger grain size. For films that grow with compressive stress (low growth rate), the stress becomes less compressive/more tensile for larger grain size. These results are interpreted in terms of a kinetic model that focuses on stress-generating processes occurring at the boundary between adjacent grains as the film grows.
A Novel Electrochemical Method for Analysis of Thin Metal Films and Bilayers for Application in the PCB Industry
Authors: Palin Emma J.R. , Ryder Karl Scott , Hillman A Robert , Smith Emma L. , Ferreira Virginia , Sapstead Rachel , Steinke Nina-Juliane , Barker Robert , Dalgliesh Robert
Published: February 2020

The fabrication and assembly of printed circuit boards (PCBs) involves the layering of metals onto an insulating substrate prior to the addition of electronic components. The interfaces between these metal layers are often subject to metal-metal interdiffusion, formation of brittle intermetallics and corrosion, compromising the integrity of the PCB-component solder joints. We have recently developed environmentally sustainable, non-toxic methodologies for application of metal PCB finishes using Deep Eutectic Solvents (DESs) as a novel solvent medium.1-3

Here we focus on the characterisation of metal-metal interfaces in DES media quantifying interfacial structure, layer thickness and morphology using a range of electrochemical and microscopy techniques, including chronoamperometry, cyclic voltammetry (CV) and novel simultaneous thickness electrochemical potential (STEP) measurements coupled with neutron reflectivity (NR.) We have developed the STEP methodology to ascertain some, if not all, of the same information that NR provides.

Deposition of Ag and Cu layers has been carried out in different configurations onto Au substrates and characteristic STEP traces are presented for each upon galvanostatic stripping. The STEP methodology facilitates the identification and quantification of each metal layer by galvanostatic dissolution, which is comparable with time resolved NR measurements. The characteristic features of the STEP measurements are discussed including the shape and potential of the dissolution trace. The degree of mixing between the layers is qualitatively determined from E vs. t traces, along with the layer composition and thickness for systems in which layers remain discrete.

In summary, we present a new, accessible and inexpensive technique, which probes the thickness, composition and interfacial mixing between layers in PCB metal systems using DES electrolytes and galvanostatic stripping methodologies.

[1] A. D. Ballantyne, G. Forrest, M. Goosey, A. Griguceviciene, J. Juodkazyte, R. Kellner, A. Kosenko, R. Ramanauskas, K. S. Ryder, A. Selskis, R. Tarozaite and E. Veninga, Circuit World, 2012, 38(1), 21-29.

[2] K. S. Ryder, A. D. Ballantyne, D. Price and T. Perrett, The PCB Magazine, February 2012, 22-30.

[3] A. P. Abbott, S. Nandhra, S. Postlethwaite, E. L. Smith, and K. S. Ryder, Phys. Chem. Chem. Phys., 2007, 9, 3735–3743.

Figure 1