bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic Layer Deposition on Fabrics for Flame Resistance
Authors: O'Brien S , Cosgrave L , Lodge V , Povey I. M
Published: February 2020

An atomic layer deposition process for coating a wool-synthetic fabric sample with alumina was developed. Samples were processed at 65 degree C and 0.49 mBar, typically for 1000 cycles resulting in a nominal oxide thickness of 100 nm. Samples were characterized by both internal laboratory and commercial indicative flame resistance tests to test its efficacy. It was shown that untreated samples burnt to completion on removal of the ignition source, but in the case of atomic layer deposition treated samples, the flame on the fabric extinguished rapidly on removal of the ignition source, leaving the sample intact after the test. Thermal gravimetric analysis showed that successful fire resistance treatment was achieved by addition of alumina with less than 1% weight of the fabric. Therefore, it can be concluded that atomic layer deposition growth of oxides offers significant advantages in the area of fire resistance treatment, since in addition to its effectiveness, treated fabrics exhibit a negligible increase in weight, remain flexible, breathable and do not undergo any change in colour or palpable texture.
ZrO2/GRP Nanocomposite Based Sensor for the Electrochemical Investigation of an Anti-HIV Phytoconstituent Andrographolide
Authors: Saxena Sachin , Satsangee Soami Piara
Published: February 2020

ZrO­2/graphene (ZrO­2/GRP) modified glassy carbon electrode was fabricated for the study of electrocatalytic and redox behaviour of anti-HIV phytoconstituent Andrographolide (ADL). The modified electrode reported enhancement in the current values and square wave voltammetry was applied for the study of this herbal drug. Morphological characterization was achieved using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry technique. Electrochemical parameters were evaluated at the modified sensor and limits of detection and quantification for the voltammetric determination of ADL was found to be 151.14 ng/mL and 458 ng/mL respectively. ADL was also studied in the blood plasma using ZrO2/GRP/GCE.
Evaluation of Nanocarbon Material Dispersions
Authors: Okazaki Toshiya
Published: February 2020

Nanocarbon materials such as fullerenes, carbon nanotubes and graphenes have attracted considerable attention due to their inherent superior properties. Indeed, the nanocarbon-based materials have been extensively studied for voltaic cells, electrodes, capacitors, reinforced rubbers and the other applications. Researchers have usually discussed the physical properties of the produced materials based on the intrinsic properties of the nanocarbons themselves. Even through the dispersion of the nanocarbons into solution or matrix is one of the most important issues for fabricating advanced composites, the effective evaluation technique of the dispersion states has so far been limited. In this talk, we will show effective evaluation methods for the nanocarbon dispersions for obtaining desired properties of the composite materials.

 

This paper is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
Non-IPR Chlorofullerenes
Authors: Poblet Josep M. , Alegret Núria , Azmani Khalid , Abella Laura , Rodríguez-Fortea Antonio
Published: February 2020

The rule per excellence governing the stability of fullerene cages is the well-known Isolated Pentagon Rule, or IPR. Fullerenes violating the pentagon rule have been obtained in situ through (i) encapsulation of metallic clusters inside the cavity or by (ii) external addition of halogenated species. The endohedral non-IPR cages (type i) appeared in the 2000, with the simultaneous discovery of Sc2@C66 and Sc3N@C68;[
1
] the halogenated IPR-violating fullerenes (type ii) appeared in 2004 with the characterization of the first empty non-IPR cage C50Cl10.[
2
] From then on, the list of non-IPR cages synthesized with any of the two functionalizations has increased significantly. It is important to note that there exists no IPR-violating isomer obtained both as metallo-endohedral and chlorinated fullerene, suggesting that isomers encapsulating metals are not suitable to be obtained with halogen derivatization. The factors that govern the formation of metalloendohedral fullerenes are well-known.[
3
] Now, we intend to discover which are the elements that favor the formation of chlorinated species. With this goal, we have analyzed several isomers for C66 and other fullerenes that have been observed as chloro- and endofullerenes in order to unravel the features of the non-IPR isomers that make them suitable to be trapped as halogenated fullerenes. 

(1)    Stevenson, S.; Fowler, P. W.; Heine, T.; Duchamp, J. C.; Rice, G.; Glass, T.; Harich, K.; Hajdu, E.; Bible, R.; Dorn, H. C. Nature
2000, 408, 427.

(2)    Xie, S.-Y.; Gao, F.; Lu, X.; Huang, R.-B.; Wang, C.-R.; Zhang, X.; Liu, M.-L.; Deng, S.-L.; Zheng, L.-S. Science
2004, 304, 699.

(3)    a) Rodriguez-Fortea, A.; Alegret, N.; Balch, A. L.; Poblet, J. M. Nature Chem.
2010, 2, 955; b) Campanera, J. M.; Bo, C.; Poblet, J. M. Angew. Chem., Int. Ed.
2005, 44, 7230.

Figure 1
Crystal Structure Analysis of Salts and Derivatives of Cationic Lithium Endohedral Fullerene
Authors: Aoyagi Shinobu , Ueno Hiroshi , Kawakami Hiroki , Nakagawa Koji , Okada Hiroshi , Ikuma Naohiko , Kokubo Ken , Matsuo Yutaka , Oshima Takumi
Published: February 2020

Cationic lithium endohedral fullerene, Li+@C60, has a high tendency to form ion-pair states with anions. The strong intermolecular electrostatic attraction builds unique crystal structures such as the rock-salt structure [1]. The coordinated anions in the crystal affect the position and thermal motion of the encapsulated Li+ cation. The endohedral structure of Li+ cation should be also affected by chemical functionalization. Recently we synthesized a cyclohexadiene adduct of Li+@C60 by the Diels-Alder reaction [2]. The lower LUMO level of Li+@C60 accelerates the reaction late 2,400 times faster than that of empty C60. The salt of Li+@C60(C6H8) with TFPB- (tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) was crystallized by a vapor diffusion method. The single crystal structure analysis was performed by means of the synchrotron-radiation X-ray diffraction. The crystal structure shows that the addition of C6H8 to the C60 cage occurred at the [6,6]-bond to have Cs
symmetry. On the other hand, the encapsulated Li+ cation is localized under a six-membered ring so that the Cs
symmetry of the molecule is broken in the crystal. The peculiar Li+ localization would be a result of an electrostatic interaction with the coordinated TFPB- anions and the addition of C6H8. 

[1] S. Aoyagi et al., Angew. Chem. Int. Ed. 2012, 51, 3377-3381.

[2] H. Ueno et al., J. Am. Chem. Soc.
2014, 136, 11162-11167
Metallofullerenes with Single Carbon Atom in the Endohedral Cluster
Authors: Junghans Katrin , Popov Alexey A.
Published: February 2020

The clusterfullerenes with carbon in the endohedral clusters is the most versatile family in terms of possible cluster compositions 1,2. In addition to its obvious role of forming the fullerene cage, carbon is also found in the core of several types of endohedral clusters, including carbide clusterfullerenes, cyano clusterfullerenes, and more complex cluster. Two types of EMFs with single clusterfullerenes were reported so far, Sc3CH@C80, in which the central carbon atom is bonded by a hydrogen 3, and TiLu2C@C80, in which the μ3-carbido ligand forms a double bond with Ti atom 4. Both types of structures were found as minor components in the synthesis of other EMFs (viz. nitride clusterfullerenes). In this work we report on the advancement in the synthesis of such structure and their detailed characterization. In particular, the crucial role of methane as a reactive gas in the arc-discharge synthesis will be discussed.

(1)          Lu, X.; Akasaka, T.; Nagase, S. Acc. Chem. Res.
2013, 46, 1627.

(2)          Jin, P.; Tang, C.; Chen, Z. Coord. Chem. Rev.
2014, 270-271, 89.

(3)          Krause, M.; Ziegs, F.; Popov, A. A.; Dunsch, L. ChemPhysChem
2007, 8, 537.

(4)          Svitova, A. L.; Ghiassi, K.; Schlesier, C.; Junghans, K.; Zhang, Y.; Olmstead, M.; Balch, A.; Dunsch, L.; Popov, A. A. Nat. Commun.
2014, 5, 3568.
A Novel Organic Electrical Memory Device Based on Metallofullerene-Grafted Polymer
Authors: Cui Rongli , Sun Baoyun , Huang Huan , Guo Xihong
Published: February 2020

Organic memory materials have advantages in flexible, large area film-forming, and low cost compared with inorganic storage materials. Developing new materials with high read-write speed, low-power consumption, multi-value storage capacity and other excellent properties has been a subject for the study of next-generation non-volatile storage devices. Metallofullerenes could be used either as electron acceptor or as electron donor to form charge transfer compound with polymers containing electron withdrawing or electron donor compounds. We successfully used metallofullerene-based polymer to fabricate ITO/Gd@C82-PVK/Al sandwich nonvolatile memory device. The results of I-V test indicated that the new material exhibited typical bistable electrical switching and a nonvolatile rewritable memory effect. The theory calculation indicated that the encaged metal may serve as the important electron trapping center. PVK-Gd@C82 is thus an example of a new type charge-transfer complex that integrates the conventional organic and inorganic charge transfer complexes, which provides a potential method to improve the processing, morphological stability, and electrical performance of organic memory devices.
State-of-Charge Determination in Imbalanced Battery Packs
Authors: Dubarry Matthieu , Devie Arnaud , Cabanel Patrice , Liaw Bor Yann
Published: February 2020

The state-of-charge (SOC) estimation is of extreme importance for the reliability and safety of battery operation in large scale energy storage systems. How to estimate SOC for an assembly of cells in a battery pack remains a subject of great interest.

We recently proposed a viable method for SOC determination and tracking for multi-cell assemblies1. We showed that the battery pack attributes, the relationship between SOC and OCV and the relationship between SOC and capacity, could be accurately derived from the attributes of the single cells within the pack. This allows accommodating cell variability and pack configuration in a new way that does not require intensive computation or complicated calibration and that can be easily implemented in a BMS. This approach only requires two distinct measurements of rest cell voltages of all single cells in the pack at a given state of health. Additionally, two parameters were introduced to characterize and track cell imbalance evolution. From this evolution, the capacity loss can be decomposed into two components, the loss associated to the degradation of the single cells and the loss associated by the evolution of the imbalance. From this decomposition, the evolution of the different contributions could be extrapolated independently in order to reach a more accurate prognosis on the battery pack remaining useful life.

In this work we’ll put this method in application to diagnose and prognose the capacity fading of several battery packs operating under different conditions. We will showcase how the OCV=f(SOC) relationship of the battery pack is connected to the one of the single cells and how it could be calculated via simple voltage measurements. The imbalance evolution will allow be discussed and it will be shown how to quantify the different origins of the capacity loss.

References:

1 “State-of-Charge Determination in Lithium-Ion Battery Packs Based on Two-Point Measurements in Life.” M. Dubarry, C. Truchot, A. Devie and B. Y. Liaw, J. Electrochem. Soc, 162(6), p. A877 (2015). DOI:10.1149/2.0201506jes
Enhanced Electrochemical Properties of Gradient Cathode Material By Coating
Authors: Wu Huiming
Published: February 2020

As lithium-ion batteries vigorously expand into newly emerging application fields such as smart mobile devices, power tools, (hybrid) electric vehicles, and energy storage systems, the demand for high-energy density/high-power density cells is rapidly growing. Among various attempts to meet this stringent requirement, charging cells at a voltage higher than the conventional cut-off at 4.2 V has been suggested as one of the most secured approaches to enhance the energy/power density of cells. Raising the charge cut-off voltage for the cathode material including LiCoO2, LiNi1/3Mn1/3Co1/3O2 (NMC), LiNi0.8Co0.15Al0.05O2 (NCA), LiNi0.5Mn1.5O4, etc, tends to face formidable challenges related to deterioration of cell performance and thermal stability of cathode materials.

One promising approach to resolve these stringent shortcomings of high-voltage cathode materials is the surface modification using inorganic coating materials such as Al2O3 and ZrO2, ZnO, AlF3, Ni3(PO4)2, and AlPO4 on the result products. The process for the material preparation involve calcining the lithium source precursor such as LiOH, Li2CO3, LiNiO2 etc with another precursor such as Co3O4, Co(OH)2, LiNi1/3Mn1/3Co1/3(OH)2, Ni0.8Co0.15Al0.05O2, Ni0.25Mn0.75CO3 etc at high temperature. The coating process happens at results material, which would have a distinctively separation between bulk material with the coating layer. We coat the material on the precursor, and then use the coating precursor to prepare the cathode material.
The Effect of Biofilm Formation in Singapore Seawater on Corrosion of Metal and Alloys: New Observations and Concepts
Authors: Wijesinghe Sudesh Lakshitha , Tan Zixi , Thierry Dominique , Larche Nicolas , Teo Serena , Blackwood Daniel J
Published: February 2020

Biofouling and microbiologically influenced corrosion (MIC) can dramatically reduce the function and lifetime of marine structures. These are mediated by micro-organisms attached to the metal surface and/or embedded in a gelatinous organic matrix (the biofilm). The attachment, development and detachment processes of biofilms lead to an important modification of the metal/solution interface, inducing changes in the type and concentrations of ions, pH, oxygen levels, flow velocity and buffering capacity of the liquid microenvironment or the interface. This feature drastically changes the classical concept of electrochemical interface used in corrosion studies. However, the corrosion characteristics, concepts and mechanisms may depend on the specific conditions; e.g. the influence of particular environment, biofilm characteristics, type of alloy etc.

Stainless steels top the list of the metal and alloys used in marine applications. Ennoblement of stainless steel due to biofilm formation is one of the major problems in sea water applications related to microbiologically influenced corrosion, which may eventually lead for failures. There was lack of data to validate this phenomenon in Singapore and tropical sea water. Therefore, corrosion behavior of marine grade stainless steels and some designs to replicate oil and gas industry has been studied. In situ electrochemical investigations have been conducted and results have been compared to those obtained from Brest, France. For a biological perspective to support corrosion mechanisms, a microbial analysis of biofilm was also performed and results were correlated with corrosion and electrochemical data. Notable differences were observed in Singapore data in contrast to other reported data, and explanation and possible corrosion concepts will be elucidated. Furthermore, crevice corrosion initiation and propagation mechanisms of duplex stainless steels in Singapore sea water were also investigated
The Influence of Water Radiolysis on Corrosion By Supercritical Water
Authors: Hariharan Subramanian , Momeni Mojtaba , Subramanian Veena , Noel James J , Joseph Jiju , Wren Jungsook Clara
Published: February 2020

Development of is attractive because of the high thermal efficiency afforded by operating at supercritical temperatures.  The nuclear core materials to be used in supercritical water reactors (SCWR) will be exposed to the aqueous coolant at supercritical temperatures and under high radiation fields.  Understanding the response of the structural alloys to the aggressive chemical conditions generated by supercritical water radiolysis is important to ensure the integrity and enhance the usable life of SCWRs.  This paper reports on the corrosion behavior of Alloy 625, Incoloy® 800H, and Type-310 stainless steel, the candidate materials proposed for use in a Canadian pressure-tube SCWR heat transport system.  These materials were exposed to simulated reducing and oxidizing conditions in a Hastelloy® autoclave containing subcritical (saturated steam at 285°C) and supercritical water (at 400°C and 250 bar) in the absence of radiation, and while being subjected to gamma radiation at 285°C under saturated conditions, thereby simulating the in situ generation of water radiolysis products.  After exposure, the alloy specimens were retrieved and characterized by SEM-EDX, Raman spectroscopy, XPS, and AES depth profiling.  On all of these materials, the oxide films formed in the presence of radiation were thinner than those on unirradiated surfaces, and those formed in the presence of oxygen were thinner than those grown in the absence of oxygen.  The kinetics of oxide growth were found to be slower at the lower temperature.  The nature of the corrosion products formed and the role of various alloying elements in influencing the protection offered by the corrosion product oxide are discussed in detail.
The Modelling of Pitting Corrosion of Carbon Steel in High Level Nuclear Waste Supercontainer
Authors: Lu Pin , Sharifi-Asl Samin , Kursten Bruno , Macdonald Digby D.
Published: February 2020

Passivity breakdown and pitting on carbon steel, the material for the overpack holding the waste canister inside high-level nuclear waste supercontainer in Belgium, has been studied in simulated concrete pore solution (SCPS) with a pH of 13.5 and the data are interpreted in terms of the Point Defect Model (PDM). The near normal distribution in the critical breakdown potential (V
c) measured in deaerated SCPS with different chloride concentrations is in satisfactory agreement with the quantitative prediction of the PDM. The critical areal concentration of condensed cation vacancies at the metal/ﬁlm interface that leads to passivity breakdown, as predicted by the PDM from the experimental dependence of the V
c on the square root of the voltage sweep rate, ξ < 1.09 × 1016 cm−2, is in excellent agreement with that calculated from the unit cell dimensions of the substrate Fe (ξ ≈ 1.53 × 1016 cm−2) and the barrier layer oxide (Fe2O3) (ξ ≈ 6.89 × 1015 cm−2) for vacancy condensation upon the metal lattice or upon the cation sublattice of the ﬁlm, respectively. This observation provides convincing evidence for the validity of the PDM for modeling passivity breakdown.
Electrochemical Corrosion Behavior of Nanocrystalline Metal Thin Film Prepared By Magnetron Sputtering -- a Recent Work Report
Authors: Liu Li
Published: February 2020

The small grain size and the high volume fraction of grain boundaries result in significantly different corrosion behavior between nanocrystalline materials and corresponding coarse crystalline materials. The results by several electrochemical techniques indicate that in active dissolution, nanocrystallization accelerates the corrosion reactions; in passivation, nanocrystallization increases the passive ability. Further researches indicate that for passive materials such as stainless steel, Al alloys and Ni alloys, nanocrystallization changes the composition of the passive film, which improves the enrichment of passive elements such as Cr. In local corrosion, nanocrystallization increases the unstable points on the surface of the materials, which increases the possibility of local corrosion. However, the excellent ability of element diffusion helps heal the local corrosion point, which inhibits the growth of the local corrosion.

In recently, we use the first principles calculation to study the energy change in the passive film and on the interface. We found that NC thin film promotes the formation of more Cr2O3 to increase the growth rate of passive film: more Cr2O3 increases the formation energy Ef of the passive film. Cr2O3 is apt to form at the interface to make the system most stable, which possesses lowest ER. The diffusion rate of defects and others across the passive film is promoted on NC thin film, which results in the formation of a Cr atom enriched layer at the oxides scale/metal interface. All of those reflect the super passive ability of nanocrystallization structure.

And our group also found a thin membrane passive film over the growing pit on sputtering nanocrystalline stainless steel thin film for the first time, which has two layer structures and possesses higher elastic modulus and hardness. This thin membrane passive film will influence the corrosion behavior of material, especially pitting corrosion.
Functional Optical Devices Based on Highly Ordered Metal Nanostructures Obtained Using Anodic Porous Alumina
Authors: Kondo Toshiaki , Yanagishita Takashi , Masuda Hideki
Published: February 2020

There has been increasing interests in the fabrication process of ordered metal nanostructures due to its applicability to the enhancement of the electric field of the incident light based on the localized surface plasmon resonance (LSPR).  Various functional optical devices based on LSPR have been proposed, such as sensing devices, nonlinear optics, photovoltaic cells, and so on.  The performance of the optical devices is dependent on the shapes and arrangement of metals because the efficiency of the enhancement of the electric field by LSPR is determined by the geometrical structures of metals.  However, the fabrication process of geometrically controlled metal nanostructures with large sample area has not been established so far because of the difficulties in the precise fabrication of nanostructures.  We have reported the fabrication of highly ordered metal nanostructures using anodic porous alumina and its application to the functional optical devices based on LSPR [1,2].  Anodic porous alumina, which is formed by anodization of Al in acidic solutions, is a typical self-ordered mesoporous material.  The ordered metal nanostructures could be obtained using the anodic porous alumina as a template for the fabrication.  One of advantageous points of the process using the anodic porous alumina is the precise controllability of the geometrical structures.  In the report, the fabrication of various types of the metal nanostructures and its application to the substrate for the measurements of surface-enhanced Raman scattering (SERS) will be presented.  The highly ordered metal nanostructures (dots or wires) were fabricated using anodic porous alumina templates.  The obtained structures were applied to the substrates for the SERS measurements.  The SERS activity was optimized by controlling the shape and arrangement of the metal nanostructures.  The present process can be used not only for the fabrication of the SERS substrates but also for the fabrication of functional optical devices requiring the highly ordered metal nanostructures.

[1] T. Kondo, K. Nishio, H. Masuda, Appl. Phys. Express, 6, 102401 (2013).

[2] T. Kondo, H. Masuda, K. Nishio, J. Phys. Chem. C, 117, 2531 (2013).
Metallic Nanoparticles and Nanostructure for Light Trapping
Authors: Tang Yongan , Vlahovic Branislav
Published: February 2020

One major challenge for photovolatics solar cell is to improve its light-to-electrical efficiency while reducing its cost and weight. Thin film solar cells satisfy the demand of the high efficiency, low cost, and low weight. The hydrogenated alloy of amorphous silicon (a-Si:H) has high optical absorption than many other materials, a-Si:H thin film solar cells are able to improve the absorption efficiency, since the minority carrier diffusion length is less than or around 300nm for amorphous silicon. However, there is a limitation in all thin film solar cell technologies, the limitation is that red spectrum absorbance is too low. Excitation of surface plasmons via scattering from noble metal nanostructures was proposed to overcome the limitation, to enhance light-trapping efficiency, and to increase light absorption in red spectrum.  We investigated a sandwich-like solar cell: a-Si:H thin film between a top layer of nano-particles and a bottom layer of metallic structures. We studied the optical absorption efficiency of the a-si:H thin film with nano-metallic particles, and investigate the size and shape of these nano-particles. Our investigations show that for a 100nm thick a-Si:H thin film, deposit an array of nano-metallic cubes or cylinders will increase the optical absorption in the red light (e.g. 650nm) dramatically. We also see the strong light trapping effect of the bottom metallic nano structures as a back reflector.
Fabrication and Characterization of Hybrid Solar Cells Based on Perovskite Materials
Authors: Abdel-Fattah Tarek M , Ebrahim Shaker , Soliman M , Anas M , Moustafa E
Published: February 2020

Perovskite solar cells have gathered great attention in recent years as promising high performance next-generation solar cells with long-term stability at low cost. The aim of this work is to prepare and characterize the perovskite materials, hole transferring materials and electron transferring materials to be used in the fabrication of solar cells. Inverted perovskite solar cells have been fabricated with the following design: fluorine tin oxide (FTO)/electron injection layer/active layer/hole injection layer/metallic upper electrode. MoO3 and CuI as hole injection materials matched the energy levels with FTO. Different electron injection materials have been investigated to improve the collection of electrons generated namely graphene, graphene oxide and ZnO. ZnO nanoparticles was prepared by sol gel method and used as electron injection layer. Aging the ZnO sol for one month yields a better cell performance due to the formation of nanoridges structure. The nanoridges structure enhanced the surface area of the electron injection layer. Different electrodes were deposited on the cell namely Al, Ag and Au.

The  achievable inverted perovskite solar cell efficiency, fill factor, open circuit voltage and short circuit current density were found to be 2.4%, 0.67, 1.0 V and 0.037 mA/cm2, respectively for the following device structure: FTO/ZnO/CH3NH2PbI3/CuI/Au.

 Figure 1. Schematic diagram of the inverted perovskite solar cells

Figure 1
(Invited) Advance of Dye-Sensitized Solar Cells with Organic Dyes
Authors: Murakami Takurou N , Koumura Nagatoshi
Published: February 2020

Dye-sensitized solar cells (DSSCs) have the potential difference between the reduction potential of the dye cation and the redox potential of electrolyte. The cobalt complex redox (Co-redox) electrolyte with the deeper redox potential is one of the candidate to avoid the energy loss for dye regeneration. However, Co-redox electrolyte could induce the fast recombination reaction at the interface between the TiO2 and the electrolyte. The recombination reaction is the reduction reaction of the redox couple with the injected electron in TiO2 and will be the causes of decreasing the open circuit voltage (V
oc). To prevent the recombination reaction, the dyes may play important role as the recombination blocker on the TiO2 surfaces. For the reason, we studied first the effects of steric hindrance of the donor and the π-linker groups in donor-π-linker-acceptors (D-π-As) structured organic dyes on the recombination reaction. The steric hindrance at the donor part in the dye structure reduced the recombination reaction and increased the V
oc of the DSSCs. Conversely, the small steric hindrance at the π-linker groups showed the less recombination reaction because of the higher dye coverage on the TiO2 surface. Furthermore, we studied the effects of the type of donor structure in dye structure on the DSSC performance, and compared the dyes with carbazole (MK-1), coumarin (MK-31), and triphenylamine (MK-88) and N-phenyl-carbazole (MK-90) as the typical donor structure. It found that the triphenylamine can block the recombination reaction due to the steric hindrance of the rotatable phenyl groups.

We also studied the stability of the DSSCs with organic dyes. The binding strength between the dye and the TiO2 surface may affect the heat stability of the DSSCs. Carboxylic acids have generally been used as the anchoring groups for the adsorption of dyes on TiO2 surfaces. However, a phosphonic acid anchor is expected to make more stable bonding to the TiO2 surface because of its tridentate binding capability. In this study, we developed a new carbazole dye that employed a phosphonic acid anchor (MK-94) and studied the effects of the dye anchoring group on the heat stability of DSSCs at 85 °C by comparing MK-94 and MK-2 (a carbazole dye with a carboxylic acid anchoring group). In the initial, the DSSC with MK-94 exhibited a lower short circuit current (J
sc) but a higher Voc than MK-2. After the heat stressing, both dyes showed the decreases in J
sc and V
oc but these were suppressed with MK-94. The drop of the power conversion efficiency (PCE) with MK-94 was kept within 6% after 504 h of heating. The phosphonic acid anchor was effective in extending the long-term heat stability of the DSSCs.
(Invited) Surface Passivation of High-k Dielectric Materials on Diamond Thin Films
Authors: Kovi Kiran Kumar , Majdi Saman , Gabrysch Markus , Suntornwipat Nattakarn , Isberg Jan
Published: February 2020

Single-crystalline CVD diamond films have excellent electrical and material properties with potential applications in high power, high voltage and high frequency applications that are out of reach for conventional semiconductor materials.  For realization of efficient devices (e.g. MOSFET), finding a suitable dielectric is essential to improve the reliability and electrical performance of devices. In the current study, we present results from surface passivation studies by high-k dielectric materials such as aluminum oxide and hafnium oxide deposited by ALD on intrinsic and boron doped diamond substrates. The hole transport properties in the intrinsic diamond films were evaluated and compared to unpassivated films using the lateral time-of-flight technique. 

Also, for the advancement of diamond-based electronic devices, the fabrication of MOSFET is crucial as this device finds applications in numerous fields of power electronics and high frequency systems. The MOS capacitor structure which forms the basic building block of the MOSFET is discussed. Inversion phenomenon crucial for the operation of MOSFET observed for the first time in boron doped diamond will be discussed.
(Invited) Defects and Dopants in Silicon and Germanium Nanowires
Authors: Fanciulli Marco , Belli Matteo , Paleari Stefano , Lamperti Alessio , Molle Alessandro , Sironi Mauro , Pizio Antonio
Published: February 2020

Several architectures for ultra-scaled devices targeting classical and quantum information processing as well as chemical sensing rely on silicon and germanium nanowires (SiNWs, GeNWs). Despite the efforts in the preparation and characterization of these nanostructures some fundamental issues remain relatively unexplored. In particular the investigation of  defects at the interface between the semiconductor and its oxide or other semiconductors or oxides in core-shell structures represent an important challenge, as the NW diameter reduces and the surface-to-volume ratio increases [1,2]. The current experimental data and understanding of the n-type doping of silicon and germanium nanowires produced by different methods will be reviewed. The role of hydrogen and defects at the interface between the semiconductor and its oxide [3-5] in the donor de-activation mechanisms, and the effect of the confinement and dielectric mismatch in determining the donor electronic wave function will be discussed. The implications of the differences between the electronic properties of interfacial defects in silicon and germanium with their respective oxides will be also addressed.

References:

[1]   V. Schmidt, S. Senz, and U. Gösele, Appl. Phys. A. 86, 187 (2007)

[2]   M. T. Björk, H. Schmid, J. Knoch, H. Riel and W. Riess, Nature Nanotech. 4, 103 (2009)

[3]   M. Fanciulli, A. Vellei, C. Canevali et al., Nanosci. Nanotechnol. Lett. 3, 568 (2011)

[4]   M. Fanciulli, A. Molle, S. Baldovino, A. Vellei, Microelectronic Engineering 88, 1482 (2011)

[5] S. Paleari, S. Baldovino, A. Molle, and M. Fanciulli, Phys. Rev. Lett. 110, 206101 (2013)
(Invited) Novel Selector and 3D RRAM Development for High Density Non-Volatile Memory
Authors: Yang Hongxin , Tan Chun Chia , He Wei , Li Minghua , Jiang Yu , Yang Yi
Published: February 2020

The development of a higher density non-volatile memory with the 3D vertical resistive random access memory (VRRAM) has attracted great interest from the industries. However, VRRAM currently faces the challenges in selecting the specific cell due to a large number of leakage paths, and fabrication process difficulties. In order to eliminate the sneak path and reduce the power consumption, we have developed a novel selector based on doped chalcogenide material. This novel selector shows nearly ideal selector performances with >107 on/off ratio, 0.2 V holding voltage, 10 pA off-state leakage current, sharp on-switch slope of 7 mV/dec, <10 ns turn on speed, >109 endurance, >1.6 MA/cm2 on current density. To investigate the VRRAM fabrication process, we have developed a process flow to fabricate VRRAM and demonstrated a single level sidewall TaOx based VRRAM device. These VRRAM devices can work properly and its switching performance is independent on the thickness of the switching material. Beside the novel selector and VRRAM integration investigation, we have also proposed a transistor-based novel VRRAM (TB-RRAM) architecture. By forming the RRAM cells and transistors at different layer simultaneously, the fabrication cost related to the lithography, etch and deposition can be greatly reduced.  Furthermore, with transistor as RRAM selector, better read/write endurance and reliability is expected and it is believed to be industry friendly because of the similar architecture of 3D NAND.
(Invited) Excellent Wetting Behavior of Yttria on 2D Materials
Authors: Addou Rafik , Batzill Matthias , Wallace Robert M
Published: February 2020

A high quality yttrium oxide (yttria, Y2O3) dielectric has been grown on different carbon derivatives materials (carbon nanotubes, exfoliated graphene, chemical vapor deposition graphene).1-5 This opens the possibility to use such dielectric for the fabrication of graphene devices.4-5 In this talk, the good wettability of Y2O3 on graphene is demonstrated using various surface science methods. Furthermore, the favorable wetting behavior of yttria is exploited as an effective seeding layer for atomic layer deposition of Al2O3 on graphene.6 Moreover, we investigated the interface between Y2O3 and the transition metal dichalcogenide MoS2 as well as on highly ordered pyrolytic graphite (HOPG). The growth of the yttria film was monitored in-situ by monochromatic X-ray photoelectron spectroscopy and scanning tunneling microscopy (XPS and STM). Depositing yttrium metal results in a chemical interaction between the adlayer and the substrate. However, no indication of chemical interaction was detected for the Y2O3 growth, formed by evaporating yttrium in background O2 environment. This is due to the initial formation of Y-O bonds, before the weak Y-MoS2 and Y-C interaction occurs. The STM results indicate the formation of a uniform dielectric film on both MoS2 and HOPG surfaces, confirming the previous findings on graphene. In conclusions, our results reveal that the underlying MoS2and graphene remains intact following yttria seed deposition. Photoemission measurements of the graphene/oxide contacts indicate n-type doping of graphene with different doping levels caused by the charge transfer at the interfaces.

This work was supported in part by the Southwest Academy on Nanoelectronics sponsored by the Nanoelectronic Research Initiative.

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[1] R. Addou, A. Dahal, and M. Batzill Growth of a Two-Dimensional Dielectric Monolayer on Quasi-Freestanding Graphene. Nature Nanotechnol. 8, 41-45 (2013).

[2] A. Dahal, H. Coy-Diaz H, R. Addou, J. Lallo, E. Sutter, and M. Batzill Preparation and Characterization of Ni(111)/Graphene/Y2O3(111) Heterostructures. J. Appl. Phys. 113, 194305 (2013).

[3] A. Dahal, R. Addou, H. Coy-Diaz, J. Lallo, and M. Batzill. Charge Doping of Graphene in Metal/Graphene/Dielectric Sandwich Structure Evaluated by C-1s Core Level Photoemission Spectroscopy. APL Mater. 1, 042107 (2013).

[4] H. Xu, Z. Zhang, Z. Wang, S. Wang, X. Liang, and L. M. Peng Quantum capacitance limited vertical scaling of graphene field- effect transistor. ACS Nano 5, 2340–2347 (2011).

[5] H. Xu,  Z. Zhang, H. Xu, Z. Wang, S. Wang, and L. M. Peng Top-gated graphene field-effect transistors with high normalized transconductance and designable Dirac point voltage. ACS Nano 5, 5031–5037 (2011).

[6] A. Dahal, R. Addou, A. Azcatl, H. Coy-Diaz, N. Lu, X. Peng, F. de Dios, J. Kim, M. J. Kim, R. M. Wallace, and M. Batzill. Seeding Atomic Layer Deposition of Alumina on Graphene with Yttria. ACS Appl. Mater. Interfaces 7, 2082-2087 (2015).
(Invited) Non-Covalent Functionalization of Epitaxial Graphene for Atomic Layer Deposition of Dielectric Oxides
Authors: Emery Jonathan D. , Alaboson Justice M.P. , Karmel Hunter J. , Hersam Mark C. , Bedzyk Michael J.
Published: February 2020

The successful integration of graphene with dielectric materials is an important step in the development of high-performance graphene-based nanoelectronics. For optimal performance, dielectric layers on graphene need to be ultrathin, conformal, and the growth process needs to be well-controlled and reproducible. In practice, atomic layer deposition (ALD) – a thin film growth process that utilizes self-limiting surface reactions for digital thin film thickness control – is an industrially relevant route to grow dielectric films and nanostructures for electronic applications. However, the chemical inertness and hydrophobicity of graphene typically cause direct ALD processes to yield films of poor quality (defected, non-uniform, and poorly adhered), thereby limiting the ultimate device performance. The key to successful integration of graphene and ALD film growth resides, therefore, in the ability to tailor the graphene surface in such a way that it is amenable to ALD chemistries, but in a manner that does not perturb the properties of the graphene itself. Here, we utilize non-covalently functionalized monolayers to seed uniform film growth by ALD as well as to facilitate directed growth of dielectric nanostructures, such as nanowire arrays. We specifically highlight the use of synchrotron characterization, including X-ray surface scattering and grazing-incidence small-angle scattering, to assess the influence that the functional layers have on thin film, interfacial, and nanoscale structure.
Impact of Accelerator Decomposition Products to the Stability of TSV Filling Processes
Authors: Rohde Dirk , Haubner Kinga , Jäger Cornelia , Kirbs Andreas , Pölleth Manuel , Gaida Josef , Palm Jens
Published: February 2020

Filling of though silicon vias (TSV) with ECD copper is an important process step to realize high performance 3D integrated microelectronic devices. Organic additives are used to deposit the copper defect free into the high aspect ratio vias. The decomposition of these organic additives can disturb the TSV filling process.

The impact of Accelerator decomposition products to the process stability of a model TSV filling processes was investigated. Copper (I) thiolate was found to be the main contributor to the process fluctuations. Already at very low concentrations the fill performance of a model TSV filling process is disturbed. (Fig. 1)

The chemistry of copper (I) thiolate formation and decomposition is discussed and a method for copper (I) thiolate determination in TSV electrolytes is introduced.

The increase of process stability by counteracting copper (I) thiolate is discussed and illustrated on hand of examples.

Figure 1
Towards Quantification of Contaminants in Electrodeposited Cu Films
Authors: Hai N. T. M. , Grimaudo Valentine , Moreno-García Pavel , Broekmann Peter
Published: February 2020

A Cu electroplating process is typically used in semiconductor industry for the on-chip fabrication of interconnects on non-planar (patterned) wafer surfaces with feature dimensions ranging from the sub-10nm level (advanced Damascene applications) up to the micrometer level (Through Silicon Via technology). The presence of particular additives in the plating bath during the electroplating is a crucial prerequisite for the successful fill of vias and trenches with Cu. The accumulation of contaminants in the resulting Cu film is known to significantly decelerate the post-deposition recrystallization that is mandatory to improve the conductivity of these interconnects. It is therefore vital to develop new analytical techniques allowing a precise (true) quantification of the contamination level in the Cu deposit. Classical Secondary Ion Mass Spectrometry (SIMS) depth profiling approaches only provide semi-quantitative information on the contamination level with a poor depth resolution.

In this contribution we report on a recently developed quantitative depth profiling technique with sub-nanometer depth resolution based on laser ablation ionization mass spectrometry (LIMS). The high vertical depth resolution, a high dynamic range >108 coupled with a high detection sensitivity of ~ 10 ppb allows the identification/quantification of trace amounts of contaminants localized at grain boundaries of the Cu deposit. Results of the LIMS techniques are compared with complementary 3D atom probe tomography experiments.

To demonstrate the capabilities of these analytical techniques we use copper films electrodeposited in the presence of SPS (bis-(sodium-sulfopropyl)-disulfide) and Imep (polymerizates of imidazole and epichlorohydrin) additives as model system. This approach allows the targeted insertion of grain boundaries into the Cu film perpendicular to the growth (depth profiling) direction.
(invited) Copper Electroplating Technology for Packaging
Authors: Lai Chien-Hsun , Yuan Yu Cheng , Arnold Marco , Mayer Dieter
Published: February 2020

Copper pillar is a transformative technology for next generation 2.5D/3D packaging.  Fine-pitch copper pillar bumps have replaced conventional flip chip solder bumps when the need for extremely low profile, high connectivity interconnect is required.  Cu pillar Flip-Chip is expected to grow at a 35% CAGR between 2010 - 2018 in terms of wafer count.  It will be a key interconnect technology in future semiconductor packages.  However, it is not just copper deposition into vias, but also needs high speed trough-mask wafer plating, high uniform bump height, flat bump shape, good surface morphology and electric reliability.  Copper deposition in microvias is effected by electric field which is photoresist shielding causing “current distribution”.  A bump center has higher current density than peripheries, so the shape will become convex.  The inner microvia flow field is another factor which causes higher copper ion concentration at center and forms a domed bump.  Although, these two factors will cause a convex bump shape, additives can influence the electroplating behaviors.  Commercial additives can let bump shape become very flat, but it needs stable flow system and small dosage windows.  CUPUR U is a unique package which can control bump shape by one additive concentration.  It can selectively inhibit the bump center current distribution, let domed bump shape becomes flat, even dimple or dish shape. This property is not only controlling bump shape, but also improve the uniformity.  They can be used in high flow system, high current density (> 20 ASD) and wide dosage windows in copper sulfate system.  The package can be used on other BEOL application, such as micro-bump, RDL, UBM at high speed plating.
Combined Surface-Activated Bonding Technique for Low-Temperature Cu/SiO2 Hybrid Bonding
Authors: He Ran , Fujino Masahisa , Yamauchi Akira , Suga Tadatomo
Published: February 2020

Low-temperature wafer bonding is one of key enabling technologies for manufacturing silicon-on-insulator (SOI), micro-electromechanical systems (MEMS), and the emerging three-dimensional (3D) integration. Among many other bonding approaches, low-temperature SiO2-SiO2 bonding and Cu-Cu bonding have been extensively studied because of their high bonding quality and CMOS compatibility. As an evolution of SiO2-SiO2 bonding and Cu-Cu bonding, Cu/SiO2 hybrid bonding provides both ultrafine metal interconnections and enhanced bonding stability during the single bonding process. However, this bonding approach remains difficult because of the challenging simultaneous surface activation of the hybrid surface. For instance, plasma treatment is effective for SiO2 surface activation, but it may induce formation of Cu2O/CuO and increase of surface roughness on Cu surface, which prevents successful hybrid bonding at low temperatures. Therefore, novel bonding techniques with compatibility with hybrid surface are highly desired for low-temperature Cu/SiO2h hybrid bonding. 

This work develops a combined surface-activated bonding (SAB) technique for low-temperature Cu/SiO2 hybrid bonding at below 200 °C. The technique involves combinations of Ar beam bombardment, Si deposition, and water vapor exposure for prebonding surface activation prior to bonding in vacuum. Homogeneous (i.e., SiO2-SiO2 and Cu-Cu) and heterogeneous (i.e., Cu-SiO2) wafer bonding were carried out with the same bonding technique. Surface properties of the surface-activated wafers have been investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Bonding strength has been measured by crack-opening method and tensile test. Bonding interfaces have been inspected by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Mechanisms of prebonding surface activation and bonding interface evolution during low-temperature postbonding annealing are discussed based on our results.
Understanding the Intrinsic Limits of Ultra-Fast Charge Batteries
Authors: Davies Greg , Hsieh Andrew , Steingart Daniel A
Published: February 2020

The holy-grail of batteries is to achieve a high energy density while being able to rapidly charge and discharge the battery within minutes. This will enable the more widespread adoption of electric vehicles, and design of other rapidly chargeable consumer electronics. It is often believed that charge rate is limited by an intrinsic material limit, however we demonstrate that the ultimate dominating limit is diffusion related. This is a challenge that can be addressed by careful system engineering.

This presentation looks at a simple model of a battery and breaks the charge/discharge rate limitations into the key components, identifying the key factors to designing a fast-charge battery. Specific design methodologies are proposed, and several real-world chemistries are introduced to demonstrate the challenges in real terms.