bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxide TFT Comparator Suitable for Bio Sensor Platform
Authors: Kang In Hye , Han Ye Lin , Hwang Sang Ho , Baek Yeong Jo , Bae Byung Seong 
Published: February 2020

As the interest in personal health care is increasing, research on Bio-Information Technology (BIT) continues to be as vigorous as ever. Particularly, efforts are being made to develop products using bio-sensors capable of free movement and prompt detection. Therefore, a health care device with SOG (System-on-glass) technology is required due to the advantages of miniaturization, low cost, and simple process. These bio-sensor platforms must be consisting of the fully integrated circuit in order to be in contact with or embedded in the human body.
To display the sensing signal, we need analog-to-digital converter (ADC) circuit and 7-segment decoder which can be integrated using n-type amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) on a substrate. These bio-sensor platforms consist of an integrated circuit that converts the analog signal to a digital signal and the 7-segment decoder to show the signal level.
TFTs are required to realize the SOG which integrates all devices on substrates like a glass and plastic etc. Oxide semiconductor TFTs such as a-IGZO TFTs show better performance than amorphous silicon TFTs. Owing to their transparency and higher mobility compared to the amorphous silicon TFTs, a-IGZO TFTs have been studied widely.
Figure shows 9 comparators for digitizing, 9-to-4bit priority encoder and 7-sement decoder for display. An OP amp-based comparator includes two inputs, one is an analog input (Vin) and the other is a reference voltage (Vref) generated by a serially connected resistor array. The input signals are compared with the reference voltages by the comparators, which output “0” or “1” according to the analog input level. Then the binary outputs of the comparator are converted to the binary format (A3, A2, A1, and A0) by a digital encoder. The 4bit outputs (A3, A2, A1, and A0) of the ADC are the inputs of the 7-segment decoder. Among the four outputs of ADC, ‘A0’ is the least significant bit and ‘A3’ is the most significant bit. The outputs of 7-segment decoder are labelled as a, b, c, d, e, f, and g which correspond to each segment of 7-segment display.
The 4bit binary codes from ADC are converted to input signals (a to g) of a 7-segment display. Those circuits with a-IGZO TFTs can be used in applications such as the fully integrated bio-sensor platform and wearable device which are transparent and flexible.
The most complex one in that platform is OP Amp which is comparator to generate binary code and needs high gain to accomplish good performance. The comparator is a circuit that plays an important role in the ADC, and the operation of the ADC is difficult to expect without the correct operation of the operational amplifier. Thus, we proposed OP Amp type comparator with oxide TFT for bio sensor platform.

Figure 1
Interfacial Reaction between Metal and Oxide
Authors: Lee Sang Min , Hwang Sang Ho , Baek Yeong Jo , Han Ye Lin , Kang In Hye , Bae Byung Seong 
Published: February 2020

Transparent oxide semiconductor thin film transistor (TFT) is being used in display such as OLED (organic light emitting diode) display and LCD (liquid crystal display). The active oxide layer in oxide TFT is transparent, comprising band gap higher than 3.0 eV.
In TFT fabrication metal layer contacts to the active oxide layer and the reaction between active oxide layer and metal degrade TFT characteristics due to thin metal oxide formation. In this paper the reaction between the amorphous indium- gallium -oxide (a-IGZO) and metal was studied. Metal oxide formation was reported with interfacial micro-structures between a-IGZO and the metal electrode. TiOx is formed at the interfacial region between Ti and IGZO layers by oxygen out-diffusion from IGZO.
The reaction depends on process parameters such as temperature, annealing time and the environment of annealing. For several metals such as Al, Ti, and Mo, the interfacial reaction by thermal anneal was compared for various annealing conditions. The a-IGZO was deposited on ITO electrode layer and the 0.8 mm diameter metal electrodes are formed on a-IGZO layer. After annealing at various conditions, formation of metal oxide was verified by electrical characteristics. The leakage current and breakdown voltages were measured. Figure 1 shows typical I-V characteristics between metal and ITO electrode.

Figure 1
(Invited) Semiconductor Nanoheterostructures for Photoconversion Applications
Authors: Hsu Yung-Jung 
Published: February 2020

With the inherently high degree of complexity, nanoheterostructures composed of two or more materials joined in unique architectures may exhibit superior synergetic properties that are difficult or impossible to acquire from their individual constituents. For semiconductor nanoheterostructures, the relative band alignment of the constituents promotes effective charge separation to bring them desirable properties for photoconversion applications. Several representative works from our lab including Au-CdS [1,2], Au-ZnS core-shell nanocrystals [3,4], Au-decorated TiO2 nanorods [5], Au-decorated ZnO nanocrystals [6], and Au@Cu7S4-decorated TiO2 nanowires [7] will be introduced to demonstrate the promising potentials of semiconductor nanoheterostructures.

References

[1] Chen, W.-T.; Yang, T.-T.; Hsu, Y.-J. Chem. Mater. 2008, 20, 7204-7206.
[2] Yang, T.-T.; Chen, W.-T.; Hsu, Y.-J.; Wei, K.-H.; Lin, T.-Y.; Lin, T.-W. J. Phys. Chem. C 2010, 114, 11414-11420.
[3] Chen, W.-T.; Hsu, Y.-J. Langmuir 2010, 26, 5918-5925.
[4] Chen, W.-T.; Lin, Y.-K.; Yang, T.-T.; Pu, Y.-C.; Hsu, Y.-J. Chem. Commun. 2013, 49, 8486-8488.
[5] Pu, Y.-C.; Wang, G.; Chang, K.-D.; Ling, Y.; Lin, Y.-K.; Fitzmorris, B. C.; Liu, C.-M.; Lu, X.; Tong, Y.; Zhang, J. Z.; Hsu, Y.-J.; Li, Y. Nano Lett. 2013, 13, 3817-3823.
[6] Chiu, Y.-H.; Chang, K.-D.; Hsu, Y.-J. J. Mater. Chem. A 2018, 6, 4286-4296.
[7] Chiu, Y.-H.; Hsu, Y.-J. Nano Energy 2017, 31, 286-295.
(Invited) Interfacing Graphene with III-Nitrides for Power Device Applications
Authors: Yakimova Rositsa , Kovacs Andras , Kakanakova Anelia , Giannazzo Filippo , Pecz Bela 
Published: February 2020

Full performance of GaN power devices is not attained yet due to their self-heating. Towards solving this issue Silicon Carbide is a common substrate for growth of GaN and AlGaN epitaxial layers. In spite of the superior thermal conductivity of SiC compared to e.g. Sapphire or Silicon, thermal management of GaN based devices is still a challenge.
This talk will review recent research appraising the benefits of graphene integration with III-N for high power electronics. The merits of graphene as a 2D carbon made material are well demonstrated. We will present, from a material perspective, the recent progresses in the growth of high quality GaN layers on graphene templates. The latter are obtained via sublimation epitaxy on SiC and this process and the graphene quality will be also discussed in the view of template design and its role in the subsequent CaN and AlN deposition. Furthermore, the possibility and the advantage of templated growth of novel 2D Nitrides will be discussed, both from experimental and theoretical point of view of their formation mechanism.
In order to gain full understanding of the new structure formation results from HRTEM and STEM characterization will be shown.
Finally, strategies to use graphene for thermal management in high-power AlGaN/GaN transistors will be discussed.
References

A. Kovacs et al. Graphoepitaxy of highquality GaN layers on graphene/6H-SiC, Adv. Mater. Interfaces 2, 1400230 (2015).

F. Giannazzo et al. Phys. Status Solidi A 214, No. 4 (2017)
Multi-Scale Characterization of Lithium Ion Battery Cathodes
Authors: Almar Laura , Joos Jochen , Weiss Michael , Costard Janina , Weber André , Ivers-Tiffée Ellen 
Published: February 2020

Optimizing the performance of the Lithium ion batteries requires further understanding of the relationship between the electrode microstructure and the electrochemical performance. Advanced microscopy methods like focused ion beam-secondary electron microscopy (FIB-SEM) and X-ray tomography have been lately used to characterize the battery electrodes [1,2]. However, the study of the complex morphology of the electrodes is not a trivial task, since relevant details take place at different length scales. One single technique is thus meaningful up to a certain extend but not enough to achieve information of the battery as a whole [3].
By a correlative approach the central issues arising during post-processing the image data can be investigated: (1) segmentation of the carbon (carbon black-binder) domain limited by the lower X-ray tomography resolution, (2) reliability of the small volume fractions of the active material and/or other large features taken by FIB-SEM tomography and (3) impact of inner porosity, fissured texture or agglomerated particles, which demand a high resolution technique, in the transport properties.
In this work, LiNixMnyCo1-x-y (NMC) cathodes are characterized by correlation of both FIB-SEM and X-ray tomography. Relevant microstructural information of each individual phase (i.e. active material, carbon, and pore phases) is determined with their respective volume fraction, surface area, particle size distribution and tortuosity at the different relevant length scales.
In addition, the electrochemical performance of the cathodes is studied by impedance spectroscopy (EIS) combined with distribution of relaxation times (DRT) depicting information about the ohmic resistance (R0), charge transfer (e-) at the interface cathode/current collector (RCC), charge transfer (Li+) at the interface cathode/electrolyte (RCT) and the ionic and electronic transport [4].
As a whole, the possibilities, limits and prospects of both microstructural characterization methods will be critically discussed along with the impact on the results.

References

M. Ender, J. Joos, T. Carraro, E. Ivers-Tiffée, J. Electrochem. Soc.
159 (2012) A972-A980.

P.R. Shearing, L.E. Howard, P.S. Jorgensen, N.P. Brandon, S.J. Harris, Electrochem. Comm., 12 (2010) 374-377.

R. Moroni, M. Börner, L. Zielke, M. Schroeder, S. Nowak, M. Winter, I. Manke, R. Zengerle, S. Thiele, Sci. Rep., 6 (2016) 30109.

J. Illig, J.P. Schmidt, M. Weiss, A. Weber, E. Ivers-Tiffée, Journal of Power Sources, 239 (2012) 670-672.

Figure 1
Development of a Hydrogen Contaminant Detector
Authors: Banas Charles Joseph , Yilmaz Abdurrahman , Aponte Bryan , Bonville Leonard J. , Pasaogullari Ugur , Hesler Gregory , Molter Trent M. 
Published: February 2020

As fuel cell vehicles (FCV) are introduced and commercialized, durability remains a critical characteristic towards competing with the lifecycle of conventional vehicle engines1. Reforming and electrolysis still remain as the dominant production processes for the foreseeable future for the hydrogen fuel. Coupled with transportation, storage, and delivery into FCVs, numerous sources of contamination are possible to introduce impurities into hydrogen fuel, which can enter into and poison the fuel cell, leading to rapid degradation of performance.
In this work, we detail the development of an electrochemical hydrogen contaminant detector (HCD) designed to measure the quality of hydrogen fuel dispensed at the filling station against the specifications outlined by the SAE J27192. Specifically, the role that mass transport plays in the sensor response is discussed. The sensor consists of a two-electrode system, for hydrogen oxidation and evolution in the fueling system environment, which consist of a low surface area platinum and platinum-rhodium alloy couple. A Nafion electrolyte coats the tip of the HCD to conduct protons between the electrodes.
Baseline performance is measured on clean hydrogen, which rapidly degrades when the impurities are presented. Experimental response of the HCD to carbon monoxide is presented3. A thin Nafion film, provides rapid response within 30 seconds, but quickly degraded and delaminated off the electrode surfaces. Development of more durable Nafion electrolyte film is discussed which shows much slower response time due to increased thickness. The effect of relative humidity, alternate electrolytes and high-pressure on the HCD response are also presented.
References
1) U.S. Drive Fuel Cell Tech Team Roadmap, https://www.energy.gov/eere/vehicles/downloads/us-drive-fuel-cell-technical-team-roadmap (2017).
2) SAE International Surface Vehicle Standard J2719TM, http://standards.sae.org/j2719_201511/ (2015).
3) C.J. Banas, L.J. Bonville, U. Pasaogullari and T.M. Molter, ECS Trans., 80(8), 497-507 (2017).
Upscaling the Production of High Temperature Polymer Electrolyte Membrane Fuel Cells – an Assessment of Reproducibility, Performance and Durability
Authors: Bodner Merit , García Héctor R. , Steenberg Thomas , Vassiliev Anton , Alfaro Silvia M. , Avcioglu Gökçe S. , Hjuler Hans Aage 
Published: February 2020

With the globally growing market for renewable energy carriers and converters, the scale of material production is increasing, making it necessary to reevaluate processes and parameters of materials. Even though improvements are without doubt still necessary, fuel cells have a high probability to live up to the requirements of the market regarding power density, lifetime, scalability, costs and system simplicity that have to be met in order to enable a broad commercialization.
Especially high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have clear advantages over other available systems at a comparable technological readiness level. The - in comparison to low temperature polymer electrolyte fuel cells (LT-PEMFCs) - elevated operation temperature increases the tolerance of the platinum electrocatalyst towards gas contamination. This enables a simpler system setup, as extensive gas purification becomes obliterated. Furthermore, the higher temperatures allow a more efficient use of the produced heat, contributing to the overall efficiency [1],[2].
The upscaling of the production of electrodes and membranes for high temperature polymer electrolyte membrane fuel cells, as well as the membrane electrode assembly (MEA) manufacturing post new challenges on product reliability. The choice of production method defines the scalability as well as the product reproducibility.
Different coating processes are feasible for high throughput electrode production, all requiring specific ink properties to ensure sufficient loading and homogeneity. In order to assess the reproducibility and scalability, electrodes based on commercial catalysts are manufactured by spraying, casting and with a slot die process. Electrodes are evaluated in regard to their reproducibility, performance and durability. A new non-destructive method for quality control is introduced. Continuous X-ray scanning of the electrodes allows to determine the Pt loading and distribution over large areas.
Performance and durability are determined during operation with wet reformat, mimicking the gas composition of a methanol reformer. The latest results show degradation rates as low as 1 µV h-1, calculated from after the initial 50 h up to 3000 h at 0.4 A cm-2 (Figure 1). The results and experience are used to assess process requirements and scalability.
[1] Q. Li, D. Aili, H.A. Hjuler, J.O. Jensen (Eds.), High Temperature Polymer Electrolyte Membrane Fuel Cells: Approaches, Status and Perspectives, Springer, Switzerland (2016).
[2] G. Schuller et al., Journal of Power Sources, 347, 47 (2017).

Figure 1
(Invited) Advancement of Thin, Reinforced Membranes for High-Performing, Long-Lasting Proton Exchange Membrane Fuel Cells
Authors: Redmond Erin L. , Maruyama Masashi , Liu Wen K. , Cleghorn Simon 
Published: February 2020

After decades of research and development, commercialization of proton-exchange membrane fuel cell (PEMFC) vehicles is now a reality, and several production scale vehicles have been launched. GORE-SELECT® Membranes (GSMs) enable the Toyota Mirai (2015), Honda Clarity (2016), and Hyundai Nexo (2018)1. However, mass deployment of PEMFC vehicles is hindered by lack of hydrogen infrastructure and higher cost than internal combustion engines2. W. L. Gore and Associates, Inc. (Gore) is committed to supplying the fuel cell market with the highest performance and most durable membranes to support the lowest $/kW system. One approach to simultaneously increase power density and decrease membrane cost (by reducing material content) is to use thinner membranes, ca. 10 µm or less.
Thin membranes facilitate high performance systems by means of higher proton conductance and faster water transport properties, yet durability remains a challenge. Gore is uniquely positioned to deliver high-strength reinforcement layers for the most mechanically durable thin membranes at high volume with superior uniformity. Expertise in engineering fluoropolymer composites has allowed Gore to develop thin membranes that mechanically outlast thicker membranes while exceeding performance, Figure 1. The remaining challenge to address is chemical durability. Higher gas permeance of thin membranes can result in increased radical generation through multiple mechanisms3. As shown in Figure 2, Gore is working to increase the selectivity of protons relative to gas crossover, which is critical for maintaining performance while extending chemical lifetime. Additionally, chemical degradation can be mitigated through advanced additive strategies.
In this talk we discuss Gore’s understanding and advancements of thin membrane technology culminating with the introduction of new state-of-the-art membranes that break the cost / performance trade-off.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the contribution of the Electrochemical Products team of W. L. Gore and Associates, Inc.
REFERENCES

W. L. Gore & Associates, (2018) https://www.gore.com/news-events/press-release/gore-s-fuel-cell-technology-helps-power-latest-hyundai-fuel-cell-vehicle.

D. L. Greene and G. Duleep, Status and Prospects of the Global Automotive Fuel Cell Industry and Plans for Deployment of Fuel Cell Vehicles and Hydrogen Refueling Infrastructure, Oak Ridge, Tennessee, (2013).

M. Zaton, J. Rozière, and D. J. Jones, Sustain. Energy Fuels, 1, 409–438 (2017).

Figure 1
Fabrication of Reinforced Tri-Layer Proton-Exchange Membranes By Dual Fiber Electrospinning
Authors: Powers Devon , Wycisk Ryszard , Pintauro Peter N. 
Published: February 2020

Dual nanofiber electrospinning was used to fabricate a series of tri-layer fuel cell membranes with high proton conductivity and low in-plane water swelling, using 825 EW perfluorosulfonic acid (PFSA) ionomer from 3M Company and poly(amide imide) (PAI) from Solvay S.A. The relative flow rates of the PFSA and PAI solutions, supplied from separate spinnerets (needles) during electrospinning, were adjusted to create three-layer mixed-fiber mats with different PFSA/PAI weight ratios. After electrospinning, the fiber mats were transformed into dense membranes by heating and compaction, where each layer consisted of a PFSA ionomer matrix with an embedded network of reinforcing PAI fibers. The surface layers of all membranes contained 95 wt.% PFSA and 5 wt.% PAI. The center layer, depleted in PFSA, contained either 75 wt.%, 60 wt.%, or 40 wt.% 825 EW PFSA, with a uniform or gradient PFSA/PAI composition. The thickness of the center layer (uniform or gradient composition) was adjusted so that the effective/average composition of the entire membrane was 80 wt.% PFSA and 20 wt.% PAI. The best tri-layer membrane had a total thickness of 17 μm and a PFSA/PAI gradient morphology middle layer. This membrane had a sheet resistance 30% less than a commercial Nafion 211 membrane with a 3-fold decrease in areal water swelling, as compared to Nafion and excellent mechanical properties (a stress at break of 20 MPa versus 22 MPa for neat Nafion 211).
Acknowledgements. The authors thank the US DOE (EERE Cooperative Agreement No. DE-EE0006362) for funding this work and Dr. Michael Yandrasits at 3M Co. for providing the 825 EW PFSA used in this study.
Preparation of Pt3y Nanoparticles Supported on Carbon
Authors: Brandes Benedikt Axel , Cleemann Lars Nilausen , Li Qingfeng , Jensen Jens Oluf 
Published: February 2020

The development of active and stable nanoparticles for the ORR is crucial for the success of hydrogen fuel cells and their application in a new energy environment. Platinum based alloy nanoparticles supported on carbon is still the most widely applied catalyst. Literature suggests that platinum alloys of the rare earth metals, including Pt3Y, imposes a superior activity and stability towards the state of the art catalysts [1].
A number of partly successful attempts to synthesize Pt3Y have been made [2][3][4], but unfortunately, the synthesis routes lead to unacceptable particle sizes and distributions or the formation of undesired PtxY phases next to Pt3Y. In most cases, scaling up is an additional challenge.
Our synthesis approach shows promise to produce phase pure and small Pt3Y nanoparticles with a narrow particle size distribution.
The final sample was acid washed and subsequently studied by XRD, XPS, TGA and TEM. Its ORR performance has been measured using RDE.
The XPS results in figure 1a show that metallic/alloyed yttrium exists on the surfaced of the sample confirming that platinum has indeed alloyed with Yttrium and is stable towards the acid wash. However, some yttrium oxide can also be found. It might be located within the carbon support and protected against acid leaching. The XRD spectrum in Figure 1b suggest that almost pure phase Pt3Y nanoparticles have been formed. Only minor contributions of the patterns originating from Pt and Pt2Y can be observed. Using the Scherrer equation, one finds an average particle diameter of 7 nm. TEM images of the the Pt3Y sample are shown in figure 1c, while figure 1d shows a commercial Pt/C catalyst for comparison. The improvement of activity is not yet as high as anticipated, so further work is needed to understand that and to optimize the manufacturing process. The synthesis process cannot be disclosed in the abstract due to a patenting process, but it will be presented at the conference.
[1] Hernandez-Fernandez, P., Masini, F., McCarthy, D. N., Strebel, C. E., Friebel, D., Deiana, D., … Chorkendorff, I. (2014). Mass-selected nanoparticles of PtxY as model catalysts for oxygen electroreduction. Nature Chemistry, 6(8), 732–738. https://doi.org/10.1038/nchem.2001
[2] Knudsen, B. P. (2016). Synthesis of Platinum Rare Earth Alloy Catalysts for Fuel Cells.
[3] Kanady, J. S., Leidinger, P., Haas, A., Titlbach, S., Schunk, S., Schierle-Arndt, K., … Alivisatos, A. P. (2017). Synthesis of Pt3Y and Other Early-Late Intermetallic Nanoparticles by Way of a Molten Reducing Agent. Journal of the American Chemical Society, 139(16), 5672–5675. https://doi.org/10.1021/jacs.7b01366
[4] Cui, R., Mei, L., Han, G., Chen, J., Zhang, G., Quan, Y., … Han, Z. (2017). Facile synthesis of nanoporous Pt-Y alloy with enhanced electrocatalytic activity and durability. Scientific Reports, 7(December 2016), 1–10. https://doi.org/10.1038/srep41826

Figure 1