bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fe2O3/Carbon Nanocomposite As Cathode Catalyst for Non-Aqueous Lithium-Air Batteries
Authors: Wu Maochun , Zhao Tianshou 
Published: February 2020

Thanks to the highest capacity of lithium metal (3.86 × 103 mA h g-1) and inexhaustible oxygen in the atmosphere, lithium-air battery offers the promise of a remarkably high theoretical specific energy density up to ~11 kW h g-1, which is comparable to that of conventional fuels [1]. However, the development of lithium-air batteries is hindered by the high overpotential, low rate capacity, and poor cycling performance. The cathode has been shown to be the bottle-neck of rechargeable lithium-air batteries, wherein the sluggish oxygen reduction/evolution reaction (ORR/OER, especially OER) kinetics not only results in a large overpotential, but also causes the poor rechargeability. Thus, it is of great significance and urgency to enhance the electrochemical performances of the cathode. One effective way is to design high efficient catalysts to reduce the charge overpotential. Despite the precious Ru based catalysts have shown promising results as a catalyst for lithium-air batteries, its scarcity and high price will restrict the wide application. As a result, other non-noble transition metal/metal oxides (e.g., MnOx, CoOx) with activities for ORR and/or OER have drawn great interests for lithium-air batteries [2, 3]. Oxides of iron, which in the same group of Ru in the periodic table, however, is less investigated.
Herein, we proposed a facile method to fabricate Fe2O3/carbon nanocomposite cathode materials in which Fe2O3 nanoparticles with a diameter of 4-6 nm are deposited onto the carbon surface, as shown in Figure 1. The electro-catalytic activities were investigated by linear sweeping voltammetry (LSV) and discharge-charge profiles. The results show a lower onset potential and a larger OER current density, suggesting that Fe2O3 is an effective OER catalyst. Moreover, a non-aqueous lithium-oxygen battery with this cathode demonstrates a remarkably 430 mV lower charge overpotential and a dramatically improved cycling life.
More detailed experimental results will be presented in the meeting. And some possible mechanisms of the catalytic effect will also be discussed.

Figure 1
Performance of Li-Air Battery Cell with Folded Structure
Authors: Park Jung Ock , Kim Joon-Hee , Choi Kyoung Hwan , Lee Heung Chan , Im Dongmin 
Published: February 2020

The Li-Air batteries which convert the electrochemical reactions of lithium and O2 into electrical energy have high theoretical gravimetric capacity (3861 mAh/gLi) that is ten times higher than that of lithium ion batteries (372 mAh/gc). Its potential to generate high energy density makes it a promising candidate to replace the lithium ion batteries which practically reached the gravimetric energy density limit in the electric vehicle applications. To meet the requirements of the electric vehicle applications, the Li-Air batteries need to overcome the technical barriers that limit the cycle life such as electrolyte and cathode instability. Although recent developments have been focused on improving the cycle life (1) and safety (2) of Li-Air battery in efforts to extend its application into the electric vehicle, it is also important to design a cell structure that can achieve the highest possible energy density. The Li-Air battery uses lithium metal, porous carbon layer, protective layer and gas diffusion layer (GDL). The properties of lithium metal anode and porous carbon cathode layer are well known, and the cell design will mainly be affected by the mechanical property of the electrolyte, protective layer and GDL.
Figure 1 shows the schematic of a Li-Air fold cell where the Li metal anode, protective layer, and cathode are folded. The oxygen can be distributed to the cathode through the GDL which is inserted between the two cathode layers that are formed from folding. The cell design enables the two layers of the cathode to share one common GDL layer and thus increasing energy density of the cell. The capacity of the Li-Air fold cell can be controlled by changing the length (L) and the number of folds of the cell. The width (W) of the cell affects the O2 distribution in cathode, thus the choice of W is limited. Figure 2 shows the areal capacity of three Li-Air fold cells which contained polyethylene oxide with LiTFSI as electrolyte in the cathode and protective layer. The cells were tested in 1 atm O2 at 60 C. The capacities of the cells were adjusted by changing the number of folds. For the cells in Figure 2, the three cells had WxL dimension of 1x5 cm and were folded 1, 10 and 50 times which resulted in the cells with capacity values of 0.02, 0.2 and 1 Ah, respectively. Figure 2 indicates that the performance of the Li-Air fold cell is reproducible as the number of folds increase. In the presentation, the effects of cell dimension on cell performance, the technical difficulties of manufacturing Li-Air cells with high energy density as well as the issues that need to be overcome to improve the cycle life will be discussed.
References
1. A. J. Smith, , J. C. Burns, , S. Trussler, , J. R. Dahn , J. Electrochem. Soc. 157, A196−A202 (2010).
2. S. Menkin, D. Golodnitsky, E. Peled , Electrochem. Commun. 11, 1789−1791 (2009).

Figure 1
Analysis of the Active Material Microstructure Constituting the Positive Electrode in Lithium-Ion Batteries Application
Authors: Cabelguen Pierre-Etienne , Peralta David , Cugnet Mikaël , Badot Jean-Claude , Dubrunfaut Olivier , Mailley Pascal 
Published: February 2020

Our project aims to complete an experimental study supported by computer modeling to bring a better understanding of the impact of the microstructure on electrochemical behavior. Research has shown in particular that the material microstructure is of tremendous importance to fully exploit its electrochemical capabilities. Indeed, a same chemical and crystallographic phase can exhibit vastly different energy densities, power capabilities and capacity retention depending on its microstructure.
LiNi1/3Mn1/3Co1/3O2materials (NMC) consisting of different microstructure are used as a model compounds. NMC synthesis is set up via co-precipitation route which allows the adjustment of different synthesis parameters such as the pH, concentrations of reactants and feeding and stirring rates, to obtain different morphologies. It gives the possibility to tune the primary particle crystallinity and morphology from thin nanosized pellets to large micrometric cuboids. The differences in the resulting electrochemical performances are discussed regarding the diffusion of lithium in both solid and liquid phases, the wettability and the electronic conductivity of the material by
By coupling electroanalytical techniques, microscopy and computer simulations, we show that the microstructure induces a fundamental difference in the rate-limiting step of the electrochemical process. The microstructure is first qualitatively and quantitatively investigated using mercury porosimetry, helium pycnometry helium pycnometry and FIB-SEM reconstruction. Cyclic voltammetry shows that porous materials behaviour is indeed limited by charge-transfer over a wide range of scan rates whereas dense materials are rapidly limited by solid-state diffusion. The support of modelling allows us to quantify important kinetics parameters such as diffusion coefficients, diffusion length and exchange surface areas and currents. The electronic conductivity investigated using broadband dielectric spectroscopy. This technique allows to separate and treat individually the different relaxations arising from the different length scales: crystallite, nanostructure, and microstructure. It is shown that the electronic conductivity is highly dependent on the microstructure of the primary particles. Flake-shape particles exhibit a higher conductivity, which has an effect at all larger scales. This study shows that the application of electroanalytical techniques must take into account carefully the microstructure of the studied materials and need the support of modelling to fully understand the electrochemical process.

Figure 1
(Invited) Pixel-Parallel CMOS Image Sensors with 16-Bit A/D Converters Developed by 3-D Integration of SOI Layers with Au/SiO2 Hybrid Bonding
Authors: Goto Masahide , Hagiwara Kei , Honda Yuki , Nanba Masakazu , Iguchi Yoshinori , Saraya Takuya , Kobayashi Masaharu , Higurashi Eiji , Toshiyoshi Hiroshi , Hiramoto Toshiro 
Published: February 2020

To meet the increasing demands for higher performance of video imaging, several 3D integrated CMOS image sensors have been recently studied by using through-silicon vias (TSVs) and micro-bumps [1-2]. Although these sensors improved some of their performances by 3D integration, in-pixel interconnection was not realized because the TSV or bump size was larger than the imaging pixel size.
We have studied on the pixel-parallel 3D integrated CMOS image sensors by using embedded Au electrodes [3-5] suitable for high density integration instead of TSVs or bumps. Fig. 1(a) shows a schematic of the developed CMOS image sensor. Pixels including 128 × 96 photodiodes (PDs) and A/D convertors (ADCs) in the upper layer were connected to 16-bit counters in the lower layer for each pixel. The two functional layers were formed on silicon-on-insulator (SOI) wafers and directly bonded, mediated by Au electrodes embedded in the intermediate SiO2 layer by electroplating and chemical mechanical polishing (CMP). Each pixel size was 80 μm square with a Au electrode of 10 μm in diameter. No voids were observed at the bonded interface.
By measuring the input–output response of the developed sensor, we obtained a linear output to the light illumination intensity. The sensor also had a wide dynamic range of 96 dB, which corresponds to the 16-bit output. Signals were detected even under low illumination of 0.1 lx. Fig. 1(b) demonstrates an example of video images captured by the developed sensor. The 16-bit digital output contrast was adjusted to the standard display by compressed to 8-bit data. We confirmed the pixel-parallel operation without any pixel defects.
In summary, a 128 × 96 pixel-parallel 3D integrated CMOS image sensor with 16-bit A/D converters was successfully demonstrated by applying Au/SiO2 hybrid bonding of SOI layers. The developed process is promising for CMOS image sensors of higher performance and More-than-Moore type devices for the next generation electronics.

References

[1] J. Aoki et al., ISSCC, p.482, 2013.
[2] S. Sukegawa et al., ISSCC, p. 484, 2013.
[3] M. Goto et al., ECS trans., 61(6), p.87, 2014.
[4] M. Goto et al., IEDM, 4.2, 2014.
[5] M. Goto et al., IEEE S3S, 7c.3, 2015.

Figure 1
(Invited) Progress in Process Technologies for SiC Power Devices
Authors: Kimoto Tsunenobu 
Published: February 2020

Power semiconductor devices have attracted increasing attention as key components in a variety of power conversion systems. Although the performance of Si power devices has remarkably been improved, silicon carbide (SiC) (and gallium nitride (GaN)) is promising for advanced low-loss and fast power devices, which can substantially outperform Si-based power devices [1-3]. Because of its strong bonding energy and thermal stability, however, special cares must be paid for fabrication process of SiC devices. This paper reviews present status and challenges of device processing technologies in SiC. In particular, ion implantation and MOS technologies are highlighted, because of their uniqueness, importance, and difficulty.
Ion implantation is a key process in fabrication of almost all kinds of SiC devices, due to the extremely small diffusion constants of dopants in SiC. Wide-range doping control of both n- and p-type conductivity can be achieved by ion implantation, but post-implantation annealing at unusually high temperature over 1650 oC is required to achieve nearly perfect electrical activation. Such high-temperature annealing may cause incongruent evaporation of silicon and surface roughening. The surface roughening can be significantly minimized by using a carbon cap. If the as-implanted lattice damage is of near-amorphous level, lattice recovery is very difficult. Therefore, implantation at elevated temperature is often employed, especially when the implant dose is very high. A variety of extended and point defects are generated by ion implantation in SiC and many of these defects survive after the post-implantation annealing. Thus, designing of device structure (implanted regions) and the process control are critical for fabrication of high-performance SiC devices.
SiC power MOSFETs are an ideal power switch owing to the low on-resistance and fast switching. However, the interface properties of SiO2/SiC MOS structures are still far from a satisfactory level, severely affecting the performance and reliability of SiC power MOSFETs. As in the case of Si power MOSFETs, high dielectric property of the gate oxide, high channel mobility, high threshold voltage and its stability are required. Though recent study on MOS structures formed on nonpolar SiC faces (a- and m-faces) has exhibited some promise (reasonably high mobility of 100 cm2/Vs and threshold-voltage stability), basic understanding of SiC MOS physics is still missing. To overcome the limitations of interface characterization techniques, a new method has been developed to accurately characterize the interface states near the band edge, and a clear correlation with channel mobility has been found. Based on these results, several trials to further improve the SiC MOS interface are under investigation.
[1] J.A. Cooper, Jr. and A. Agarwal, Proc. IEEE 90, 956 (2002).
[2] T. Kimoto, Jpn. J. Appl. Phys. 54, 040103 (2015).
[3] T. Kimoto and J.A. Cooper, Fundamentals of Silicon Carbide Technology (John Wiley & Sons, 2014).
(Invited) Intrinsic Reliability Assessment of 650V Rated AlGaN/GaN Based Power Devices: An Industry Perspective
Authors: Moens Peter , Banerjee Abhishek , Constant Aurore , Coppens Peter , Caesar Markus , Li Zilan , Vandeweghe Steven , Declercq Frederick , Padmanabhan Balaji , Jeon Woochul , Guo Jia , Salih Ali , Tack Marnix , Meneghini Matteo , Dalcanale Stefano , Tajilli A , Meneghesso Gaudenzio , Zanoni Enrico , Uren Mike , Chatterjee Indranil , Karboyan Serge , Kuball Martin 
Published: February 2020

GaN devices are promising candidates for the next generation power devices for energy efficient applications. Although astounding performance is already proven by many research papers, the widespread adoption of GaN power devices in the market is still hampered by (1) yield and reproducibility ; (2) cost ; (3) reliability. All three factors are to be considered, but to convince customers to adopt GaN power devices in their next generation products, proven device and product reliability is a must. Cost is kept acceptably low by growing the GaN epi stack on 6inch and 8inch Si substrates, and by processing the GaN power device technology in standard CMOS production lines, with a proper contamination control protocol in place.
This paper will focus on the most important intrinsic reliability mechanisms for GaN power devices. It will cover gate dielectric reliability, Ohmic contact reliability, accelerated drain stress testing (high temperature reverse bias--HTRB) and high voltage device wear-out testing (high voltage off-state stress--HVOS). The need to do reliability investigations based on statistical data on large area power transistors (100+ mm gate width) instead of small test structures will be emphasized. Acceleration models and statistical distribution models (Weibull, lognormal) are discussed. The correlation between the GaN buffer stack vertical leakage and the parametric drift in prime device parameters under accelerated stress will be highlighted.
Furthermore, since the MOCVD epi layers of the GaN-on-Si buffer stack are key to the device performance, a measurement strategy to extract valuable information about the physical properties of the buffer layers (e.g. activation energies of the traps, conduction mechanisms, …) based on simple transmission line structures, is outlined. This information will also be linked to the so-called “dynamic Ron”, a recoverable reduction in on-state current due to the trapping of charges in the buffer stack and/or the interface.
Finally, it will be shown that through proper engineering of the epi buffer stack, device layout and device passivation scheme, dynamic Ron-free power transistors can be obtained.
(Invited) Challenges and Opportunities for GaN on Diamond Devices
Authors: Graham Samuel 
Published: February 2020

The integration of CVD diamond is seen as an important technology for the passive thermal management of high power GaN devices. Diamond films are often attached to GaN devices either through direct growth on the GaN or through a plasma activated attachment process. Regardless of the method used, a thermal resistance between the GaN and diamond will exist at the interface either through the nucleation and growth of low thermal conductivity diamond at the interface or through a large phonon mismatch at the GaN diamond interace for the bonded approach. While recent demonstrations have shown the benefits of using CVD diamond in lowering the temperature of GaN HEMTs, the theoretical benefits of CVD diamond have not been achieved due to the need to control thermal boundary resistance and the elimination of low conductivity diamond near the interace with GaN.
In this work, we will present data on the thermal performance of GaN on Diamond HEMTs fabricated using bonding as well as CVD growth on the GaN. To better understand the thermal response of these devices, the thermal conductivity of the diamond and quality of the diamond measured using Raman spectroscopy and microscopy approaches will be presented. In addition, the thermal boundary resistance between the GaN and diamond will be presented. A link between the thermal conductivity, thermal boundary resistance, and the bonding or growth approach will be used to elucidate their impact on the total thermal resistance of the GaN on Diamond system. Furthermore, the mechanical integrity of the GaN on diamond interface which can lead to a degradation in TBR measured using a transient thermoreflectance method will be shown. Finally, the temperature distribution in GaN on Diamond HEMTs will be measured and correlated to models of the devices employind properties measured in our experiments. Finally, the propspects for GaN on Diamond based on CVD growth and direct bonding approaches will be discussed.
(Invited) New Directions in GaN Photonics Enabled by Electrochemical Processes
Authors: Zhang Cheng , Yuan Ge , Xiong Kanglin , Park Sung Hyun , Han Jung 
Published: February 2020

So far the impact and promise of GaN devices are focused mainly on optoelectronic and microelectronic devices. The blue LEDs and their inventors have been recognized with Nobel prizes, and GaN power transistors are positioned to play a key role in compact energy efficient power electronics.
The exploration of GaN in photonic devices and structures, which seeks to manipulate optical density of states and propagation properties through linear and non-linear optical index engineering, has received much less attention. In this talk we will summarize our effort in making GaN resonators in one, two, and three dimensions. We will review the performance and challenges associated with different fabrication pathways. With the use of a novel electrochemical process, we are able to selectively porosify or electro-polish GaN. The electrochemical process enables unprecedented tuning in the index of refraction, making it possible to create optical confined structures and laser diodes.
The research is supported by US Department of Energy, National Science Foundation, and DARPA.
Investigation on Alumina Passivation for Improved IGZO TFT Performance
Authors: Mudgal Tarun , Edwards Nicholas , Ganesh Prashant , Bharadwaj Anish , Manley Robert G. , Hirschman Karl D 
Published: February 2020

A study on the influence of the back-channel interface on the operation of bottom-gate indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) is presented. TFTs without any passivation material deposited typically exhibit best-case initial results. However a passivation layer is required for device stability and process integration. The surface of IGZO is very sensitive to deposition conditions of passivation materials; in general additional oxygen vacancies are created which renders the IGZO conductive. Annealing in an oxidizing ambient may reverse this effect and result in devices which exhibit appropriate semiconducting properties.
The impact of passivation using alumina deposited via electron beam evaporation and atomic layer deposition (ALD) has been investigated. A decrease in TFT channel mobility is attributed to the IGZO/alumina back-channel interface degradation associated with the alumina passivation process. Low temperature ALD (e.g. T ≤ 150°C) has been explored to minimize this degradation effect. Pre-passivation and post-passivation anneal treatments have also been explored to better understand the mechanisms involved. Improvements in the back-channel interface were shown to depend on the thickness and deposition method of the alumina passivation layer. Temperature-dependent measurements reveal differences in electrical characteristics including bias-stress stability. Modifications in the passivation and annealing procedures and process integration details have resulted in a marked improvement in the performance of passivated devices.
(Invited) Self-Powered, Wireless Medical Sensor and Devices
Authors: Li Zhou 
Published: February 2020

Implantable medical devices and integrated wireless healthcare sensors are attracting extensive attention, but the batteries used for powering these devices usually display a limited lifetime. Although battery technology has improved, sustainable power sources for cardiac pacemakers, neural stimulators and other implantable biomedical devices are required. Mechanical energy was considered as one of most abundant and accessible energy sources around the human body. When a small system can efficiently convert mechanical energy in our daily life, this system would be a suitable solution for electricity generation and significantly extend the lifetime of the electronic devices, especially in medical area.
Recently, triboelectric nanogenerator (TENG) has attracted much attention and been considered as another potential solution for harvesting mechanical energy. With its high output performance, outstanding biocompatibility and low cost, TENG has been studied for powering implantable medical electronic devices. Here, we demonstrated an in vivo biomechanical-energy harvesting using a TENG. An implantable triboelectric nanogenerator (iTENG) in a living animal has been developed to harvest energy from its periodic breathing. We also developing an encapsulation method for protecting iTENG from the contamination or liquid infiltration of the surrounding environment. Another important consideration is the versatility of the energy harvesters, which can facilitate the integration between iTENG and the various implantable medical electronics and promote the development of self-powered implantable medical devices and wearable/portable electronics. We also designed viable inner connections and universal outlet connectors for the system. The power management elements and NG were integrated on a flexible substrate; therefore, the entire system could be a “Plug and Play” mobile power source. The system was also packaged by PDMS as a waterproof implantable full energy unit for implantable medical electronic devices.
The energy generated from breathing and body moving was used to power a prototype pacemaker and a low-level laser cure (SPLC) system, respectively. It was found that the self-powered system could regulate the heart rate of a rat and significantly accelerated the mouse embryonic osteoblasts' proliferation and differentiation. This is a significant progress for fabricating self-powered implanted medical electronic devices using TENG as a power source.

Figure 1