bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Epitaxy of Silicon Carbide for Power Devices
Authors: Myronov Maksym 
Published: December 2020

We observe an evolution how electric power is generated, converted, distributed and used. The world making an attempt to move away from fossil fuels towards a more renewable, energy efficient and electrified energy ecosystems, and therefor efficiency in power conversion processes becomes critically important. As the most prominent example, various wide band gap semiconductor materials are entering the power electronics in electric and hybrid vehicles. Among them is a Silicon Carbide (SiC). A major benefit of its characteristics, comparing to Silicon (Si), in terms of switching speed, heat loss and size of power electronic devices, is at least 50 % reduction in energy loss in the form of heat. This saving translates into more efficient power electronics and more energy for an electric motor and therefore for longer mileage with the same battery. Therefore, SiC offers an opportunity to move power electronics beyond the boundaries set by the material limits of Si. From production point of view, SiC is especially attractive because of its compatibility with Si manufacturing technologies.
Modern semiconductor power electronic devices are fabricated out of epitaxial thin films of semiconductors, creating a desired device’s layers stack. Therefore, the epitaxy is absolutely essential for creation of such devices.
SiC is a fascinating material with excellent physical properties. It is a wide band gap semiconductor with high thermal conductivity. It is resistant to chemical etchants and radiation. It has high mechanical strength and biocompatible. SiC is the only Group IV compound semiconductor. And finally one of its polytypes, cubic silicon carbide (3C-SiC), can be grown on Si. There are over 200 polytpes of SiC. All of them are formed from 50% Si and C and consist of hexagonal SiC bilayers. Different stacking sequences of C-Si bilayers produces different crystal structures. Different polytypes have different properties and challenges. Due to this epitaxy is very challenging. Among all known polytypes only 3C-, 4H- and 6H- have been very well researched. Hexagonal polytypes of SiC such as 4H- and 6H-SiC already have commercial applications in power electronics and also used as substrates for gallium nitride (GaN). SiC substrates can be formed from these two polytypes, which can then be used for homoepitaxial growth at high temperatures for device applications. These substrates are extremely expensive, limited to 150 mm diameters and epitaxial growth requires very high temperatures (~1700-1800 °C), which are only achievable in specially designed, hot-walled chemical vapor deposition (CVD) reactors. 3C-SiC is the only polytype of SiC which possesses a zinc-blende crystal structure and can be grown on a Si substrate, below the Si melting point (1410 °C). Epitaxy state of the art and challenges for these polytypes and their application will be reviewed.
Aluminium Electrodeposition in Emimcl-AlCl3 ionogels for Improved Aluminium Batteries
Authors: Leung Oi Man , Ponce de León Carlos , Schoetz Theresa , Prodromakis Themis 
Published: December 2020

Aluminium batteries are promising candidates for the next-generation of energy storage devices, given the natural occurrence of aluminium (third most abundant element) and the intrinsic safety characteristics of the electrolytes used. The specific capacity of an aluminium negative electrode (2980 mAh g-1) is approximately 77% that of lithium (3860 mAh g-1), while its volumetric capacity of 8040 mAh cm-3 far exceeds that of lithium (2060 mAh cm-3), due to its ability to transfer three electrons [1]. Most non-aqueous aluminium batteries utilise electrolytes including inorganic molten salts, deep eutectic solvents, organic solvents and ionic liquids, and operate by the reversible deposition/dissolution of aluminium at the negative electrode and the intercalation of the chloroaluminate ions at the positive electrode.
This work studied the electrodeposition of aluminium from the 1-ethyl-3-methylimidazolium tetrachloroaluminate (EMImCl-AlCl3) ionic liquid and its gel form- the ionogel. Ionogels have previously been shown to improve thermal [2] and moisture stability [3]; here, the ionogel was introduced to widen the potential stability window and enable aluminium deposition from lightweight AlCl4
- anions in Lewis neutral ionogels. Generally, aluminium is deposited by the reduction of heavy Al2Cl7
- ions present only in Lewis acidic ionic liquids, which is typically not possible in neutral and basic compositions as the reduction of the organic cation and subsequent ionic liquid decomposition occurs at a higher potential than the reduction of AlCl4
-.
Lewis acidic and neutral ionogels of varying degrees of gelation were synthesised with polyethylene oxide and EMImCl-AlCl3. The electrochemical behaviour of the electrolytes was investigated by cyclic voltammetry, and aluminium deposits from the Lewis neutral ionogel were confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The deposition of aluminium from a Lewis neutral EMImCl-AlCl3 ionogel [2] was demonstrated for the first time (Fig. 1) [4], serving as a basis for further investigation into the role of polymer additives in developing improved ionogel and semi-solid state electrolytes for aluminium batteries.
[1] G. A. Elia, K. Marquardt, K. Hoeppner, S. Fantini, R. Lin, E. Knipping, W. Peters, J. F. Drillet, S. Passerini and R. Hahn, Adv. Mater., 28, 7564-7579 (2016).
[2] S. A. M. Noor, P. M. Bayley, M. Forsyth and D. R. MacFarlane, Electrochim. Acta, 91, 219-226 (2013).
[3] X. G. Sun, Y. Fang, X. Jiang, K. Yoshii, T. Tsuda and S. Dai, Chem. Commun., 52, 292-295 (2016).
[4] T. Schoetz, O. M. Leung, I. Efimov, C. Zaleski, A. M. Ortega, N. García García, P. Tiemblo Magro and C. Ponce de Leon, J. Electrochem. Soc., 167, 040516 (2020).

Figure 1
Towards Moisture Tolerant Aprotic Lithium-Air Batteries Via Reversibly Cycling LiOH
Authors: Temprano Israel , Liu Tao , Petrucco Enrico , Ellison James , Kim Gunwoo , Jónsson Erlendur , Grey Clare P. 
Published: December 2020

In the light of recent commitments from several European countries to ban the sale of internal combustion engine vehicles in the coming decades, the race to develop electrical storage strategies beyond the capabilities of lithium ion batteries is intensifying considerably. Amongst the many different options, Li-air batteries (LABs) have attracted significant attention due to their comparable energy density to fossil fuels1. Despite of its potential, several fundamental challenges remain to be overcome for their successful development2-4. Amongst these challenges, the instability of the typical discharge products (LiO2 and Li2O2) in the presence of moisture and CO2 represents a fundamental stumbling block5.
The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypassing the inherent limitations caused by the instability of their typical discharge products6. The use of the I-/I3
- redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging to develop due to the multiple reaction paths induced by the oxidation of I- on cell charging7. In this work we demonstrate a reversible LiOH-based Li-O2 battery cycling through a 4 e-/O2 process with low charging overpotential (below 3.5 V vs Li/Li+)8. This is achieved by increasing the oxidizing power of I3
-, which shifts the charging mechanism from IO-/IO3
- formation to O2 evolution.

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I. Temprano, T. Liu, E. A. Petrucco, J. H. J. Ellison, G. Kim, E. Jónsson and C. P. Grey, ChemRxiv, 2020, 12221717.v1.

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Collective Die Bonding: An Enabling Toolkit for Heterogeneous Integration
Authors: Burggraf Jurgen , Uhrmann Thomas , Pires Mariana 
Published: December 2020

The increasing demand for high performance devices with increased functionality onto a single device/package and with reduced form factor were the main factors driving the development of heterogeneous integration technology. Heterogeneous integration (HI) refers to the assembly and packaging of multiple separately manufactured components onto a single chip in order to increase functionality. Components with different functionality, substrate materials and process technologies are joined in a single package in a System in Package (SIP) approach. The functionality of the components could vary throughout the entire device supply chain starting from signal processors to memory, micro-electro-mechanical systems (MEMS) and silicon photonics. The possibility to join multiple functionalities onto a die enables new packaging architectures and design concepts. One such concept is based on the not new concept of die-to-wafer bonding but allows for bonding multiple dies to a wafer in a single process. Such technological approach requires a reliable local multiple-dies bonding technology compliant also to state of the art optical alignment accuracy. Packaging is the final manufacturing process transforming devices into functional products for the end user. Packaging must provide electrical and photonic connections for signal input and output, power input, and voltage control. It also provides for thermal dissipation and the physical protection required for increased product reliability.
In this work we report results using a method and process flow enabling local die bonding compatible with the highest alignment accuracy and cleaning requirements to support a very high yield. A customized temporary carrier with alignment features was utilized to place known good dies (KGD) on the carrier and enable die processing prior to the final bonding process. Such carriers with KGD’s (figure 1) were successfully processed using direct bonding, hybrid bonding, adhesive bonding and metal bonding using as bonding partner different substrate materials like silicon and III-V semiconductor. The process success was verified by the final transfer rate, scanning acoustic microscope imaging and TEM cross section analysis (figure 2). In addition other metrology methods have been identified to monitor the process stability.

Figure 1
(Invited) Insights into the UV-C Optical Absorption of AlN Substrates Grown by PVT
Authors: Dalmau Rafael , Britt Jeffrey , Schlesser Raoul 
Published: December 2020

High temperature growth of AlN single crystals by physical vapor transport (PVT) was used to produce 2-inch diameter AlN substrates free of macrodefects and with average dislocation densities below 103 cm-2 [1, 2]. In spite of its high structural quality and uniformity, AlN grown by PVT has been characterized by high below-bandgap optical absorption in the ultraviolet C (UV-C) region, due to the presence of several deep-level, impurity-related absorption bands. UV-C light emitting diodes (LEDs) operating in the 260-280 nm range are being actively pursued for applications such as water purification and surface disinfection. These devices typically require light extraction through the substrate, for which high transparency in the emission wavelength range of interest is critical to high device performance. Adoption of AlN substrates for use in UV-C LEDs thus requires low optical absorption coefficients in the 260-280 nm emission range. However, several groups have identified an absorption band around 265 nm, which is associated with the carbon impurity, in these substrates [3]. Reducing this unwanted absorption band is critical to enhancing light extraction in UV-C LEDs grown on AlN substrates. In earlier work, co-doping with silicon was shown to reduce the unwanted 265 nm absorption band [4]. Formation of a carbon-silicon defect complex with an absorption band at 225 nm was demonstrated by optical absorption and photoluminescence measurements together with density functional theory calculations [4]. In this work, we have grown large diameter boules with varying concentrations of impurities in order to demonstrate 2-inch AlN substrates with low 265 nm absorption coefficients. The optical properties of double-side polished, c-plane substrates were measured using a high performance UV/Vis spectrophotometer (PerkinElmer Lambda 850). Transmittance and absolute reflectance spectra were collected using a 150 mm integrating sphere, and absorption coefficients were calculated with an approximation-free method [5] which accurately accounted for all reflectance losses. The absorption coefficients at 265 nm were correlated with impurity concentrations measured by secondary ion mass spectrometry (SIMS) of the three most prevalent electrically-active impurities, carbon, oxygen, and silicon, for various locations throughout the boule volume. Growth and characterization results of UV-C transparent 2-inch AlN substrates grown by PVT will be presented.
References
[1] R. Dalmau et al., Mater. Sci. Forum
924, 923 (2018).
[2] R. Dalmau et al., ECS Trans.
92(7), 113-121 (2019).
[3] R. Collazo et al., Appl. Phys. Lett.
100, 191914 (2012); K. Irmscher et al., J. Appl. Phys.
114, 123505 (2013); I. Gamov et al., J. Appl. Phys.
126, 215102 (2019).
[4] B. Gaddy et al., Appl. Phys. Lett.
104, 202106 (2014).
[5] D. C. Look and J. H. Leach, J. Vac. Sci. Technol. B
34(4), 04J105 (2016).
Direct Measurement of Junction Capacitance in the Perovskite Solar Cells
Authors: Uchida Satoshi , Tobita Hiromi , Nonomura Kazuteru , Jayaweera Piyankarage Viraj Vishwakantha , Kaneko Shoji , Cojocaru Ludmila , Segawa Hiroshi 
Published: December 2020

Introduction

Organic–inorganic halide perovskite solar cell has great attention for its high performance together with easy production and wide variety of the process & flexibility of substrate materials. Here in this research the results of capacitance measurement inside the perovskite device is discussed.

Experimental

The capacitance of perovskite solar cell was measured by Capacitance Analyzer (VMK-8000 & VK-CA-1000, SPD Inc.) specially designed for our purpose.

Results and Discussion

Figure 1(upper) shows the constant current charge-discharge testing protocol for the direct measurement of capacitance. Differ from the conventional AC mode impedance analysis, this technique provides the direct capacitance in DC mode without the effect of measuring frequency and the interpretation of equivalent circuit model.
Figure 2(lower) shows the change of capacitance and I-V curves of perovskite solar cell before & after 1 sun irradiation aging. The resulting cell performances are as follows. Before aging; Eff=10.4(forward) Eff=12.4(reverse). After aging; Eff=13.5(forward) Eff=15.1(reverse). The change of capacitances are as follows. Before aging; 30.9μF. After aging; 32.5μF. Due to the definition, the change of the capacitance may came from the change of physical gap in between TiO2 layer and perovskite layer.
Further chemical and physical properties of these solar cells will also be discussed in related with crystallographic change.

Figure 1
(Invited) Progress in Materials and Process of Perovskite Solar Cells Toward Commercialization
Authors: Jung Hyun Suk 
Published: December 2020

All solid-state solar cells based on organometal trihalide perovskite absorbers have already achieved distinguished power conversion efficiency (PCE) to over 25% and further improvements are expected up to 27%. Now, the research on perovskite solar cells has been moving toward commercialization. To facilitate commercialization of these great solar cells, some technical issues such as long-term stability, large scale fabrication process, and Pb-related hazardous materials need to be solved. Also, flexible perovskite solar cell using plastic substrate can be used in niche applications such as portable electrical chargers, electronic textiles, and large-scale industrial roofing.
This talk is dealing with our recent efforts to facilitate commercialization of perovskite solar cells. For examples, we introduce a recycling technology of perovskite solar cells, which covers the regeneration process of Pb contained perovskite layer as well as recycling process of Au electrodes and transparent conducting oxide glass. Also, recent interesting results regarding ultra-flexible perovskite cells will be discussed in terms of stress analysis. Finally, simple fabrication technologies for realizing large scale perovskite module is going to be introduced.
Realization of Separated Imprinting Fabrication Process Driven from Interfacial Wetting Mechanism for Durable Perovskite and Organic Photovoltaic Devices
Authors: Jang Woongsik , Cho Jae Sang , Kim Minsu , WANG DONG Hwan H. 
Published: December 2020

Recently, fabrication procedure has become a key factor directly related to the efficiency and cost reduction of products. Despite the importance of process improvement, due to the limitations of the application range, many fabrication processes are limited to laminating one by one. Particularly, when applied to a roll-to-roll process, since the only method is to increase the length of the rail for heat treatment and drying time, realization of the separated fabrication process can minimize waste. One of the separated imprinting processes, transfer process using by soft mold, has been considered by advanced technology to overcome limits of conventional lamination process (spin-casting, dip-coating, etc.), because a layer is previously formed on the other medium substrate, as well as the material loss and penetration of solvents are minimized in the process.
In this research, we introduced polyurethane acylate (PUA) of which the surface property was modified by applying the various functional group of the monomer, because control of the surface property of the medium was required to minimize interfacial wettability with a material. As a result, we designed the proper PUAs to enable the transfer process of each organic semiconductor via adhesion control between each interface. First, we applied the transfer process to inter-layer in planer-type perovskite photovoltaics. We successfully transferred two types of inter-layer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) [1], and 6,6-phenyl-C71 butyric acid methyl ester (PC71BM) [2]. Interestingly, when the PEDOT:PSS was transferred onto Indium tin oxide (ITO) substrate, the corrosion of ITO was extremely suppressed due to solid-state film formation, which enhanced the stability of the perovskite devices. Especially, the device with transferred PC71BM exhibited the performance improvement caused by improved coverage of inter-layer on perovskite layer, correlated with increased electron mobility and exciton dissociation. Finally, the transfer process was introduced to organic photodiode (OPD) fabrication [3]. Despite the separated imprinting system, a comparable performance was confirmed in the OPD from the transfer process. Furthermore, the OPD with transferred sensitive layer showed a superior durability (over 95%) to the device from conventional process, owing to morphology stabilization of organic semiconductor layers. This work provides a strategy for promising next-generation technologies of separated imprinting fabrication process, and at the same time can make a significant contribution to increase of process yield and reduction of unit prices.
[1] M. Yi, W. Jang, J. S. Cho, and D. H. Wang, Appl. Surf. Sci., 2019, 467, 168.
[2] S. Ahn, W. Jang, S. Park, and D. H. Wang, ACS Appl. Mater. Interfaces, 2017, 9, 15623.
[3] W. Jang, and D. H. Wang, ACS Appl. Mater. Interfaces, 2018, 10, 38603.
Characteristics and Applications of CAAC-IGZO FET with Gate Length of 13nm
Authors: Suzuki Akio , Yuichi Yanagisawa , Mizukami Shota , Tsuda Kazuki , Ito Minato , Ohshima Kazuaki , Matsumoto Noriko , Yakubo Yuto , Miyata Shoki , Okuno Naoki , Kunitake Hitoshi , Sasagawa Shinya , Ikeda Takayuki , Yamazaki Shunpei 
Published: December 2020

A field-effect transistor (FET) using CAAC-IGZO, a crystalline oxide semiconductor having a c-axis alignment, is considered for application to various circuits. In particular, its extremely low off-state leakage current[1,2] enables design of non-volatile memory and analog memory devices[3], allowing AI tasks to be run in non-von-Neumann architectures. Furthermore, CAAC-IGZO FET can be applied to use cases other than memory, such as RF applications. CAAC-IGZO FET can be integrated in the back-end-of-line processes of CMOS technologies[4], and allows higher power supply voltages than conventional CMOS devices[4]. This may contribute to reduced chip area, which can create smaller packages, which are demanded for IoT endpoints.
As there are not many applications that currently use scaled CAAC-IGZO FET, CAAC-IGZO FET is not yet applied to quasi-millimeter-wave applications. In addition, circuit design for high-frequency applications of CAAC-IGZO FETs will require extraction of FET characteristics that will be utilized in this application. Compact models are available for large IGZO FETs [5], but not for scaled CAAC-IGZO FETs.
For this work, we have prototyped and evaluated scaled CAAC-IGZO FETs (Fig. 1(a)) that are suitable for high-frequency applications in addition to memory applications. From network measurements, it was found that the CAAC-IGZO FET exhibits a cutoff frequency of 60 GHz (Fig. 1(b)) and a maximum oscillation frequency of 16 GHz, which is promising for quasi-millimeter-wave designs.
In addition, we have designed equivalent circuits of the scaled CAAC-IGZO FET using linear devices. This circuit shows not only the characteristics of the scaled CAAC-IGZO FET, but also the potential for circuit designs with the device.
This work compiles the characteristics of the scaled CAAC-IGZO FET, and proposes a novel circuit application for the device.
Fig. 1 (a) L-direction cross section of the scaled CAAC-IGZO FET.
(b) Network measurment result of the scaled CAAC-IGZO FET

References

[1] N. Kimizuka and S. Yamazaki, “Physics and Technology of Crystalline Oxide Semiconductor CAAC-IGZO FUNDAMENTALS,” WILEY, 2017.
[2] S. Yamazaki and M. Fujita, “Physics and Technology of Crystalline Oxide Semiconductor CAAC-IGZO Application to LSI,” WILEY, 2017.
[3] Y. Kurokawa et al., JJAP, vol. 59, pp. (SGGB03-1)-(SGGB03-11), 2020.
[4] H. Kunitake et al., J-EDS, vol. 7, pp.495-502, 2019.
[5] L. J. Giacoletto et al., JSSC, vol. 4, issue 2, pp.80-83, 1969.

Figure 1