bluuebunny/crossref_metadata_2025 huggingface dataset:
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.

C. P. Grey and J. M. Tarascon, Nature Materials, 2017, 16, 45

G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson and W. Wilcke, The Journal of Physical Chemistry Letters, 2010, 1, 2193

D. Aurbach, B. D. McCloskey, L. F. Nazar and P. G. Bruce, Nature Energy, 2016, 1, 16128.

D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, MRS Bulletin, 2014, 39, 443.

N. Mahne, B. Schafzahl, C. Leypold, M. Leypold, S. Grumm, A. Leitgeb, Gernot A. Strohmeier, M. Wilkening, O. Fontaine, D. Kramer, C. Slugovc, Sergey M. Borisov and Stefan A. Freunberger, Nature Energy, 2017, 2, 17036.

T. Liu, M. Leskes, W. Yu, A. J. Moore, L. Zhou, P. M. Bayley, G. Kim and C. P. Grey, Science, 2015, 350, 530.

C. M. Burke, R. Black, I. R. Kochetkov, V. Giordani, D. Addison, L. F. Nazar and B. D. McCloskey, ACS Energy Letters, 2016, 1, 747.

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

Figure 1
(Invited) Two Dimensional (2D) Materials for Interfacial Engineering and Polymer Electrolyte Composites in Li/Zn Metal Batteries
Authors: Shahbazian-Yassar Reza
Published: December 2020

Two dimensional (2D) materials have promising properties to regulate the ion transport across interfaces and within the electrolyte, act as substrate for metal deposition, and reduce the occurrence of dendrites. In this presentation, I will showcase our efforts in utilizing graphene, graphene oxide, phosphorene, and boron nitride nanosheets in design of rechargeable Zn and Li metal batteries. We have observed that graphene oxide materials coated on separators can regulate the transport of Li ions across the Cu-electrolyte interface evident by far less dendritic deposition of Li in comparison to non-coated Cu cells. In addition, graphene is shown to control the deposition of Zn due to minimal lattice mismatch with Zn and the zincophilic properties (strong bonding with Zn). The utilization of phosphorene in PEO-based polymer electrolytes also is shown to increase the fraction of free Li ions resulting in better ionic conductivity and low interfacial resistance. In another work, we have shown the BN nanosheets are effective in controlling the thermal conductivity in solid polymer electrolytes leading to the lesser chance of local hot spots creation in polymer batteries.
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).
(Invited) Progress with Crystalline Silicon Solar Cells and Modules at SERIS
Authors: Aberle Armin Gerhard
Published: December 2020

Despite their maturity and market dominance, crystalline silicon (c-Si) solar cells and modules continue to develop rapidly, with increasing efficiencies and reducing cost ($/W). This contribution describes recent progress at SERIS with industrially relevant crystalline silicon solar cells and modules, covering both p-type and n-type cells. Since the costs of the solar cells and modules as a proportion of the costs of complete PV systems continue to fall, a premium is placed on cell efficiency as this reduces the balance of system (BOS) cost (in $/W) of PV systems. Thus, cost-effective monocrystalline high-efficiency silicon solar cells such as SERIS’ 23.5% efficient passivated-contact technology (“monoPolyTM”) have enormous market potential. Good progress is also being made in the SERIS laboratory with small-area perovskite/silicon tandem solar cells, giving efficiencies of over 25% in 4-terminal configuration.

Keywords: Solar energy, photovoltaic devices, crystalline silicon solar cells, PERC solar cell, monoPolyTM solar cell, passivated contacts, perovskite solar cells, perovskite/silicon tandem solar cells.
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.
Development of High Efficiency, Stability Electrolyte for Dye-Sensitive Solar Cells Using Ionic-Liquid
Authors: Yoo Kicheon , Kang Hyeong Cheol , Nath Narayan Chandra Deb , Lee Jae-Joon
Published: December 2020

Dye-Sensitized Solar Cell (DSSC) has some unique properties such as transparency with various colors, easy fabrication processes, and relatively high and steady energy conversion efficiencies, compared to other type of solar cells. Energy conversion efficiencies above 11 % and 13 % have been achieved for cells with volatile liquid- based organic solvents. However, the utilization of liquid electrolytes is often considered as a major causes of significant leakage problems during operation. To overcome disadvantages of liquid- based electrolytes, we used Ionic-liquid which has low viscosity and volatility. Here we report a ionic-liquid-based electrolyte containing 1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIM-TFSI), 1-Ethyl-2-methylimidazolium tetrafluoroborate (EMIM-BF4), which satisfies both the high efficiency, stability and high transmittance against leakage. An ionic liquid electrolyte composed of EMIM-TFSI and EMIM-BF4 was combined with and electrolyte solvent (acetonitrile, 3-methoxypropionitrile, valeronitrile) to obtain a solar cell based on a liquid electrolyte. The power conversion efficiency of the DSSCs employing ionic liquid blend electrolytes (PMII, Iodine, GuSCN, tBP, sovent ;3-methyloxypropionitrile; EMIM-TFSI = 7:3) and the transmittance of ionic liquid blen electrolytes were 5.74 % (open-ciruit voltage Voc = 0.74 V , short-circuit current density Jsc = 12.08 mA/cm2 and fill factor FF = 0.64) 75.8 %, which was similar to DSSCs with organic liquid-based electrolytes ( PMII, Iodine, GuSCN, tBP, sovent ;3-methyloxypropionitrile) (η = 5.76%, Voc = 0.75 V, Jsc = 12.30 mA/cm2 and FF = 0.63, Transmittance = 74.3%), However, the vapor pressure of these ionic liquid blend electrolytes (PMII, Iodine, GuSCN, tBP, sovent ;3-methyloxypropionitrile; EMIM-TFSI = 7:3) was 1.25 Hg at 80℃ which was similar to the cells with the electrolytes employing ionic liquid only (PMII, Iodine, GuSCN, tBP, EMIM-TFSI (vapor pressure = 1.21 at 80℃).
Development of Highly Transparent Dye-Sensitized Solar Cell Module
Authors: Kang Hyeong Cheol , Yoo Kicheon , Kim Jae Cheon , Lee Jae-Joon
Published: December 2020

Dye-sensitized solar cell (DSSC) processes transparent, colorful, and flexible architectures that have attracted significant interest in terms of newly emerging see-through photovoltaic windows. In this study, we developed transparent TiO2 and Pt counter electrodes to fabricate DSSC module with high transparency and power conversion efficiency (PCE). The TiO2 nanoparticles having sizes from 14 to 30 nm were prepared by the variation of the TiO2 precursor content and by controlling the synthetic conditions for highly transparent pastes. The transmittance of all TiO2 films were superior to those prepared by commercial pastes with the identical thickness. In addition, we prepared paste of TiO2 blocking layer by controlling the Ti precursor/vehicle. The as-prepared TiO2 blocking layer with screen-printing process exhibited a transmittance of ca. 77.59%, which is superior than those prepared by the conventional spin-coating (74.79%) and dip- coating (71.14%) of the precursors. Furthermore, highly transparent and screen-printable Pt paste for counter electrode was also developed by controlling the Pt precursor. The transmittance of as-prepared Pt counter electrode (75.3%) was higher than the conventional one with spin-coating method (69.3%). Then, DSSC module(Z-type) with the active area of 100.8 cm2 that have Red, Green and Blue colors(N719,N749,SGT-140) showed a PCE of ca. 7.0 %, 5.5%, 4.2% with Isc of 0.1A, 0.08A, 0.1A Voc of 12.3 V, 9.6V, 8.4V FF of 67.8%, 72.2%, 52% and the transmittance reached up to 30%.
Enhanced Operating Temperature Stability of Organic Solar Cells with Metal Oxide Hole Extraction Layer
Authors: Kim JunYoung
Published: December 2020

Organic solar cells (OSCs) are promising renewable energy sources for replacing fossil fuels. The power conversion eciency (PCE) of OSCs has increased based on tremendous eort in material and device engineering. Still, the stability of OSC, such as long lifetime, negative temperature coecient, must be enhanced for commercialization. In this study, we investigated OSC performance at a high operating temperature near 300–420 K, which are typical temperature regions in photovoltaic applications, with a dierent hole-extraction layer (HEL). The metal oxide-based HEL, MoO3, exhibited stable operating properties with a PCE drop rate of -0.13%/C, as compared to polymeric HEL, PEDOT:PSS (-0.20%/C). This performance reduction of polymeric HEL originated from the degradation of the interface in contact with PEDOT:PSS, as compared to the robust inorganic metal oxide HEL.
Water Oxidation Reaction Catalyzed By Cobalt Incorporated Hydroxyapatite
Authors: Kwon Ki-Young
Published: December 2020

We synthesized hydroxyapatite containing cobalt ion and characterized electrochemical catalytic properties. The cobalt quantity analyzed by ICP-AES was approximately 1 wt%. The XRD patterns of catalyst was almost identical to the those of hydroxyapatite. And EDX mapping measurements show that cobalt species are well dispersed on the surface of catalyst. Therefore, we suggest that cobalt ions are randomly doped on the catalyst surface. The cyclic voltammetry of catalyst exhibits a weak oxidation wave at 1.10 V vs NHE. After bulk electrolysis 3 hours, the current density raised more than twice times. The evolution of hydrogen and oxygen was characterized by gas chromatography. The faradaic efficiency was calculated to be 95 %. The stability test by bulk electrolysis showed that the catalytic activity was maintained for more than 12 hours.
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
Influence of Glass Surface Modification on Thin Film Copper Electrodes
Authors: Huang Ming-Huang , Shi Ying , Zhu Bin , Vaddi Rajesh , Kim Hoon , Manley Robert G.
Published: December 2020

Large-area and ultra-high resolution displays continue to progress driven by new performance requirements and applications. As display sizes become larger, the industry demands metal electrodes with low resistance to reduce the gate delay time and signal distortion. Cu is an attractive candidate due to its relative low resistivity and its superior resistance to electromigration as opposed to materials such as Al or Mo. For bottom gate TFT technologies, the metal electrode is deposited directly on the glass substrate. Cu is known to have poor adhesion with oxide materials such as the substrate glass. Typically, an adhesion layer such as Ti, Mo, or other metal/alloy is required to improve the adhesion of Cu to the substrate. In this work, we modify Corning® Eagle XG® glass surfaces by various treatments to study the impact of the glass surface on the structural and electrical properties of Cu. Ti was used the adhesion layer in this study. Atomic force microscopy is used to examine the surface topography and the surface roughness of Cu. In-plane X-ray diffraction results characterize the crystallization and crystalline in-plane orientation of Cu. Transmission electron microscopy is used to further investigate the structure of the Ti and Cu films. The films properties are correlated with 4-point probe measurement of the sheet resistance. The film adhesion performance is determined using the tape test. The role of the glass surface state is demonstrated through its impact on the structural and electrical properties of Ti/Cu electrodes emanating from glass surface treatments.
Stretching Compensation Pixel Circuit Based on Oxide Thin Film Transistor
Authors: Kim Seo Gwon , Kang In Hye , Kang Seok Jun , Woo Jae Geun , Bae Byung Seong
Published: December 2020

Thin film transistors (TFTs) are the essential elements to implement active matrix organic light-emitting diode (AMOLED) display. The TFT on the AMOLED controls the emission of the OLED. Pixel circuits are being studied to improve the display quality. Poly-crystalline silicon TFT and oxide TFT have been manufactured and integrated on glass substrates for AMOLED. Various kinds of display such as foldable, rollable, wearable and stretchable displays are being studied.

In stretchable displays, the device and wires manufactured on the substrate are stretched out. The resistances of wire, parasitic capacitances are affected by stretching of the substrate. In addition, when the substrate is stretched, electrical characteristic such as threshold voltage and mobility of TFT would be able to change, which results in the luminance change of the OLED. Therefore, analysis of changes in TFT is required when the substrate is stretched, and compensation circuits are required. In this study, the compensation pixel circuit is proposed for the stretchable display.

To make the circuit, IGZO was used as an active layer of the TFT and deposition by RF magnetron sputter. Insulator layer was deposited for the gate insulator using atomic layer deposition (ALD) and inter layer dielectric was formed after doping of the source-drain region in the same way after doping of the source-drain region.
Surface Energy Characterized Self-Assembled Monolayer for Improving Electrical Stability of IGZO Thin Film Transistor
Authors: Lee Sung-Eun , Na Hyun-Jae , Park Jintaek , Lee Eun Goo , Kim Kyungho , Lee Jaehak , Kim Youn Sang
Published: December 2020

The surface energy characterized self-assembled monolayer (SAM) for improving the electrical stability of Indium gallium zinc oxide (IGZO) semiconductor is proposed. In order to compare properly, the head group and body group were fixed with silane and alkyl chains, respectively, and only the functional group was changed, NH2, CH3, CF3 respectively. The surface energies of NH2, CH3 and CF3 functional group SAMs were measured as 50 mJ/m2, 29 mJ/m2 and 24 mJ/m2, respectively by Owens-Wendt model with the contact angle values. The SAM treatment for IGZO TFT backchannel passivation amazingly improves the positive bias stability (PBS) and clockwise hysteresis stability to the very similar tendency by making oxygen-related molecules difficult to be adsorbed onto IGZO backchannel depending on the surface energies of SAMs. In case of NH2 SAM treated IGZO TFT, the PBS improvement ratio by the treatment was 78.7 % (from 11.6 V to 2.5 V) and the clockwise hysteresis improvement ratio was 70.5 % (from 0.8 V to 0.2 V). Furthermore, it was confirmed that the better result was obtained at a lower surface energy functional group. The IGZO TFT PBS further improved 87.0 % after the lowest surface energy with CF3 SAM treatment (from 2.5 V to 0.3 V), and the IGZO TFT clockwise hysteresis was also further enhanced 52.2 % (from 0.2 V to 0.1 V) without any deterioration of TFT characteristics. The field-effect mobility and sub-threshold swing of the IGZO reference TFT with non-SAM treated were 11.2 cm2 / Vs and 0.2 V / decade, respectively. NH2, CH3, and CF3 functional group SAM treated IGZO TFTs show the field-effect mobility of 13.5 cm2 / Vs, 13.0 cm2 / Vs, 13.1 cm2 / Vs, and sub-threshold swing of 0.18 V / decade, 0.20 V / decade, 0.18 V / decade, respectively. As a result, the simple and economical SAM treatment with lower surface energy functional group surface at same head and body group can be a better way in passivating and protecting the IGZO backchannel region from oxygen molecules in the atmosphere in order to enhance the electrical stability of IGZO TFT.

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(Invited) Laser-Engraved Lab on the Skin for Metabolic and Nutritional Monitoring
Authors: Gao Wei
Published: December 2020

Wearable sensors offer tremendous potential for biomedical applications. Sweat analysis is an attractive candidate that enables continuous and non-invasive molecular monitoring of circulating metabolites and nutrients. However, existing wearable sweat sensing platforms are primarily focused on a limited number of electrolytes and metabolites monitored via ion selective or enzymatic electrodes. Moreover, they either lack multimodal sensing functionality or require expensive micro/nanofabrication facilities. Here we report a mass-producible, all-laser-engraved graphene sensor that enables highly sensitive sweat analysis and multiplexed vital sign monitoring. We demonstrate in situ continuous uric acid and tyrosine monitoring in human perspiration during exercise in both physically trained and untrained subjects. The use of this platform for non-invasive gout management is evaluated on clinically diagnosed gout patients and via a purine-rich meal challenge on healthy individuals. This flexible graphene sensor demonstrates great promise for non-invasive, personalized metabolic and nutritional management.
WSe2 Homogeneous in-Plane Pin Junction Diode with Electric Double Layers
Authors: Choi Wonjun , Ahn Jongtae , Im Seongil , Jeong Yeonsu
Published: December 2020

Transition metal dichalcogenide (TMDC) materials are in the spotlight as next-generation semiconductor materials because of their advantages over other semiconductor materials. Research on WSe2 among the materials is underway, and the feature of WSe2 has an ambipolar characteristic, and the fermi level change and the doping effect are different according to the electrode type.

In the present study, we have fabricated a homogeneous WSe2 PIN junction diode. Our in-plane multilayer WSe2 p-i-n homogeneous diode exhibited photovoltaic properties by asymmetric physical contact doping effect with electric double layer(EDL). Owing to the EDL placed between the cathode and anode, local charge carrier type and density profile are modulated in the same layers.

Compared to general diode mode, PIN mode enhance the photo response of the device in our visible measurement range. The diode exhibits excellent rectifying behavior with a current rectification ratio of 104 or higher. Photovoltaic performance of short circuit current and open circuit voltage achieved 3.2 nA, 0.55 V, respectively under the 550 nm green light. And spectrum responsivity is about ~100 mA/W (max point) at 3.2 eV to 1.6 eV.

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High Responsivity Photodetector at Room Temperature Based on Pure-Phase 2-D InAs Nanosheets
Authors: Wang Xinzhe , Chen Qing
Published: December 2020

Low-dimensional narrow-band-gap III-V semiconductors are the key component of next generation high-performance nanoelectronics, nanophotonics and quantum devices. However, high-performance nanoscale wide-spectrum photodetectors covering IR range are still rare. Here, we report a new kind of photodetector based on 2-D InAs nanosheets. Figure (a) shows that the morphology of the 2-D InAs nanosheet was characterized by transmission electron microscopy. The photodetector has a very high optoelectronic response in the infrared band at room temperature. As shown in Figure (b), the devices can respond to light with wavelength ranging from 650 to 1100 nm of IR with high responsivity. The high performance of photodetectors is mainly reflected in the ultra-high responsivity (~1231A/W), ultra-high EQE (2.2 x 105 %) under 700nm wavelength laser illumination, and very low operating voltage. These results show that the 2-D InAs nanosheets devices have broad application prospects in nanoelectronic devices, optoelectronic devices and integrated optoelectronic devices.

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(Invited) Liquid Phase Interfacial Assemblies of Porous Nanosheets with Controlled Orientation and Thickness
Authors: Makiura Rie
Published: December 2020

Development of rational methods for creating ordered two-dimensional (2D) structures with nanometer scale precision is one of the central issues in the nanoscience and nanotechnology fields because of their intrinsic physical-chemical properties which are seen in those of their equivalent bulk state. Inclusion of highly regulated nanopores into the nanosheet structure will further open the possible applications such as nanosieves, molecular/ion storage and sensor devices as well as introducing guest molecules into the nanopores tune variedly the sheet properties (electric conduction, nanoheterojunction). Utilizing molecular building units are suitable for creating such porous nanosheets because of rich variety of design and facile modification of size and shape. Furthermore, various chemical interactions such as covalent bond, coordination and hydrogen bond are applied for assembling molecular-based nanosheets.

Here, I present a facile bottom-up synthesis of molecular nanosheets with both positional and size regulated nanopores utilizing air/liquid interfaces. By applying liquid interfaces, growth direction of the object can be well controlled with utilizing self-assembly feature of the molecules under mild conditions. We have succeeded to tune finely the nanosheet structures by rational modification of molecular building units [1-4]. In addition, new methodology we developed based on the liquid interface technique resulted in enlarging the nanosheet size. The highly crystalline structure remains after transferring a solid substrate from the liquid surface as well as without any supports. Notably, such highly oriented porous crystalline structure is obtained specifically by applying bottom up synthesis at air/liquid interfaces, not by other techniques such as drop cast [5].

Makiura, R. et al. Nature Mater. 9, 565 (2010).

Motoyama, R. Makiura, O. Sakata, H. Kitagawa, J. Am. Chem. Soc. 133, 5640 (2011).

Makiura, R., Konovalov, O. Rep. 3, 2506 (2013).

Makiura, R. et al. ChemPlusChem. 79, 1352 (2014).

Makiura, R. et al. ACS Nano,
11, 10875–10882 (2017).

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(Keynote) Functional 2D Conjugated Polymers By Interfacial Synthesis
Authors: Dong Renhao
Published: December 2020

The discovery of graphene one decade ago has triggered enormous interest in developing chemistry of synthetic two-dimensional materials (2DMs). In our work, we have employed interfacial chemistry toward the controlled synthesis of organic 2DMs with diverse structures and functions.[1] For instance, we demonstrated the synthesis of 2D conjugated metal-organic framework (2D c-MOF) at the air-water or liquid-liquid interfaces. The 2D c-MOFs feature with stacked layers and possess unique electronic properties, such as full π delocalization, narrowed band gaps, high conductivity and high mobility, which render 2D c-MOFs as advanced electronic materials. One representative iron-bis(dithiolene) 2D MOF exhibited as a p-type semiconductor with a band-like transport and high mobility of ~220 cm2/Vs.[2] Owing to their conductivity, the 2D c-MOFs have shown potential for transistors, photodetectors, sensing, magnetics, and energy storage and conversion.[1,3,4] Besides the coordination polymer, we have also synthesized conjugated 2D covalent polymers at the air-water or liquid-liquid interfaces. In our latest work, we have employed a surfactant-monolayer-assisted interfacial synthesis (SMAIS) method to prepare 2D polymers, like 2D polyimides and 2D polyimines, which exhibit few-layers and micrometer-sized single-crystalline domains.[5] In short, we expect to develop interfacial chemistry methodologies toward the controlled synthesis of organic 2DMs and achieve delineation of reliable structure-property relationships and superior physical and chemical performances of organic 2DMs.

References

[1] R. Dong, et al., Chem. Rev. 2018, 118, 6189-6235.

[2] R. Dong, et al., Nat. Mater. 2018, 17, 1027-1032.

[3] a) R. Dong, et al., Nat. Commun. 2018, 9, 2637; b) C. Yang, et al., Nat. Commun. 2019, 10, 3260.

[4] H. Zhong, et al., Angew. Chem. Int. Ed. 2019, 58, 10677-10682.

[5] K. Liu, et al., Nat. Chem. 2019, 11, 994-1000.
Synthesis and Supercapacitive Properties of Ni/Co-S Derived from MOF-74
Authors: Pang Xiancai , Gao Xiaolei , Li Xu , Yu Jianhua , Zhang Qian , Sui Lina , Dong Lifeng
Published: December 2020

Supercapacitors have been considered as one of the most promising energy storage devices for developing renewable energy resources with the increasing demands of energy and environmental protection. Binary transition metal sulfides have captured tremendous research interests in the field of supercapacitors due to their intrinsically high electrical conductivity and superior capacitive properties. In this work, the MOF-74 with Ni, Co and different ratios of Ni/Co (2:3, 1:1, 3:2) was synthesized by a facile solvothermal method, and then adopted as templates to derive Ni3S4, Co3S4 and NiCo sulfides by a heat treatment and subsequently solvothermal sulphidation. Electrochemical measurements show that the obtained rod-like sulfides have excellent capacitance properties. Notably, Co3S4 exhibits a high specific capacitance of 1843 F g-1 at 1 A g-1, which decreases to 930 F g-1 at 20 A g-1 with a retention of around 50%. While NiCo-S derived from NiCo-MOF-74 (Ni/Co=2:3) displays superior specific capacitances of 1910 F g-1 and 1160 F g-1 at 1 A g-1 and 20 A g-1, respectively, with a retention of above 60%. This clearly demonstrates that compared with Co3S4, NiCo-S has a higher specific capacitance and a better rate capability, which can be attributed to synergistic effects accompanying with the introduction of Ni.
(Invited) Atomic Layer Deposition of MOF from Dissolved Precursors ― ‘Solution ALD’ (sALD)
Authors: Barr Maissa K. S. , Nadiri Soheila , Chen Dong-Hui , Weidler Peter G. , Baumgart Helmut - , Redel Engelbert , Asker Ceyla , Forberich Karen , Hoga Felix , Stubhan Tobias , Egelhaaf Hans , Brabec Christoph , Bachmann Julien
Published: December 2020

Metal organic frameworks (MOFs) are crystalline three-dimensional porous solids featuring a high surface area, which have attracted considerable attention in a wide range of applications e.g. in catalysis, hydrogen storage, gas separation, thermoelectric applications or as chemical sensors. Beyond solvothermal synthesis of bulk MOF crystals, growing MOFs thin films has been limited so far to rather conventional solution-based techniques. However, traditional growth methods from solution such as spin-coating, spray-coating or dip-coating generate MOFs thin films with a rather low film quality and an alarming lack of a precise film thickness control under 1 nm. This renders them unsuitable for most industrial applications and severely limits their future application potential.

Atomic layer deposition (ALD) provides this capability, but is limited by the necessity to use gaseous precursors in vacuum conditions at temperatures typically above 100°C. This is incompatible with the typically high temperature sensitivity of many hybrid metal-organic compounds such as the MOFs.

In this perspective, we have transferred the principles of ALD to precursors dissolved in liquid solvents. The ‘solution ALD’ (sALD) method can be implemented in a variety of microfluidic or slot-die processing devices. We have demonstrated that the principles of classical, gas-based ALD —self-limiting surface reactions— are reproduced in sALD. sALD shares the fundamental properties of standard ‘gas ALD’ (gALD), in particular the self-limiting surface chemistry and the ability to coat deep pores in a conformal manner Furthermore, sALD allows the experimentalist to design new, advantageous, reactions of known semiconductors (oxides, heavier chalcogenides), or to deposit materials otherwise inaccessible to ALD altogether, such as polymers, ionic solids, and metal-organic frameworks. They may be obtained in highly pure, crystalline form at room temperature, either as planar films or as conformal coatings of porous substrates. Based on these advances, we have been able to make the first sALD-derived films of a MOF, Cu-BDC. At any chosen thickness, sALD MOF films feature significantly lower roughness and better adhesion than those generated by the best spray-coating and dip-coating methods available currently.
(Invited) Molecular Engineering of Conductive Framework Materials for Electroanalysis
Authors: Mirica Katherine A.
Published: December 2020

Electronically-transduced chemical sensors have the potential to enhance healthcare through improved understanding of human behavior, assessment of stress, early diagnosis, and treatment of disorders. Electrochemically active and conductive framework materials—metal–organic frameworks (MOFs) and covalent organic frameworks (COFs)—constitute an emerging class of multifunctional sensing materials with remarkable properties that can help address global challenges in healthcare. This class of materials is uniquely accessible through bottom-up self-assembly from extremely modular molecular building blocks, which can enable atomically-precise synthetic control over emergent and synergistically-integrated structure–property relationships in the solid state. Bolstered by fundamental spectroscopic analysis of material-analyte interactions, this presentation will highlight the broad potential of conductive framework materials as versatile and integral components within portable electroanalytical devices.

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