bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Using High Frequency Impedance Measurements for Phase Wetting Detection and Water Layer Thickness Characterization in Two-Phase Oil-Water Flow
Authors: Paolinelli Luciano , Nesic Srdjan , Juncheng Yao , Rashedi Ahmadreza
Published: February 2020

Two-phase oil-water pipe flow is common in oil and gas production. When transported water comes in contact with pipeline walls, water wetting results and severe internal corrosion can occur. Water wetting can be avoided by disrupting and entraining the water phase into the oil phase. Consequently, it is of great interest to know under which operating conditions this happens. Various experimental studies have been performed in order to investigate water wetting in oil-water pipe flow. Most often, two-electrode DC conductance measurements have been used to detect water wetting. Despite the relative success of the present implementation, the DC analytical setup is not straightforward to deploy as it requires extensive calibration, due to the complicating effect of the electrochemical reactions occurring at electrode surfaces. Moreover, as the conductance of the water phase cannot be measured reliably this way, estimation of important geometric characteristics, such as the thickness of water layer, is not possible either. In the present work, high frequency impedance measurements were made using a flush mounted two-electrode concentric probe, in order to detect phase wetting regimes in large-scale oil-water pipe flow, as well as to determine the water layer thickness associated with water wetting. Theoretical formulations to correlate the resistance of sensed water layers with their actual thickness are introduced and experimentally validated. Excellent results in terms of phase wetting detection and characterization of water layer thickness are obtained.
Monitoring of Corrosion Resistance of Steel in Simulated Concreate Pore Solution By EIS
Authors: Okamoto Tatsuki , Tokieda Hiroyuki , Hoshi Yoshinao , Shitanda Isao , Itagaki Masayuki
Published: February 2020

The method to evaluate the reinforcing steel in concreate have been investigated because the degradation of reinforced concrete is a serious problem in the whole world. An electrochemical impedance spectroscopy (EIS) is the powerful tool to determine the condition of the reinforcing steel in concrete because it is possible to obtain the electrochemical parameters of the reinforcing steel in concrete without its destruction by EIS. Dawson et al. [1] applied EIS to the investigation of corrosion of rebar in concrete. In the present study, we proposed the method to determine the corrosion resistance of reinforcing steel in concrete using the cylindrical steel probes by EIS. Figure 1 shows the cylindrical steel probes developed in the present study. The diameter and thickness of the steel probe is 10 mm and 8 mm respectively. The distance between the steel probes are 50 mm. These probes are embedded in concreate with the reinforcing steel. We expect that the corrosion resistance of the reinforcing steel in concreate can be determined by monitoring of the electrochemical impedance of the cylindrical steel probes.

In order to establish the proposed monitoring method, the electrochemical impedance of the cylindrical steel probes were measured in the simulated concreate pore solution. Figure 2 shows the experimental setup of the electrochemical impedance measurement of the cylindrical steel probes in Fig. 1. The electrolyte solution was the saturated Ca(OH)2. The cylindrical steel probes were immersed in the electrolyte solution for 2 days. The air was continuously provided by pump during the immersion of the cylindrical steel probes in the electrolyte solution. The electrochemical impedance was automatically monitored at 10 kHz and 10 mHz using a corrosion monitor (Corp. i-pec, CEM-100A) by two electrode system. The potential amplitude was 10 mV. In addition, the electrochemical impedance measurement was carried out using the Potentiostat (Toyo Corp., Solatron1287) and FRA (Toyo Corp., Solatron1255B) in the frequency range from 10 mHz to 10 kHz at five frequencies per decade with AC amplitude of 10 mV. The pH of the electrolyte solution was measured every 24 hours.

The electrochemical impedance of the cylindrical steel probes determined using the corrosion monitor was compared to that measured using FRA. The changes of the charge transfer resistance R
ct was discussed by the time variation of pH.

Reference

[1]　J. Dawson, L. Callow, K. Hladky and J. Richardson, Corrosion/78, 125 (1978).

Figure 1
Lithium Battery Start-Ups
Authors: Balsara Nitash P
Published: February 2020

Lithium-ion batteries, developed for powering consumer electronics, are being reconfigured for use in electric vehicles, and for backing-up home solar installations. The adoption of batteries in large-scale applications will accelerate if some of the key limitations of current lithium-ion technology can be addressed: cost, energy density, cycle-life, and safety. In spite of these limitations, the growth of lithium-ion battery industry is noteworthy. Tesla, a relatively small car company in California, is gearing up to build a factory that will produce 50% of lithium batteries worldwide. Today virtually every major car company has a stake in the electric car arena. An important milestone for improving lithium batteries is the quest to replace the graphite anode by lithium metal. In 2007, Hany Eitouni and Mohit Singh, and I founded a company called Seeo to commercialize all-solid batteries with a lithium metal anode. It was based on stabilizing the lithium anode using a block copolymer electrolyte developed by Singh and Eitouni when they were students in my lab. In 2007, enabling the lithium metal anode was not high on the priority list of major battery manufacturers. It was thus difficult to engage in meaningful partnerships with them. The situation is different today. While difficulties surrounding the lithium metal anode are widely recognized, enabling it represents the most credible path for increasing the specific energy of lithium batteries substantially beyond that of lithium-ion chemistry. Cells with specific energies comparable to gasoline such as lithium-sulfur and lithium-air are all dependent on a stable lithium metal anode. A new battery venture called Blue Current that I started with my co-inventor, Joe DeSimone and Alex Teran in 2014 hopes to take all-solid batteries to the next level. I will use my start-up experience to indicate what I think the roles of government labs, universities, and small businesses are in the emerging clean energy landscape. Deployment of clean energy on scale remains a daunting challenge; partnerships involving different segments of society are our best hope for addressing this challenge.
Leveraging Available Resources: A Small Business Perspective on Collaboration and Commercialization
Authors: Ayers Katherine E
Published: February 2020

In a small company working on electrochemical technologies, access to external resources (researchers, equipment, grants) can be a deciding factor in bridging from innovative concepts to demonstration and implementation. Often small companies need to hire more generalists than specialists, since employees need to be able to cover multiple roles, but the result is a reduced ability to analyze parameters in depth. Chararacterization equipment is also often limited. In addition, electrochemical technologies often take several years to get from proof of concept to product, due to the manufacturing complexities and safety requirements of electrodes. Strategies to stretch internal resources are therefore needed for success.

Proton OnSite has been highly effective in developing technology roadmaps, collaborations, and project portfolios that support our business and advance our core technologies, while providing opportunities for future growth. The company has also been successful in finding niche applications to drive product development at increasing scale, which spreads out the required investment in manufacturing. In this talk, Proton’s product evolution will be discussed, as well as external collaborations with national labs, universities, and other companies that have driven specific component advancements. Specific case studies will be discussed.

Another challenge in technology development is obtaining external support, within the constantly changing landscape of favored technologies and policies. A strategy that Proton has leveraged is to look for synergistic technologies that both expand our technology portfolio and can feed elements back to our core products. Examples of technologies which complement our core business in hydrogen generation from PEM electrolysis will also be discussed.
Development of Magnetic Films for Encoding of Information on Heavy Equipment Parts
Authors: Zhao Fu , Pechan Tom , Wilmeth Steve , Sechi Paolo , Arns Don , Zangari Giovanni
Published: February 2020

Ferromagnetic coatings with hard magnetic properties are widely used for long-term information storage. In the form of hard disk drives, these devices provide reliable storage for more than half the digital information produced worldwide. The same technology could however provide solutions for sensing with regard to location and motion in other technological contexts, for example excavation, mining and construction equipment.

A research and development project has been undertaken by a team including a non-profit, independent research center, a company manufacturing specialty tubing and bars, and a university laboratory, with the objective to develop an electroplating process to coat steel rods with a magnetic coating characterized by medium-high coercivity (few thousand Oe), high magnetic saturation (~ 1 T), suitable readback signal, and stable magnetic response during operation. In parallel, a device to write and read magnetization transitions on these coatings with sub-mm linear density was designed and developed. While the magnetic properties discussed above are relatively easy to achieve in an average environment, in an excavation and construction environment the coating will be subject to large mechanical stresses, large impact forces and friction, requiring unusual mechanical properties.

In this talk we will examine the material selection, the laboratory efforts to achieve the magnetic properties of interest at low cost, while providing the necessary mechanical strength, and we describe the scale-up process carried out at the company location. Results, competing technological approaches and lessons learned will be discussed in detail.
Analyzing the Prospects of Electroreduction of Carbon Dioxide to Value-Added Chemicals
Authors: Kenis Paul J.A.
Published: February 2020

Increasing evidence suggests that the unwanted effects of climate change, including global warming, rising sea levels, and erratic weather patterns are the result of the increasing concentration of carbon dioxide (CO2) and other greenhouse gasses in the atmosphere. Further development and integration of renewable but intermittent energy sources such as solar and wind, as well as enhancing energy efficiency in buildings and transportation applications will be critical to significantly reduce global CO2 emissions. An alternative strategy to reduce CO2 emissions is the capture and subsequent electrochemical reduction of CO2 into useful chemicals such as formic acid, carbon monoxide (CO), hydrocarbons, or alcohols. This approach has the additional advantage that it can enhance the utilization of renewable energy that is produced in excess of grid demand (too much solar or wind energy production) and currently wasted.

Multiple research efforts over the last decade have developed increasingly better cathode catalyst for the efficient electrochemical reduction of CO2 to formic acid, CO, and other products. At the same time progress has been made on anode catalysts (typically for the oxygen evolution reaction), gas diffusion electrodes suitable for CO2 electrolysis cells, and on the optimization of electrolysis operating conditions. Despite this progress, it is still unclear whether this emerging electrochemical technology has the potential to achieve a net reduction in CO2 emissions and is economically feasible.

We developed a gross-margin model for a first order estimate of the economic viability of CO2 electrolysis. Second, in a collaborative effort, we performed a techno-economic analysis of a process that starts with the flue gas from a 0.5 MW power plant, captures the CO2, converts that CO2 into CO, which then in combination with hydrogen from a water electrolyzer is converted into liquid fuels via the Fischer Tropsch process. The results of these models with respect to economic viability and their ability to reduce greenhouse gas emissions will be presented.
(Invited) Membrane Development for Energy Technologies
Authors: Soloveichik Grigorii L.
Published: February 2020

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including electrochemical energy storage and transformation for grid scale and automotive applications.

This presentation will highlight new technologies using ion-selective membranes for energy storage (batteries and flow batteries) and generation (fuel cells) including funded by ARPA-E. Several projects on development of anion-conducting membranes for CO2 reduction and water electrolysis are supported through OPEN program. The Reliable Electricity Based on Electrochemical Systems (REBELS) program is targeting distributed generation for more reliable and flexible smart grid focuses on intermediate temperature fuel cells that operate between 200-500oC. Two types of ionic conducting membranes (proton- and oxygen-conductors) are applied in such fuel cells. The Integration and Optimization of Novel Ionic Conducting Solids (IONICS) seeks to enable transformational electrochemical cells by creating novel solid ion conductors with wide range of desirable properties such as low ionic area-specific resistance, high chemical and electrochemical stability, high selectivity, good mechanical properties and to develop and apply methods for processing of solid ion conductors at a practical scale.

The presentation will highlight the use of various ion conducting membranes for separation processes including electrochemical pumps and in fuel cells and flow batteries. Compatibility of fuels, electrocatalysts and membranes will be discussed. State-of-the-art technologies for electrochemical synthesis of fuels and organic active materials using different types of electrochemical cells will be presented.
(Invited) Capturing and Converting CO2 with High Temperature Electrochemical Methods
Authors: Huang Kevin
Published: February 2020

Cost competitive and easily accessible fossil fuels are the dominant energy source powering our society. However, burning fossil fuels emits significant amount of CO2, a greenhouse gas that can cause global warming and climate change. Therefore, mitigating CO2 emissions from the use of fossil fuels is imperative. Among all the options, carbon capture and storage (CCS) is considered the best near-term solution. The CO2 capture technologies currently being developed are targeting three point sources related combustion and gasification processes: post-combustion, oxyfuel combustion and pre-combustion. The state-of-the-art CO2 capture methods are primarily based on reversible chemical/physical absorptions/ adsorptions principles. A grand challenge to these technologies is the high cost and energy penalty. Developing advanced cost-effective and energy-efficient carbon capture technologies is therefore highly desirable. In this presentation, we show by extensive experimental data and theoretical analysis that two classes of mixed ion and electron conductors are promising candidate membranes for high-flux, high-selectivity, cost-effective and energy-efficient carbon capture based on the electrochemical principles. By combining these membranes with proper conversion mechanisms, the captured CO2 can be instantly converted back to fuel form, making the overall process carbon neutral.
PBI-HFA Hollow Fiber Membrane for Selective Hydrogen Separation
Authors: Choi Sun Hee , Kim Do Young , Yoon Chang Won , Han Jonghee
Published: February 2020

We demonstrated for the development of PBI-HFA based asymmetric hollow fiber membrane for hydrogen separation. High molecular weight PBI-HFA was synthesized in-house by a solution polycondensation method [1]. Hollow fiber membranes were fabricated by conventional dry-jet wet spinning technique. Defect free asymmetric PBI-HFA hollow fiber membranes were successfully produced, which influenced of PBI-HFA concentration and LiCl as shown in Fig. 1. The effect of bore fluid chemistry was found to have a significant effect on the morphology as well as gas performance of the hollow fiber membranes. Development of PBI-HFA hollow fiber membranes with improved gas permeation properties their known excellent thermal and chemical properties depicts their potential for gas separation applications at harsh environment. As shown in Fig. 2, PBI-HFA hollow fiber showed good gas flux and selectivities for industrially important gas pairs such as H2/CO, H2/N2 with the ideal selectivities of 35.7 and 43.4, respectively, while the permeation fluxes of H2, N2, CO2 and CO were at 664, 15.3, 263.37 and 18.6 GPU at 1bar as given in Table. 1. Mixed gas results as given in Table. 2 discussed above indicate that PBI-HFA hollow fiber is an excellent H2 selective membrane material for syngas separations. This improvement in gas selectivities was attributed to their increased closer chain packing by high solubility.

Pressure
P (H2)
a

P(N2)
a

P(CO2)
a

P(CO)
a

1bar

664
15.3
263.37
18.6
43.4
2.52
35.70
17.21

2bar

1219
31.02
471.26
35.82
39.3
2.59
34.03
15.19

3bar

1783
46.61
691.78
54.13
38.25
2.58
32.94
14.84

4bar

2353
63.58
978.76
71.83
37.13
2.4
32.76
15.44

a Expressed as permeance in GPU (1 GPU = 1´10-6cm3(STP) cm-2s-1 cmHg-1).

Table 1. Gas separation performance of PDMS coated PBI hollow fiber at normalized temperature.

(H2)%
(N2)%
(CO2)%
(CO)%

Mixture gas composition

51.53
21.2
7.63
17.86

1
bar

89.6
0
3.05
0.33

2bar

84.19
0
2.49
7.99

3bar

65
3.7
6.49
23.5

Table 2. Mixture Gas separation performance of PDMS coated PBI hollow fiber membrane at 21℃, 100℃, and 200℃ temperature

[1] S. Kumbharkar, M. N. Islam, R. Potrekar, and U. Kharul, "Variation in acid moiety of polybenzimidazoles: investigation of physico-chemical properties towards their applicability as proton exchange and gas separation membrane materials," Polymer, vol. 50, pp. 1403-1413, 2009.

Figure 1
(Invited) Electrically Conductive Diamond Membrane for Electrochemical Separation Processes
Authors: Gao Fang , Nebel Christoph E.
Published: February 2020

Boron-doped diamond has been applied as an outstanding electrode material for electrochemical applications. Using templated growth techniques, a variety of diamond nanostructures like diamond wires and diamond foams can be fabricated [1, 2]. Using quartz or glass fiber paper as growth templates, porous diamond membranes are fabricated [3]. Compared to polymer membranes or membranes based on sp2 carbons, diamond membranes can survive in aggressive media and high temperature conditions. Also, the ion selectivity can be controlled by surface terminations as well as the bias potential of the membrane. Therefore, this kind of membranes is very promising for the electrochemical separation processes such as desalination, pollutants concentration and protein separation. However, both the fabrication and application of diamond membranes are so far reported only in very limited cases.

In this paper, we report our recent progress with respect to the templated diamond growth using quartz fiber paper as the growth template [3]. With optimized microwave CVD growth, nanocrystalline diamond film is fully coated onto the quartz fiber as has been confirmed via SEM. The growth conditions in terms of temperature, methane concentration and boron/carbon ratio are investigated in detail. The diamond quality is evaluated via Raman spectroscopy. The potential window of the diamond membrane is determined via cyclic voltammetry in an aqueous NaClO4 solution to be over 3 V. By applying potential to the membrane, reactive ions will accumulate inside the membrane and change its porosity. As a result, the ion flux through the membrane can be well tuned. This ion selectivity can be used to separate charged molecules. As a proof of concept, Rhodamine B, Ni2+ and Cu2+ are separated by the diamond membrane under different biases. Finally, due to the robustness of diamond, the membrane can be cleaned via a high potential (+2 V vs Ag/AgCl) oxidation process in situ. Metal deposits and organic contaminants are proved to be removable by this method. Therefore, this membrane is also suitable for applications where only simple in-situ maintenances are possible.

This project has received funding from the European Union's Horizon 2020 Programme under Grant Agreement no. 665085 (DIACAT).

[1] Gao F, Wolfer MT, Nebel CE. Highly porous diamond foam as a thin-film micro-supercapacitor material. Carbon. 2014;80(0):833-40.

[2] Gao F, Lewes-Malandrakis G, Wolfer MT, Muller-Sebert W, Gentile P, Aradilla D, et al. Diamond-coated silicon wires for supercapacitor applications in ionic liquids. Diamond Relat Mater. 2015;51:1-6.

[3] Gao F, Nebel CE. Diamond-Based Supercapacitors: Realization and Properties. ACS Appl Mater Interfaces. 2015.
(Invited) Characterization of Semiconductor Materials Using Syncrotron Radiation, XAFS and X-Ray CTR Scattering
Authors: Tabuchi Masao
Published: February 2020

Synchrotron radiation (SR) is a very powerful tool for the material science. However some of the characterization techniques using the SR are not so popular for the researchers studying on the semiconductors. At the PRiME 2016 meeting, I would like to provide three topics relating to the SR. Two of them are topics on the measurement techniques, which must be interesting for the researchers of semiconductors. The third one is to introduce a compact SR facility recently built in Japan, which is successfully operating for the academic and industrial researchers.

X-ray absorption fine structure (XAFS) measurement might be one of the minor techniques for the researchers studying on semiconductors, although it is a very powerful technique to investigate atomic scale structure. For example, by the XAFS measurement, a local structure around a target element in a semiconductor crystal can be revealed. In other words, if impurity atoms in a crystal locate at interstitial site or are substituting matrix can be discussed and the distortion of the lattice around the impurity atoms can also be estimated. Further, if the impurity atoms are ionized or not, is able to be determined by the XAFS measurement. Because the XAFS measurement is a kind of absorption measurement in the energy range of X-ray, the SR is essentially important to scan the energy of the incident X-ray and it is very difficult to conduct the measurement at laboratory using ordinal X-ray sources like X-ray tubes. That might be one of the reasons why the XAFS measurement is not so popular. At the PRiME 2016 meeting, I would like to introduce what the XAFS measurement is, why we can obtain such atomic scale information from the spectra, and for what kind of studies the measurement is useful.

X-ray CTR scattering measurement is an important technique to study on layer structures like semiconductor films so precisely in an atomic scale and it is another measurement which essentially needs the SR. In order to measure the so week CTR scattering signal, the intensity of the SR is very important. When the measurement is conducted properly and obtained spectra are analyzed carefully, the results show us the interface structures of semiconductor hetero layers in an atomic scale. I would like to show some of the examples at the meeting.

Finally, I am going to introduce a recently built compact SR facility in Aichi, Japan. The facility is named Aichi SR, of which acceleration energy and current are 1.2 GeV and 300mA. By using super conducting bending magnets of 5 T as light source, the facility can provide X-rays in the energy range of hard X-ray, more than 5 keV and up to 20 keV or higher as easy as those in the range of soft X-ray. The specs of the light source are not on cutting edge, however, the general design is so useful and stable for the users who would like to use the SR as a daily tool to characterize their samples. Such a facility must be very important to bottom up the level of the researches.
Development of Silicon Substrate for Advanced Multi-Chip Packaging Process with the Enhanced Gettering Ability
Authors: An Jeong-Hoon , Kim Jang-Seop , Lee Anselmo Jaehyeong , Park Hyung-Kook , Park Hyeung-il , Moon Byeong-Sam , Lee Sang- Hyun , Park Jea-Gun
Published: February 2020

Gettering techniques are the key features in recent semiconductor industry to develop the high performance devices. Above all, the intrinsic gettering is considered as the easiest way to achieve metal gettering effect in a silicon substrate with the formation of extended defects during thermal process. Moreover, intrinsic gettering is the only way available in the multi-chip packaging (MCP) technique that cannot be accompanied by the extrinsic gettering due to the backside grinding process [1]. Therefore, the epitaxial wafers based on the heavily boron-doped substrate have been used in MCP to obtain the gettering effect even in thinned substrate. However, the use of epitaxial wafers in the fabrication process leads the high cost of ownership (CoO) in the production. Thus, various investigations on the substitution of the epitaxial wafer have been carried out to reduce the total process cost.

In this work, a novel concept of silicon substrate that represents the low-cost and comparable gettering efficiency on metal contamination to that of the epitaxial wafer was proposed. To achieve these features, rapid thermal annealing (RTA) adjusted at high temperature was applied to the base wafer with high interstitial oxygen (Oi) concentration. As shown in Fig. 1
a), oxygen precipitates was evenly formed over the entire bulk in the RTA-treated high Oi wafer after device heat simulation, which is favorable in thinned substrate for the MCP. In addition, the average size of oxygen precipitates increased in high Oi wafer, which means the ‘total inner surface’ of oxygen precipitates [2] was possibly expanded over the threshold value required for effective gettering. Finally, we confirmed the effect of RTA-treated high Oi wafer on the metal gettering after the thinning process, especially in nickel, which was more effective than in the epitaxial wafer up to 1.5 times while the gettering ability for copper was almost saturated in all wafer condition, as shown in Fig. 1 b). Specific features of our results will be discussed in detail.

Fig. 1 a) Optical micrographs of entire bulk observed in RTA-treated wafers with different Oi level. Wafers were heat-treated and etched in the Wright etchant for 5 min. b) Gettering ability for copper and nickel contamination measured in RTA-treated samples after thinned to 30 μm thickness.

References

[1] J. H. An, J. S. Kim, J. Y. Kim, K. S. Lee, H. B. Kang, B. S. Moon, S. H. Lee, Y. Shin, S. M. Hwang, and H. Y. Park, ECS Transactions
50(5), 319 (2012).

[2] R. Hoelzl, M. Blietz, L. Fabry, and R. Schmolke, The Electrochem. Soc.
PV
2002-2, 608 (2002).

Figure 1
(Invited) Modeling Extended Defects in Semiconductor Devices
Authors: Moroz Victor , Wong Hiu Yung , Choi Munkang
Published: February 2020

We perform analysis of several key aspects of the extended defect formation and their impact on silicon and GaN transistors. Heterogeneous epitaxy has been an enabling technique in transistor design since 90 nm technology node. The most widely used stress engineering technique is based on introducing crystal lattice mismatch stress by growing SiGe on Si. Depending on Ge content and on the size and shape of the selectively grown SiGe islands, the lattice mismatch stress can be high enough to introduce edge dislocations and stacking faults. Once the dislocations are created, they can move, driven by stress gradients towards more energetically favorable locations. An example of creating geometrical features to attract dislocations towards certain area has been demonstrated experimentally for epitaxial SiGe layers exceeding critical thickness on non-planar Si surfaces [1]. We reproduce such behavior by numerical minimization of elastic strain energy of an ensemble of {111} stacking faults (Fig. 1).

Whenever dislocations manage to escape such herding and encroach into sensitive transistor areas, we perform quantum transport analysis to estimate the impact of a dislocation on electron scattering, on-state and off-state currents for Si nanowires with 5nm design rules.

Another area where extended defect monitoring is essential is the GaN power switches. To achieve low buffer leakage in AlGaN/GaN HEMT for high voltage applications, it has been proposed to intentionally dope the GaN buffer with carbon [2]. This creates acceptor traps in the buffer to pin the Fermi Level at ~0.86 eV above the valence band [3]. A p-type buffer is thus formed and isolated from the Two-Dimensional Electron Gas (2DEG), which aggravates current collapse [3][4]. However, experimental results show that the magnitude of current collapse is less than suggested by modeling which can be attributed to the buffer being connected to the 2DEG through threading dislocations [3]. In this work, we perform 3D TCAD analysis of the impact of threading dislocations on the buffer trapping/de-trapping and current collapse.

[1] R. Gatti, F. Boioli, M. Grydlik, M. Brehm, H. Groiss et al., Appl. Phys. Lett., 98, 121908 (2011)

[2] E. Bahat-Treidel, F. Brunner, O. Hilt et al., IEEE Trans. Electron Devices, 57(11), 3050–3058 (2010)

[3] M. J. Uren, M. Silvestri, M. Cäsar, G. A. M. Hurkx, J. A. Croon, J. Šonský, and M. Kuball, IEEE Electron Device Lett.
35(3), 327–329 (2014)

[4] M. J. Uren, J. Möreke, and M. Kuball, IEEE Trans. Electron Devices
59 (12), 3327–3333 (2012)

Fig. 1. Dislocations in epitaxial SiGe layer move towards the bottom of a V-shaped trench in Si wafer (a). Each additional dislocation reduces the total elastic strain energy of the structure (b).

Figure 1
(Invited) Mobile Ions, Transport and Redox Processes in Memristive Devices
Authors: Valov Ilia , Luebben Michael , Wedig Anja , Waser Rainer
Published: February 2020

Redox-based resistive switching memories (ReRAM) developed rapidly in the last decade as most promising candidates for nanolelectronic industry for new type non-volatile memory devices fulfilling the demands for green IT i.e. low power consumption, high operation speed and integration density, scalability and reliability. Recent achievements have clearly demonstrated the diversity of applications these devices can be used apart from the simple memory function – for neuromorphic applications, alternative computing and logic operations, selector elements. These developments are supported by system functionalities having their origin in the electrochemical nature of the ReRAM cells.

In this talk the newest achievements in the microscopic understandings of the processes responsible for the ReRAM functionalities will be presented. It will be shown that different ions (both cations and anions) are mobile and can undergo electrochemical transformation and thus, contribute to the resistive switching. The effects of moisture will be presented and their importance for both ECM and VCM ReRAMs will be discussed. The influence of different electrode materials in terms of electrocatalytic activity and passivation behavior will be highlighted. Finally it will be shown that the nanobattery effect is fundamental and inevitable for the neuromorphic applications.
High-Performance Thin-Film Transistors Based on Highly Crystalline CVD-Grown Multilayer MoSe2 Films
Authors: Liu Na , Jung Chulseung , Moon Hyunseong , Hong Seongin , Hong Young Ki , Omkaram Inturu , Kim Sunkook
Published: February 2020

Layered semiconductors based on transition metal dichalcogenides (TMDs) (MX2, M = Mo, W; X = S, Se, Te) exhibit many distinctive characteristics, including wide band gap (Eg > 1 eV), high carrier mobility (>100 cm2/VS), large photoresponsivity (~500 A/W), and an outstanding mechanical flexibility. Thus, the TMD materials can serve as high-performance flexible/stretchable multifunctional electronics such as field-effect transistors (FETs), photodetectors, sensors and integrated circuitries. For realizing such electronic devices, reproducible large-area production of two-dimensional TMD materials becomes a key issue.

It has been reported that MoSe2 shows a higher photoresponsivity compared to MoS2 because of the quantum confinement effect during the bad gap transition. On the other hand, multilayer TMDs provide a wider spectral response and higher photoresponsivity than monolayer TMDs. Additionally, FETs based on multilayer TMDs offer a relatively high performance, which are expected to be more suitable for commercial fabrication process than monolayer TMDs. Several groups have successfully synthesized monolayer MoSe2. However, there is hardly to find any research in chemical vapor deposition (CVD)-grown multilayer MoSe2 and its applications.

In this study, a highly crystalline multilayer MoSe2 film was grown by CVD method directly onto SiO2 substrates. Firstly, we used a relatively high pressure (>760 Torr) to form multiple nuclei during the CVD growth, resulting in multilayer MoSe2 film. The fabricated multilayer MoSe2 thin-film transistors (TFTs) exhibit ambipolar behaviors with reasonably large field-effect mobility (~10 cm2/Vs) and high photoresponsivity (93.7 A/W). Secondly, large-grain multilayer MoSe2 was synthesized using a modified CVD method. Polycrystalline compounds of MoSe2 as precursor were directly vaporized onto Mo-coated SiO2 substrates. The multilayer MoSe2 has a relatively large grain size of several hundred micrometers. Transistors based on such MoSe2 single grains show n-type characteristics with field-effect mobility up to 121 cm2/Vs and on/off current ratio higher than 104 on Si wafers or plastic polyimide films. The MoSe2 transistor on polyimide substrate even shows good mechanical flexibility while bending down to a radius of curvature as small as 5 mm. The overall results of CVD-grown multilayer MoSe2 offers high speed, highly photoresponsive transistor for high-performance flexible/stretchable electronics.
Multiple Magnetic Resonance of Nuclei in a Two-Dimensional Electron System
Authors: Qian Xuan , Ji Yang , Umansky Vladimir
Published: February 2020

Nuclear magnetic resonance (NMR) with high sensitivity is a powerful tool to study nuclear spin physics in semiconductors. Recent progress in quantum information processing requires deep understanding of nuclear spins, which are almost ideal qubits for the manipulation and storage of the quantum information [1].Optical pumping can increase the polarization of nuclear spins in semiconductors such as GaAs by many orders of magnitude, improving the sensitivity in conventionally detected nuclear magnetic resonance experiments. Optical detection of these NMR transitions may further increase the sensitivity, allowing an all-optical NMR which is free of radio frequency fields.

    Here we report all-optical NMR experiments in a GaAs/AlGaAs two-dimensional electron system. When the modulation frequency hits the frequency of a transition between nuclear levels of the different isotopes, a resonance appears in the Kerr rotation signal. Besides the fundamental resonance for frequency matching also resonances at frequencies at fractions of the fundamental frequency occur, in good accord with a simple model. Such multiple NMRs arise from interaction between modulated spins of polarized electrons and nuclear spins[2].

References

[1] D. D. Awschalom, D. Loss, and N. Samarth, Semiconductor Spintronics and Quantum Computation (Springer-Verlag, Berlin, 2002)

[2] X. Qian, et al., Phys. Rev B 93, 035302 (2016).
Microstructural Dependence of Performance in Potentiostatically Electrodeposited Soft Gold Coatings
Authors: Banga Dhego
Published: February 2020

The control and stability of microstructure in electrodeposited metals is critical to the performance and reliability of many technologies including electrical contacts, tribological coatings, and low-emissivity surfaces. At present, however, the relationships between growth conditions and microstructural development are understood primarily at a phenomenological level, limiting the ability to predictively engineer these materials. In this study, we tacked a subset of this long-term, foundational problem through an experimental investigation of the elementary mechanisms governing grain evolution in electrodeposited soft Au coatings. We focused on grain structure because of its ubiquitous importance to the properties of electrodeposited materials, including emissivity, contact resistance, electrical conductivity, mechanical strength, crystal structure, and surface and bulk morphologies. Our experiments, which employed state-of-the-art surface and bulk microscopies, quantitatively linked the growth conditions to the surface morphology dynamics, subsurface grain structure, and resulting films' properties.
(Invited) Ferroelectric (Hf,Zr)O2 Films
Authors: Hwang C. S.
Published: February 2020

Since the first report on the ferroelectricity in ultra-thin Si-doped HfO2 film [1], the unexpected ferroelectricity in doped HfO2 and (Hf,Zr)O2 solid solution films are attracting a great deal of attention from the ferroelectric community.[2] Compared to the conventional ferroelectrics based on perovskite structure, HfO2-based ferroelectrics can be extremely thin with mature deposition process such as atomic layer deposition, environmentally benign with lead-free nature, and Si-compatible.[2] Especially, the ferroelectricity and antiferroelectricity in (Hf,Zr)O2 solid solution are considered highly promising for various electronic and energy applications.[2] The ferroelectric Hf0.5Zr0.5O2 film could have remanent polarization value higher than 20 mC/cm2, and could endure more than 109 times of electric field cycling, meaning that it is a promising candidate for the future memory applications.[2] The high coercive field of ~1 MV/cm enables even 10 nm-thick films can have sufficiently large memory window.[2] The antiferroelectric Hf0.2Zr0.8O2 film could harvest 11.5 J/cm3 cycle from its pyroelectricity, and could show adiabatic temperature change of 13.4 K for solid state cooling.[3] As a electrostatic capacitor, Hf0.3Zr0.7O2 film could store 46 J/cm3 of electric energy.[4] On the other hand, the academic researches to understand this unexpected ferroelectricity is also under rapid progress. The two step polarization switching based on the involvement of intermediate nonpolar phase in Hf0.4Zr0.6O2 film was also reported, which could be understood based on the classical first order phase transition theory.[5] The so-called “wake-up” effect, which generally means the depinching of the pinched ferroelectric hysteresis in pristine state in (Hf,Zr)O2 film, is another interesting topic in this field. The wake-up effect is now ascribed to the involvement of the complicated polymorphisms in (Hf,Zr)O2 films being related with the motion of charged defects such as oxygen vacancies.[6] In this talk, the recent progresses in the ferroelectric performance of (Hf,Zr)O2 thin films will be comprehensively reviewed based on both theoretical and experimental studies.

[1] T. S. Boescke et al., Appl. Phys. Lett. 99, 102903 (2011).

[2] M. H. Park et al., Adv. Mater. 27, 1811 (2015).

[3] M. H. Park et al., Nano Energy 12, 131 (2015).

[4] M. H. Park et al., Adv. Energy Mater. 4, 1400610 (2014).

[5] M. H. Park and H. J. Kim et al., Nanoscale, DOI: 10.1039/c5nr08346j

[6] H. J. Kim et al., Nanoscale 8, 1383 (2016).
(Invited) Advanced ALD Reactor Designs
Authors: Marcus Steven Darrell , Mack Jerry , Vats Vinayak , Okuyama Yoshi , Nie Ben , Yang Lin , Song Kay , Kim Gi , Nag Somnath , Kim Eungsoo , Karim Zia
Published: February 2020

There are many different ALD reactor designs and configurations supporting the semiconductor industry. These designs include temporal and spatial pulse/purge separation, thermal versus plasma enhanced, and single wafer versus batch reactor designs. Gas and precursor delivery designs are varied as well including cross flow versus showerhead, solid source versus liquid source, vapor draw/bubbling versus injector/vaporizer. These designs were developed based on meeting a particular film or application or process and film metric requirement (step coverage, throughput, particle performance, etc.).

 

The intent of this paper is to review, compare and contrast these designs and applications relative to different design combinations. The data presented will be from our AIXTRON high performance mini-batch QXP-8300. This tool is configured with a showerhead integrated with a vaporizer delivery system specifically designed for low vapor pressure precursors. A typical temporal design, QXP-8300 is a multi-wafer ALD system with a small volume confined process space. We will also be citing examples in the literature on spatial and other temporal thermal and plasma ALD configurations. An analysis of film performance and CoO comparison will also be presented.
(Invited) Using Inherent Substrate-Dependent Nucleation to Promote Metal and Metal Oxide Selective-Area Atomic Layer Deposition
Authors: Parsons Gregory N. , Kalanyan Berç , Atanasov Sarah E. , Lemaire Paul , Oldham Chris
Published: February 2020

Substrate-dependent nucleation during CVD has been heavily studied, and several strategies for selective growth are known. Compared to CVD, atomic layer deposition generally allows more precise control over surface reactions, but to date, the most successful selective-area deposition processes are based on CVD and not ALD mechanisms.

Most ALD processes have an inherent substrate bias during nucleation, leading to problems in process development. Better understanding of this native substrate bias can be used to promote and enhance selective-area ALD. We have studied nucleation of ALD metals and dielectrics to promote native substrate bias and improve selectivity. Tungsten ALD using WF6/SiH4 onto SiO2 proceeds when surface Si-H (from SiH4) begins to form, allowing WF6 reduction to W and elimination of SiF4. We hypothesized that the introduction of a H2 or H-plasma exposure into the ALD sequence may help remove Si from the SiO2, which could extend the nucleation delay on SiO2, while not affecting W growth on Si. Using ellipsometry, XPS, high resolution SEM and in-situ quadrupole mass spectrometry we find that a H2 exposure during W ALD on ex-situ prepared SiO2 decreased the rate of W nucleation compared to growth without the H2 step, effectively increasing the selectivity window. 

Also, using XPS in-situ FTIR, we explored how various oxide ALD precursors react with different surfaces. For example, doing TiO2 ALD using TiCl4 with titanium isopropoxide as the oxygen source (instead of water), we find that eliminating water slows the substrate oxidation in areas where TiO2 deposition is not desired, thereby promoting the nucleation delay to as much as 200 ALD cycles at 170°C, resulting in a maximum selectivity thickness, ts,max
≈ 2–3 nm. We will discuss other details of initial reactions obtained from in–situ infrared spectroscopy, quartz crystal microbalance, TEM, SEM, ellipsometry and other tools to better understand and improve “inherent” substrate selective ALD of metals and metal oxides.
Fabrication of p-Type La: Fe2O3 as Photocathode Via Atomic Layer Deposition
Authors: Peng Qi , Du Chun , Wen Yanwei , Shan Bin , Chen Rong
Published: February 2020

Solar water splitting is a promising approach to develop the renewable energy. [1] Due to the excellent solution stability, earth abundance and suitable band gap, hematite is one of the most promising photoanode with n-type characteristics. [2] Nevertheless the high carrier recombination, [3] slow reaction kinetics [4] and mismatch of the band edge with the water splitting potentials [5] suppress the further promotion of its photolelectrochemical (PEC) performance. Combining with p-type material is an efficient way to tune the band structure and improve the charge carrier separation of hematite. Mg doped-hematite film with p-type characteristics was fabricated by atomic layer deposition (ALD) and significantly reduced the onset potential for photocurrent. [6] Recently, the perovskite LaFeO3 with band gap of 2.07eV are fabricated with intrinsic p-type characteristics and exhibit a high hydrogen evolution rate under visible light. [7, 8]

Here we report the fabrication of p-type La: Fe2O3 and the n-p junction of Fe2O3/La: Fe2O3 by ALD technique for its excellent conformability and controllable film growth with low defect densities. We will demonstrate the La: Fe2O3 film with p-type characteristics with Mott−Schottky plots and Hall Effect. The cathodic photocurrent as well as the PEC performance will also be discussed. By preparing the n-p junction of Fe2O3/La: Fe2O3, we design to reduce the onset potential for the photocurrent more than 100 mV comparing to the pure Fe2O3 photoanode. The incident photon-to-current conversion efficiency (IPCE) of Fe2O3/La: Fe2O3
n-p junction can be increased more than 10% at 400 nm. The PEC performance, and its mechanism will also be discussed.

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K. J McDonald, K. S. Choi, Chem. Mater., 23, 1686 (2011).

J. Brillet, M. Cornuz, F. L. Formal, J. H Yum, M. Grätzel, K. Sivula, J. Mater. Res., 25, 17 (2010).

Y. Lin, Y. Xu, M. T. Mayer, Z. I. Simpson, G. McMahon, S. Zhou , D. Wang, J. Am. Chem. Soc., 134, 5508 (2012).

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Q. Peng, J. Wang, Y. W. Wen, B. Shan, R. Chen, RSC Adv., 6, 26192 (2016).
(Invited) Atomic Layer Deposition of Multiferroic Materials
Authors: Chang Jeffery , Pham Calvin D , Chang Jane P.
Published: February 2020

The introduction of novel and functionally improved materials into silicon based integrated circuits is a major driver to enable the continued down-scaling of circuit density and performance enhancement in analog, logic, memory and sensing devices. Many novel materials, such as multiferroics, magnetic materials and phase change materials, are introducing new and unique functionalities that can enable continued technological advancement. The demand of engineering and precision control of these multi-functional materials such as multiferroics and their interfaces at an atomic level has grown immensely due to their versatile applications. Leveraging the self-limiting surface reactions in atomic layer deposition process, complex materials can be synthesized not only with elemental precision to achieve the desired functionality but also with outstanding conformality to ensure superior interface coupling. The latter enables the integration of ferroelectrics with ferromagnetics to realize multiferroism and magnetoelectric effect. In this talk, I will discuss current research advances in atomic layer deposition for synthesizing multifunction and complex metal oxides with tailored electronic, chemical, interfacial, thermal properties and microstructures. Specifically, I will highlight our most recent research on the engineering of multi-ferroic materials for applications in memory, antenna and motors.