bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Contacts in Advanced CMOS: History and Emerging Challenges
Authors: Lavoie Christian , Adusumilli Praneet , Carr Adra V , Jordan Sweet Jean S. , Ozcan Ahmet S , Levrau Elisabeth , Breil Nicolas , Alptekin Emre
Published: February 2020

With the continued evolution of CMOS technologies, which includes recent changes in both device geometries and contact schemes, contact lengths of advanced devices are now reaching below 20 nm. At these dimensions, material microstructure (grain size) becomes similar to contact size and interface quality becomes critical to device performance. The sustained reduction in contact size together with the complications associated with the introduction of non-planar devices have recently lead to drastic modifications in process flow for the contacts. These new process schemes have altered the materials requirements for the contacts to the point where two factors dominate material selection: a low intrinsic contact resistivity interface and a higher morphological stability. As a result, advanced CMOS development has unexpectedly made a return to contacts based on titanium. In this presentation, we will first describe the evolution of materials used for contacts through the scaling of CMOS technologies. We will discuss what is observed in the titanium thin films when annealed under various advanced treatments as the metal film thickness is reduced below 10 nm.
Study of Seed-Layer Stability on Copper Electrolytic Bath
Authors: Delbos Elise , Setoain Imanol , Frégnaux Mathieu , Gonçalves Anne-Marie , Etcheberry Arnaud
Published: February 2020

For years, the effectiveness of the Damascene process has allowed the semiconductor industry to successfully keep the pace with the aggressive scaling of Moore’s law. However, ever increasing costs have raised the need for alternative technologies bringing advantages in terms of performance gain, time to market and cost competitiveness. Thus, 3D chip stacking technologies have now become a field of extensive research [1-2]. The today improvements are mainly devoted on the current process optimization or the development of new methods to elaborate barriers, seed-layers and fillings compatible with technological advances and the more and more aggressive via aspect-ratio [3]. Generally made in copper by CVD, PVD, ALD or electrografted technics, the seed-layer plays an important role during the via filling. Its principal criteria are to be uniform in term of thickness and continuous to ensure a good electrical contact during the electrochemical process [4]. During the filling process, the wafers and thus the seed-layer are first pre-wetted using DI water or etching solutions and then immerged in the copper bath. Traditionally an idle time is maintain before applying the current density, to favour the species exchange.

However, few studies have an interest for the reaction during this idle time and in more general consideration for the copper seed-layer stability on the copper electrolytic bath. Hence, the copper seed-layer is dissolved in the plating bath due to electrochemical reaction with the oxygen dissolved in the bath [5-7]. In this research work, the stability of the seed-layer and its dissolution rate are studied combining in-situ and ex-situ technics (figure 1). Open circuit potential versus time is an interesting approach for this study, allowing direct information on the surface modification during the idle time. Quartz microbalance measurements complete the analyses, giving direct information of weigh lost resulting from dissolution. As ex-situ characterization technics, SEM-EDS, XPS and RBS measurement were performed to characterize the surface states and the chemical composition after the idle time. Several parameters are particularly highlighted as the bath composition and its concentration and the rotation rate of the substrate.

[1] T.P. Moffat, D. Wheeler et al., IBM J. Res. Dev., 49, 19 (2005)

[2] P.M. Vereecken, R.A. Binstead, H. Deligianni, P.C. Andricacos, IBM J. Res. Dev, 49, 3 (2005)

[3] M. Datta, Electrochemical processing technologies and their impact in microelectronic packaging in Microelectronic Packaging, edited by M. Datta, T. Osaka and J.W. Schultze, CRC Press edition (2005)

[4] Part II Chip metallization in Microelectronic Packaging, edited by M. Datta, T. Osaka and J.W. Schultze, CRC Press edition (2005)

[5] R. Schumacher et al, J. Electroanal. Chem. 219 (1987) 311-3174

[6] K.Y. Electrochimica Acta, 38, 14 (1993) 2121-2127

[7] A.G. Zelinsky et al, Corrosion Science 46 (2004) 1083–1093

Figure 1
(Invited) 2D/3D Tunnel-FET: Toward Green Transistors and Sensors
Authors: Cao W. , Kang J , Banerjee Kaustav
Published: February 2020

MOSFETs have been the workhorse of the worldwide semiconductor industry and the primary building blocks of most electronic products of everyday use since the 1970’s. However, continuous miniaturization of MOSFETs, well beyond 100 nanometers, to sustain the ever growing need for increased transistor densities has given rise to a daunting power dissipation challenge during the past decade due to increasing leakage power arising from a fundamental limitation of their turn-on characteristics. This talk will examine the genesis of this challenge, and provide an overview of our recently demonstrated atomically-thin 2D layered semiconducting channel tunnel-FET (Nature 2015) that overcomes this challenge and is a new class of transistors in which electrons move in an extremely thin interface layer between a conventional 3D semiconductor (Germanium, as the source) and a thin film of atomically layered barrier material (molybdenum disulphide or MoS2, as the channel). The materials allow the electrons that carry the signal current to be injected through quantum mechanical band-to-band tunneling.

At present, our 2D/3D heterostructure TFET is the thinnest-channel subthermionic transistor ever made and exhibits unprecedented low leakage currents, high ON/OFF ratio, 2X higher ON current (w.r.t other experimental TFETs at 0.1 V), very low average subthreshold swing (SS) over four decades of drain current, and lowers power dissipation by over 90% compared to the state-of-the-art MOSFETs. Rigorous analysis of the physics of band-tails in 2D semiconductors and their various heterostructures, accomplished in our group (IEDM 2016), support the experimentally demonstrated minimum SS values. Moreover, we have also shown that 2D-material (such as MoS2) based conventional FETs provide an excellent platform for biosensing (ACS Nano 2014). Hence, 2D-TFETs that combine the advantages of an atomically-thin channel and the unprecedented sensitivity of a tunnel-FET (APL 2012), owing to their steep turn-on characteristics, can be employed for building a revolutionary new class of ultra-low power bio/gas sensors (Physics Today, Sept 2016).
The Virtual Diode with Electrostatic Doping
Authors: Lee K. , Bawedin Maryline , Parihar M. , Park H.-J. , Cristoloveanu Sorin
Published: February 2020

The ‘electrostatic’ doping is a fascinating feature of FD-SOI technology. In an ultrathin SOI device, the electron population induced by a positive gate bias spreads into the entire body (volume inversion or accumulation). The body behaves as an N-doped region albeit it was originally undoped. Reciprocally, negative gate bias turns the body into a P-type region. Such doping metamorphosis has been used for conceiving novel devices containing reconfigurable P-N junctions.

We investigate the virtual P-N junction constructed with electrostatic doping. The primary question is whether and to what extent it behaves as a regular diode with physical doping. Our test devices are PIN diodes with large gate underlap. The doping in the gated and ungated regions is induced by the bias on the front gate and on the back gate (ground plane), such as to emulate a fictive junction at mid-distance from anode to cathode. The devices have been processed with 28nm FDSOI technology including HKMG gate stack, 7 nm SOI film and 25 nm thick BOX.

The experimental I‒V curves look familiar to a diode but without complying with the conventional theory. First, the doping level is adjustable by the gates in a wide range, which offers the possibility to modulate the leakage current and the breakdown voltage. Second, the junction depletion region is no longer defined by the lateral field because the gate action leads to a 2D effect documented by simulations. Third, the virtual doping varies dynamically with the anode/cathode voltage. Finally, the junction position can be selected by appropriate gate biasing from the mid-body to the physical junctions. We show that this intriguing diode is very versatile and enables various applications. In particular, a unique characterization technique for carrier lifetime extraction in ultrathin films will be presented.
Reliability Characteristics of Low Dielectric Constant Materials Under Mechanical-Electrical Stress
Authors: Lee Chih-Yen , Cheng Yi-Lung , Haung Chiao-Wei , Chuang Yao-Cia
Published: February 2020

Electrical and reliability characteristics of dielectric materials are commonly studied under electric fields without considering mechanical stress effect. Electrical and reliability characteristics of silicon dioxide (SiO2) and porous low-k dielectric (p-low-k) films under mechanical-electrical compounded field effect using metal-insulator-semiconductor (MIS) structures were compared in this study. Under mechanical stress in both tension and compression, the increased capacitance and leakage current, and the reduced breakdown field were observed for both SiO2 and p-low-k films. P-low-k films displayed a larger degradation under mechanical stress. After mechanical unloading, electrical properties and reliability cannot be recovered. Additionally, the tensile and compressive stresses caused a similar degrading effect on a p-low-k film. In case of SiO2 films, a larger degradation was detected under compressive stress. This investigation demonstrates mechanical stress can influence the electrical characteristics and reliability of dielectric and are needed to pay more attention in this topic.
(Invited) The III-Nitrides as a Universal Compound Semiconductor Material: A Review
Authors: Zhou Chuanle , Ghods Amirhossein , Saravade Vishal G. , Patel Paresh V. , Yunghans Kelcy L. , Ferguson Cameron , Feng Yining , Jiang Xiaodong , Kucukgok Bahadir , Lu Na (Luna) , Ferguson Ian
Published: February 2020

The development of wide-band gap compound semiconductors materials and structures led by III-Nitrides (GaN, InN, etc.) have fueled a revolution of LEDs for lighting applications. However, these materials and related devices have also made contributions in the area of high power electronics, detectors, solar cells, spintronics and, more recently, thermal neutron detection and thermoelectric applications. This presentation will show how III-Nitrides could be considered an universal compound semiconductor material that may be able to replace the traditional III-V materials in many applications.
Recovery of Bias-Stress Ionized Igzo/SiO2 Interface States Via Cryogenic Relaxation
Authors: Mudgal Tarun , Bharadwaj Anish , Ganesh Prashant , Powell Eli , Manley Robert G. , Hirschman Karl D
Published: February 2020

Indium gallium zinc oxide (IGZO) has been considered a potential replacement for hydrogenated amorphous silicon in TFT applications due to process compatibility and an order of magnitude improvement in electron channel mobility. However the mechanisms responsible for instability under bias-stress remain an active research topic. Silicon dioxide serving as the gate dielectric and back-channel passivation layer in bottom-gate IGZO TFTs results in high quality interfaces. Applied bias-stress conditions demonstrate a voltage shift that can be attributed to ionization and/or alteration of oxygen-related defects at these IGZO/SiO2interfaces.

Bottom-gate IGZO TFTs with SiO2 gate dielectric and passivation layers were fabricated and tested under rigorous positive bias-stress (PBS) and negative bias-stress (NBS) conditions. The devices demonstrate good stability under PBS (t > 104 s), with minor distortion in the subthreshold region and a slight characteristic left-shift from an initial pre-stress state. This PBS-shift is attributed to a change in the energy distribution of defect states at the front-channel interface. During NBS the devices exhibited a significant left-shift (ΔV ~ 1-2 V), which is attributed to the transformation of neutral oxygen vacancies to ionized donor states at the back-channel interface. This transformation appears to improve the electrical homogeneity of the back-channel interface, inferred by a suppression of DIBL-like behavior. The NBS-shift was found to be reversible over long recovery times at room temperature. The recovery time was dramatically reduced when samples were subjected to cryogenic temperature (77 K), which represents an accelerated return to the pre-stress condition. TCAD simulation provides additional support to the interpretation of bias-induced stress on IGZO TFTs.
(Invited) High-Mobility Complex Oxide Films By MBE
Authors: Stemmer Susanne , Raghavan Santosh , Schumann Timo , Shoron Omor
Published: February 2020

Functional perovskite oxides may enable entirely new electronic device concepts, ranging from negative capacitance to charge amplification in phase change devices. A major challenge is the intrinsically poor charge carrier mobility of most perovskite oxides, typically no better than 1 - 10 cm2V-1s-1 at room temperature. Recent reports of room temperature mobilities of ~300 cm2 V-1s-1 in single crystals of La-doped BaSnO3 have therefore generated significant excitement. In addition, BaSnO3has a wide band gap (~ 3 eV), which makes it of interest as a new transparent conducting oxide and as a wide band gap semiconductor for power electronics. Furthermore, it would allow for integration of functional perovskite oxides on a lattice- and symmetry-matched, high-mobility, semiconducting channel.

Electronic devices require the growth of high-quality films with low defect densities. High-mobility BaSnO3 thin films have been challenging to grow. Molecular beam epitaxy (MBE) is a low energetic deposition technique and routinely produces the highest mobility semiconductor and functional oxide films. However, stoichiometry control in MBE of perovskite oxides can be challenging. We show that in the MBE of perovskite stannates using a Sn metal source, volatile SnO consumes all active oxygen in the growth environment, leaving behind only Sn droplets at low growth temperatures. No film growth occurs at high temperatures. We discuss a modified MBE approach, which supplies pre-oxidized SnO
x
. This technique addresses issues in the stoichiometry controls in MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO3. A second challenge is the lack of lattice-matched substrates. We discuss the effect of lattice mismatch on the growth and transport properties of BaSnO3 by comparing the properties of films grown on SrTiO3 and PrScO3 substrates. We show that the carrier mobility doubles as the lattice mismatch is reduced by a factor of two, indicating that high misfit dislocation densities are the main limiting factor in further improving carrier mobilities. We demonstrate room temperature electron mobilities of 150 cm2 V-1s-1 at carrier densities of 7×1019 cm-3 in BaSnO3 films grown on PrScO3 using the modified MBE technique. We will discuss the prospects for further improving the carrier mobilities and reducing the carrier densities.
Band Gap Changes in Zn(1-x)Mnxo Nanomaterials
Authors: Kasim Muhd Firdaus , Kamarulzaman Norlida
Published: February 2020

Mn doped ZnO with different percentages of Mn content (1- 5 mol %) were prepared by a simple sol-gel method. The band gaps of the materials were systematically studied based on the dependence of the dimensions of the nanostructures as well as the effects of increasing Mn content in ZnO materials. It was found that by increasing Mn content in ZnO nanostructures leads to band gap widening with respect to the pure ZnO materials. In order to understand the phenomenon of band gap changes, quantitative X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and microscopy were employed. It was found that band gaps of these materials were affected by both the dimensions of the nanostructures and the presence of the dopant element. Changes in the dimensions of the crystallites affected the crystal structural parameters which in turn affected the band gaps of the materials. Band gap changes for Mn doped ZnO materials are not the same for nano and micro crystallites. XPS shed some light on the band gap changes of the materials.
(Invited) Zinc Oxide As a Potential Material for Future Electronic Device Applications
Authors: Siddiqua Poppy , Shur Michael , O'Leary Stephen K.
Published: February 2020

Zinc oxide is a II-VI compound semiconductor that is in possession of a unique constellation of interesting material properties. While at the present moment zinc oxide is primarily being used as an electronic material for low-field thin-film transistors, transparent conducting oxide contacts, sensing, and field emitter device applications, recent electron transport work has pointed to the potential of this material for high-field and high-frequency electronic device applications. In this paper, we present some recent results on the steady-state and transient electron transport within zinc oxide, suggesting that this material, having higher peak and saturation electron drift velocities than silicon carbide and gallium nitride, may also be considered as an alternative material to silicon carbide and gallium nitride for high-power and high-frequency field effect transistors. Limits on expectations for zinc oxide based device performance will be projected and contrasted with those expected for silicon carbide and gallium nitride based devices. Upon the basis provided by these results, possible future applications for zinc oxide based devices will be suggested.
(Invited) Nanostructured Heterojunction for Enhanced Gas-Sensing Performance
Authors: Sun Xuhui
Published: February 2020

Metal oxide Semiconductor (MOS) materials based gas sensors have been developed in variety of applications such as industrial emission control, civil life, medical diagnosis, and environmental monitoring, due to their irreplaceable advantageous features, such as high sensitivity, small physical size, low cost and simplicity in fabrication. In addition to the material characteristics, heterojunction, based on a unique sensing mechanism, has already been proved to result in the improvement of the sensing performances compared to their single-component semiconductor gas sensors due to the synergetic effect from different sensing materials in the hetero-structure and the heterojunction barrier formed at the interfaces. In this talk, our recent progress on the synthesis of porous MOS heterostructures with nanostructured heterojunction in the thin film, nanowires and 2D nanomaterials will be presented. For example, highly-uniform bilayer and multilayer porous thin films were successfully fabricated using self-assembled soft template and simple sputtering deposition technique. The sensor based on the In2O3/CuO bilayer porous thin film shows obviously improved sensing performance to ethanol at the lower working temperature, compared to single layer counterpart sensors. The sensing mechanism based on p-n hetero-junction, which contributed to the enhanced sensing performance was also experimentally confirmed by a control experiment which the SiO2 insulation layer was inserted between the In2O3 and CuO layers to break the p-n junction. Besides, in this talk I would like to briefly report the progress of the electronic noise based on carbon nanostructures assembled in smart cell phone.
(Invited) Investigation of Phosphorene in Electrochemical Energy Storage Devices
Authors: Koratkar Nikhil
Published: February 2020

Among the family of atomically thin two-dimensional (2D) materials, phosphorene (a monolayer of black phosphorus) has special significance since it offers a direct band gap that lies in-between the zero gap graphene and various large band gap 2D transitional metal dichalcogenides. Phosphorene is an atomically thin sheet in which each phosphorus atom bonds with three neighboring atoms forming a puckered honeycomb structure. So far the research community has mainly focused on the electronic and opto-electronic applications of phosphorene such as logic transistors and photo-detectors. The exploration of this unique material in electrochemical energy storage is still very much in its infancy. In my talk, I will show that incorporation of few-layer nanosheets of phosphorene into a porous carbon nanofiber network (cathode matrix) can significantly improve the cycle life of Lithium-Sulfur (Li-S) batteries. After 500 continuous cycles of charge-discharge, the specific capacity of the Li-S battery with phosphorene is retained above 660 mAh g−1 with only ~0.053% capacity decay per cycle, much better than the baseline battery (without phosphorene) which shows ~0.25% capacity fade per cycle in only 200 cycles under the same test condition. First-principles density functional theory calculations indicate that this improvement is related to phosphorene’s ability to immobilize lithium polysulfides. The binding energy of various lithium polysulfides to phosphorene ranges from 1-2.5 eV, which is significantly greater than a carbon hexatom network (~0.5 eV). Our results also indicate that the presence of phosphorene lowers the polarization, accelerates the redox reaction and improves sulfur utilization in the battery. Such work indicates the promise of phosphorene and will give further impetus to the research community to explore the fundamental science and applications of phosphorene in the context of electrochemical energy storage.
Self-Powered Electrochemical Systems for the Synthesis of Metal Nanoparticles and Their Use in Lactate Detection
Authors: Tsao Yu-Hsiang , Chen Chuan-Hua , Lin Zong-Hong
Published: February 2020

Since the first triboelectric nanogenerator (TENG) was developed in 2012, TENG now has become an energy technology to efficiently convert the mechanical energy into electricity. By using TENG as a power source, numerous self-powered sensing systems toward different targets have been demonstrated and showed their potential. In this study, we used TENG to replace the traditional power source to synthesized different metal nanoparticles in the electrochemical system. The carbon fiber fabrics were adopted as the conductive substrates to grow nanoparticles. The size and density of nanoparticles on the carbon fiber fabrics can be controlled by the electric output from the TENG. In addition, we also showed that the as-prepared carbon fiber fabrics were integrated with TENG and then became a self-powered sensing system. The system exhibited good selectivity and sensitivity toward lactate detection. In addition, the sensing part in the system was designed to be flexible in order to fit the curve of human body. Finally, the self-powered sensing system was successfully demonstrated to detect the lactate concentration in perspiration. In the near future, this device will help people to control their physical function and health immediately. We also believe that it can offer considerable promise for diverse sport, military, and biomedical applications.
(Invited) Printing 3D Gel Polymer Electrolyte in Li-Ion Microbattery Using Stereolithography
Authors: Chen Qiming , Xu Rong , He Zitao , Zhao Kejie , Pan Liang
Published: February 2020

3D li-ion microbattery has gained an increasing importance since the development of microelectromechanical systems (MEMS). Compared with the limited areal capacity for thin-film microbattery, 3D microbattery has the advantage of fully utilizing the limited footprint area without sacrificing the power density. Most of the 3D microbatteries that have been published nowadays require the a) patterning and/or depositing process to define the 3D electrode’s architecture and b) sealing case to ensure the encapsulation for liquid electrolyte. These process increase the difficulty to manufacture 3D microbatteries.

UV-curable gel polymer electrolyte (GPE) is one of the routes for creating low-cost, high-yield 3D microbatteries. By using the micro-stereolithography system, GPE can be built into different 3D shapes. Poly (ethylene oxide) (PEO) has been used as the polymer host in the polymer electrolyte. By incorporating lithium salt and organic solvents as plasticizers into the PEO host, a stable and high-conductivity gel electrolyte can be formed. The GPE combines the mechanical properties of a swollen polymer network with the high ion conductivity of the liquid electrolyte.

Here we demonstrated a method to manufacture 3D gel polymer electrolyte for microbattery. We characterized the GPE membrane by Electrochemical Impedance Spectroscopy (EIS). The result shows a promising ionic conductivity for the use of solid-state li-ion battery. A half-cell has also been assembled for studying the GPE’s cycle performance. The GPE is then fabricated by stereolithography into different 3D structures. SEM picture shows a nano-porous structure in GPE which facilitates the ion transportation. Assembled with electrode material and current collector, the 3D GPE can be built into a 3D microbattery. The microbattery shows a successful operation for 2 cycles, with a capacity of 1.4mAh cm2.
Confined Electrochemical Deposition in Sub-15 nm Space for Preparing Nanogap Electrodes
Authors: Sadar Joshua , Wang Yuan , Qing Quan
Published: February 2020

Nanopore sensing has been the most promising candidate of the next generation of sequencing as it requires no complex labeling or DNA amplification, and the long read length could substantially help the alignment and assembly of repetitive DNAs. However, the existing designs of solid-state nanopore sensors and the preparation strategies face significant challenges such as the scalability and reproducibility of fabrication, lack of control of translocation, and low specificity in read‐out signals. Here we introduce our bottom‐up approach based on confined nanoscale electrodeposition to prepare nanopore devices integrated with transverse self‐aligned electrodes for scaled up production. Our new fabrication strategy would enable accurate control of critical dimensions of the nanopore devices, and new ways for translocation control and recognition tunneling readout of sequence information of the biomolecules.
(Invited) A Versatile Plasmonic Film for Biosensing and Photocatalytic Applications
Authors: Yang Yang
Published: February 2020

Novel Au@TiO2 plasmonic films were fabricated by individually placing Au nanoparticles into TiO2 nanocavity arrays through a sputtering and dewetting process. These discrete Au nanoparticles in TiO2 nanocavities showed strong visible-light absorption due to the plasmonic resonance. Surface-enhanced Raman spectra (SERS) of this plasmonic film showed a high sensityvity to organic molecule at low concentration (down to 0.1 micro molar). Photoelectrochemical studies demonstrated that the developed Au@TiO2 plasmonic films exhibited significantly enhanced catalytic activities towards oxygen reduction reactions with an onset potential of 0.92 V (vs reversible hydrogen electrode), electron transfer number of 3.94, and limiting current density of 5.2 mA cm-2. The deposited Au film thickness remarkably affected the catalytic activities of Au@TiO2, and TiO2 coated with 5 nm Au (Au5@TiO2) exhibited the best catalytic function to reduce oxygen. The plasmon-enhanced reductive activity is attributed to the surface plasmonic resonance of embedded Au nanoparticles in TiO2 nanocavities and suppressed electron recombination.
Voltage Charging Gold-Microtube Membranes for Electroporation
Authors: Martin Charles R , Experton Juliette , Wilson Aaron G.
Published: February 2020

Electroporation of cell membrane occurs when sufficiently large electric field gradients (in the order of kV/cm) are applied to a cell medium. This is routinely accomplished in medicine and biology using voltage pulses above 1 kV in order to incorporate foreign molecules and genes into living cells.1 However, transient pore formation or reversible electroporation is a challenge with such large voltages because of Joule heating, pH changes and ion dissolution that lead to high cell mortality.2 Furthermore, special safety precautions are required. As such, the miniaturization of electroporation devices has been a research interest in order to reach similar electric field gradients with lower voltages.3 It was also shown that these microscopic devices result in higher electroporation yields and better cell viability, although often reducing the cell throughput.

We have developed an electroporation system that consists on charging gold microtubes inside a filter membrane to electroporate Escherichia coli at low voltages (<5 V).4 Supporting our experimental results with theoretical simulations, we have shown that electric field gradients of 4 kV/cm, sufficiently large to reversibly porate the bacteria membrane, were formed inside the gold microtubes. Following the incorporation of exogenous probes inside E. coli with fluorescence microscopy and spectroscopy, we have determined that up to 40% of the bacteria were reversibly electroporated. This is more than an order of magnitude higher than the efficiency obtained with a commercial electroporation device. Finally, cell throughput of >30 million cells per minutes, higher than any previously reported device, were obtained.

Gehl, J. Acta Physiol. Scand.
2003, 177, 437-447.

Lee, W. G.; Demirci, U.; Khademhosseini, A. Integr. Biol.
2009, 1, 242-251.

Geng, T.; Lu, C. Lab Chip
2013, 13, 3803-3821.

Experton, J.; Wilson, A. G.; Martin C. R. Anal. Chem. [Article ASAP]. DOI: 10.1021/acs.analchem.6b03820. Published Online: Nov 17, 2016.
(Invited) Graphene-Based Layer Transfer
Authors: Kim Jeehwan
Published: February 2020

As a strategy to save the cost of expensive substrates in semiconductor processing, the technique called “layer-transfer” has been developed. In order to achieve real cost-reduction via the “layer-transfer”, the following needs to be insured: (1) Reusability of the expensive substrate, (2) Minimal substrate refurbishment step after the layer release, (3) Fast release rate, and (4) Precise control of a released interface. Although a number of layer transfer methods have been developed including chemical lift-off, optical lift-off, and mechanical lift-off, none of those three methods fully satisfies conditions listed above. In this talk, we will discuss our recent development in a “graphene-based layer-transfer” process that could fully satisfy the above requirements, where epitaxial graphene can serve as a universal seed layer to grow single-crystalline III-N, III-V, II-VI and IV semiconductor films and a release layer that allows precise and repeatable release at the graphene surface.
Aged Tris(trimethylsilyl) Phosphite (TMSPi) As a L.I.B. Electrolyte Additive
Authors: Peebles Cameron , Gilbert James A , Sahore Ritu , Garcia Juan , He Meinan , Tornheim Adam , Lu Wenquan , Zhang Zhengcheng , Iddir Hakim , Bareno Javier , Abraham Daniel P , Liao Chen
Published: February 2020

The use of electrolyte additives has been and continues to be an economical and effective approach to enhance the performance and increase the lifetime of lithium ion battery systems. In the presence of additives, the baseline performance of electrolytes can be improved due to the formation of surface films on the electrodes, HF scavenging in the bulk electrolyte, etc. However, the interaction between electrolytes and small molecule additives are rarely studied due to the assumed inertness of the system. While this inert relationship may hold true for many additives, we have found that one commonly used additive, tris(trimethylsilyl) phosphite (TMSPi), demonstrates a dynamic (reactive) relationship when used with a LiPF6-based electrolyte (1.2 M LiPF6 in EC/EMC, 3/7 wt/wt). Our findings suggest that immediately after the addition of TMSPi into the electrolyte, the nature of the electrolyte changes and the properties of the bulk electrolyte are drastically different between immediately making the solution and waiting less than a week. We present electrochemical data comparing freshly prepared (same day) and “aged” (one week) TMSPi-based electrolyte formulations. Our results indicate that the effect of electrolyte aging on cell electrochemistry (LiNi0.5Mn0.3Co0.2O2 /graphite full cells operating between 3.0-4.4 V) can be dramatic with observable differences in impedance, redox behavior, surface film formation and transition metal dissolution from the positive electrode. The data presented sheds considerable light on the possible interactions between additives and electrolyte and are of utmost importance when considering electrolyte formulations for lithium ion batteries.
(Invited) Fundamental and Practical Aspects of Implementing Non PGM Based Cathodes in Low and Medium Temperature PEM Fuel Cells
Authors: Mukerjee Sanjeev , Jia Qingying , Li Jingkun , Pavlicek Ryan
Published: February 2020

Enabling concerted charge transfer at the inner Helmholtz plane of an electrochemical interface is a prelude to higher selectivity and activity for electrochemical processes hitherto not possible with conventional highly dispersed metal and metal alloy electrocatalysts. This presentation will focus on recent shifts away from conventional supported metal and metal oxide based catalysts to organo-metallic and composite metal oxides based structures, which promise orders of magnitude higher turnover frequency and selectivity. Taking oxygen reduction as a theme, this presentation will provide clear comparison of electrrochemcal response between supported metal catalysts (alloys and oxides), especially on noble metals in acidic pH and catalyst based on transition metal nitrogen coordinated systems and multi-phase composite oxides. Electrochemical data will be discussed in the context of spectroscopy, especially in situ synchrotron x-ray absorption spectroscopy (XAS). Here the conventional bulk averaged XANES and EXAFS spectroscopy will be further embellished by unique use of subtractive method referred to as ‘Δ μ technique’. This specially designed subtractive technique using the near edge part of the spectra (x-ray absorption near edge spectra, XANES) has been previously validated and has unprecedented ability to elucidate nature of adsorbed species on transition metals. The unique element specificity and the in situ and operando capability of the XAS spectra in close conjunction with electrochemical data will be used to provide insight on steady state electrocatalytic pathways as a function of various operating conditions and associated applications. Unique structural features of the active sites determined in situ using the extended part of the spectra (i.e., extended x-ray absorption spectra, EXAFS) will be invoked to explain activity difference based on pH and water activity.

Figure 1
(Invited) Datahub for Energy Materials Network
Authors: Sivaraman Chitra , Macduff Matt
Published: February 2020

This talk will provide an overview of the DataHUB being built for the U.S. Department of Energy’s Energy Materials Network (EMN). The DataHUB will be a best-in-class data-serving infrastructure, leveraging standard practices to collect, manage, and curate data to accelerate the process of materials discovery, characterization, and commercial deployment of technologies. It will provide open, uninterrupted, easy, and secure access to codes, models, experiments, simulated data, and journal publications produced by all projects within the EMN consortia. A central repository currently does not exist for the EMN projects and studies. Rather, the data are being stored by the principal investigators at their home institutions and are not easily accessible by other users. Moreover, the information is vulnerable to loss, while the opportunities for cross-cutting integration are, at best, limited. By creating a central hub for data storage, discovery, and access, potential duplication of experiments and studies along with other efforts that could delay scientific progress can be avoided. The DataHUB’s short-term objective will be to provide this repository service for data produced by the EMN consortia. The central hub will allow consortia members to focus on the science, research, and analysis while the DataHUB will maintain data security and access, as well as offer a standardized approach to curate the data. The DataHUB will provide autonomy to each consortium for creating the content of the portal and tools for their specific projects. In addition, the DataHUB will be extended to enable seamless integration of multidisciplinary scientific investigations and analyses to address common material challenges spanning all EMNs.
Bis-Annulation By Electrocatalysis
Authors: Hussaini Syed Raziullah , Chiba Kazuhiro , Okada Yohei , Yamaguchi Yusuke , Yasushi Imada , Shoji Takao
Published: February 2020

We recently reported the application of electrocatalysis to promote Diels-Alder type reactions between electronically mismatched substrates. In this talk, we will describe our new results which showcase bis-annulations. A catalytic amount of electricity was used in these reactions to make two six-rings on bis-anethole derivatives. Currently, more diene partners are under investigation to see the scope of the reaction.
Tetranitrocalix[4]Arene Tetraradical Tetraanion As an Electrochemically Generated Ligand
Authors: Ludvík Jiří , Liška Alan , Vojtíšek Pavel
Published: February 2020

A tetraradical tetraanion is a stable product of 4-electron reduction of cone-5,11,17,23-tetranitro-25,26,27,28-tetrapropoxycalix[4]arene in nonaqueous dimethyl-formamide (DMF) [1]. It represents an electrochemically generated ligand which is able to coordinate all alkali metal ions. The existence of these complexes was recently proved by DC-polarography, cyclic voltammetry and UV-VIS spectroelectrochemistry. Observed stoichiometries are 2:1 (for Li+, Na+, Cs+), 3:1 (Rb+, Cs+) and 4:1 (K+). The complexes are kinetic labile and they have character of ion pairs between negatively charged nitroradical group and metal cations. The „normalized“ values of the stability constants were compared with stability constants of ionic pairs of alkali metals with nitrite anions. About three orders higher values for calix[4]arene radicals can be explained by a „structural vector“. Four charged and oriented nitroradicals on calix-scaffold as donor groups form considerably higher „field for electrostatic interaction“ than randomly oriented simple anions. The same type of interaction was revealed also for cone-5,11,17,23-tetranitro-25,26,27,28-tetrakis(ethoxycarbonylmethoxy)calix[4]arene. This compound was originally suspicious of binding alkali metal ions by ester groups on the lower rim, however, the experimental data exclude this possibility.

Reference

[1] A. Liška, P. Vojtíšek, A.J. Fry, J. Ludvík, Electrochemical and Quantum Chemical Investigation of Tetranitrocalix[4]arenes: Molecules with Multiple Redox Centers, J. Org. Chem. 78 (2013) 10651-10656.
Electrochemical Bio-Oil Upgrading at Mild Conditions
Authors: Holladay Jamelyn , Padmaperuma Asanga , Lilga Michael , Lister Tedd E. , Diaz Luis A. , Petkovic Lucia M.
Published: February 2020

We are using a PEM system to demonstrate bio-oil upgrading at mild conditions. Bio-oil is a mixture of hundreds of inorganic and organic compounds with an aqueous and non-aqueous phase. It contains reactive, acidic and oxygenated species which cause condensation and polymerization reactions. It is long believed that active groups such as phenolics and carbonyls are responsible for these reactions. Therefore, prior to use as a transportation fuel, the oils need to be stabilized (upgraded) to hydrogenate unstable and/or corrosive species. Conventional bio-oil hydrogenation occurs at moderate temperatures (300°C) and hydrogen pressures up to 2000psi. We have modified a PEM fuel cell to perform bio-oil hydrogenation to stabilize the more reactive compounds using protons and water as the hydrogen source at room temperature. Electrochemical hydrogen generation is a common competing reaction. This eliminates the high temperature and externally supplied high pressure hydrogen which may decrease the cost of bio-fuels and products. By modifying the PEM cell structure and electrode materials promising results have been observed where significant hydrogenation was found. The novel cell structures and electrode materials resulted in improved current efficiencies for electrochemical reduction of organic species. A description of work conducted and a discussion of results will be presented.
Trifecta of Ionic Liquid As Solvent, Electrolyte, and Mediator
Authors: Shimakoshi Hisashi , Takamatsu Kanako , Hisaeda Yoshio
Published: February 2020

In recent years, ionic liquids have been the subject of considerable interest as promising media for chemical reactions including of electroorganic synthesis because of their unique characteristics such as low melting point, negligible vapor pressure, non-flammability, high conductivity and the good solubility of many organic and inorganic compounds as well as biomaterials.1 In the development of ionic liquid study, here we reported the synthesis of redox active ionic liquids, such as 1-ethyl-4-(methoxycarbonyl)pyridinium bis(trifluoromethanesulfonyl)amide (P1
•
TFSA) and 1-ethyl-3-(ethoxycarbonyl)pyridinium bis(trifluoromethanesulfonyl)amide (m3
•
TFSA). These redox active ionic liquids were synthesized from its iodide form by anion exchange reaction and were characterized by NMR, UV-VIS, IR and elemental analyses. These compounds showed redox waves around -0.6~-1.5 V vs. Ag/AgCl and were worked as electron mediator for the electroorganic reaction (Figure 1).

References

1) J. P. Hallett, T. Welton, Chem. Rev.
2011, 111, 3508.

Figure 1
Mechanistic Insight into the Electrocatalytic Hydrogenation and Electroreduction of Furfural
Authors: Chadderdon Xiaotong , Chadderdon David J , Matthiesen John Edward , Tessonnier Jean-Philippe , Li Wenzhen
Published: February 2020

Electrochemical reduction of biomass-derived platform chemicals is an emerging route for biofuels and chemicals production, where renewable electricity drives reactions on electrodes without the need for external hydrogen supply.1-3 However, the mechanisms governing electrochemical reduction of biomass-derived furanic compounds and its competition with hydrogen evolution reaction (HER) remain unclear. In this talk, we investigate the electrochemical reduction of furfural on copper electrodes for the production of 2-methylfuran (an important potential biofuel additive), furfuryl alcohol (a valuable chemical building block), and dimerization products. Through novel electrochemical techniques, we distinguish between two mechanisms – electrocatalytic hydrogenation (ECH) and outer-sphere electroreduction (ER). Understanding of the underlying mechanisms enables us to tune product selectivity and the competition between ECH, ER, and HER by varying reaction conditions including cathode potential, initial furfural concentration and electrolyte pH. Cyclic voltammetry and bulk electrolysis results clarify the reaction pathways of 2-methylfuran and furfuryl alcohol formation under these conditions. We demonstrate that electrochemical reduction is a promising route for selective furfural conversion and highlight the importance of the underlying mechanisms. These findings can be applied to related biomass-derived platform chemicals including 5-(hydroxymethyl)furfural and other carbonyl-containing compounds.

References:

1. Xin, L.; Zhang, Z.; Qi, J.; Chadderdon, D. J.; Qiu, Y.; Warsko, K. M.; Li, W., Electricity storage in biofuels: selective electrocatalytic reduction of levulinic acid to valeric acid or gamma-valerolactone. ChemSusChem
2013, 6, 674–686.

2. Matthiesen, J. E.; Suástegui, M.; Wu, Y.; Viswanathan, M.; Qu, Y.; Cao, M.; Rodriguez-Quiroz, N.; Okerland, A.; Kraus, G.; Raman, D. Raj; Shao, Z.; Tessonnier, J.-P., Electrochemical Conversion of Biologically Produced Muconic Acid: Key Considerations for Scale-Up and Corresponding Technoeconomic Analysis. ACS Sustainable Chem. Eng.
2016, 4, 7098–7109.

3. Suástegui, M.; Matthiesen, J. E.; Carraher, J. M.; Rodriguez Quiroz, N.; Okerlund, A.; Cochran, E. W.; Shao, Z.; Tessonnier, J.-P., Combining Metabolic Engineering and Electrocatalysis: Application to the Production of Polyamides from Sugar. Angew. Chem. Int. Ed.
2016, 55, 2368–2373.
Understanding the Metabolic Activation of Therapeutic Agents with Molecular Electrochemistry: The Example of Metallocifen Anti-Cancer Drug Canditates
Authors: Amatore Christian Andre , Buriez Olivier , Labbe Eric
Published: February 2020

Organometallic chemistry has allowed the design and emergence of a new class of metal-based bioactive molecules and a variety of drugs already used or being tested against cancer. In this field, cisplatin is well-known and widely used clinically. However, recent contributions are focusing on the functionalization of clinically validated purely organic drugs with complexes derivatized by a metallocene group. This approach has been shown to exalt the anti-cancer properties of the organic moiety, and has been successfully used to design ferrocifens. These complexes involve a ferrocenyl group covalently grafted onto the tamoxifen skeleton, the current gold standard for endocrine breast cancer therapy. Based on the same strategy, several original ruthenocene- and osmocene-tamoxifen derivatives have been recently synthesized and were also successfully tested against breast and other cancer cells.

This communication will detail how the development of such potent metallodrugs was directly bearing on the accurate mechanistic understanding of their electron transfer activation provided by the synergistic combination of molecular electrochemistry and biological approaches.
Bio-Inspired Artificial Electron Transfer in Bioelectrocatalysis
Authors: Minteer Shelley D.
Published: February 2020

Biological systems have complex electron transport pathways that can be used as an inspiration in designing electrodes for bioelectrocatalysis. This presentation will detail the use of microbial biology as an inspiration for designing electrodes capable of hetergeneous reduction to produce ammonia. In this work, we have studied the use of nitrogenase for bioelectrocatalysis, because this MoFe protein is capable of electrosynthesis of ammonia. Although this protein has been studied by biologists in solution or in cells for decades, it has never been effectively wired to an electrode for heterogeneous electrosynthesis. In this work, we detail strategies for electron transport betweent he MoFe protein and the electrode, as well as strategies for immobilization of the enzyme. We will demonstrate bioelectrocatalysis, as well as electrosynthesis assays of the production of ammonia.