bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Design and Sensitivity Analysis of Non-Aqueous Lithium O2 Batteries
Authors: Raoufi Arman , Torayev Amangeldi , Thangavel Vigneshwaran , Franco Alejandro A. 
Published: February 2020

In this study, a gradient-based optimization algorithm is used for the computational design and optimization of a non-aqueous lithium-O2 battery. The sensitivity analysis and numerical optimization capabilities are appended to the multiscale framework previously developed at LRCS for the discharge behavior of this type of batteries. The transport of oxygen in the porous cathode is modeled using Fick’s law at the continuum scale, by assuming isothermal conditions. A micro-scale model predicting the discharge product morphology is coupled to the continuum one. The final discharge product is assumed to form, through both the surface limited thin film growth mechanism and the solution phase reaction mechanism. The cathode microstructure in the model is based on experimentally measured PSD (pore size distribution). A detailed reaction mechanism considering the microstructural properties of the cathode, the surface limited reaction, surface thin film growth and solution phase reaction is used. The sensitivity analysis for the Lithium-O2 cell is performed using the finite difference approach. Sensitivity derivatives are used to identify the variables that have the most significant impact on design performance of the battery. This information is helpful prior to an optimization study as it can be used to remove design parameters that do not strongly influence. Design variables investigated are the O2diffusion coefficient, the cathode porosity, temperature, separator porosity and the cathode thickness. The cell performance is optimized and improved using a quasi-Newton algorithm. In the quasi-Newton algorithm, sensitivity derivatives are utilized in determining a search direction that maximizes a cost function representing the cell capacity. This work provides a comprehensive receipt on the implementation of efficient algorithms devoted to the predictions of optimized cell designs. Design guidelines arising from the computational results are discussed from an engineering perspective.

References:

[1] Kan-Hao Xue, Trong-Khoa Nguyen, and Alejandro A. Franco, “Impact of the Cathode Microstructure on the Discharge Performance of Lithium Air Batteries: A Multiscale Model”, J. Electrochem. Soc. 2014 volume 161, issue 8, E3028-E3035.
[2] Kan-Hao Xue, Euan McTurk, Lee Johnson, Peter G. Bruce, and Alejandro A. Franco, “A Comprehensive Model for Non-Aqueous Lithium Air Batteries Involving Different Reaction Mechanisms”, J. Electrochem. Soc. 2015 volume 162, issue 4, A614-A621.
Electrochemical Deposition of Tin Selenide (SnSex) Thin Films
Authors: Howell Pauline , Stickney John Lewellen 
Published: February 2020

Tin selenide belongs to group IV-VI chalcogenide. Its electrical, optical, and structural properties are attractive for having both direct and indirect bandgaps, and its potential for being a 2D material. Tin selenide is also a component of Cu2ZnSn(S,Se)4 and can be combined with other binary compounds to form absorber materials for photovoltaic applications 1. In this study, tin selenide thin films (SnSex) were grown on gold substrates using electrochemical atomic layer deposition (E-ALD) 2. E-ALD works by depositing one component followed by the other, keeping the condition simple at room temperature using a three electrode flow cell. A monolayer (ML) of the compound completes one cycle. This type of deposition process adds control to the compound growth by limiting the amount of deposit to less than a ML per cycle. Potentials for deposition were selected based off of cyclic voltammetry of Sn and Se. The Sn deposition potential was varied to see the effect on the thin films. Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to characterize the composition and structure of the deposits. Results from XRD and Raman suggest that the tin selenide films contain both SnSe and SnSe2. Particle shapes of the deposit vary as a function of Sn deposition potential. Changing the deposition potential of Sn also alters the ratios of Sn and Se. Future studies will include quantification of the SnSe and SnSe2 present, as well as optimization of the homogeneity thin films.
References
1. Czerniawski, J. M.; Perdue, B. R.; Stickney, J. L., Potential Pulse Atomic Layer Deposition of Cu2Se. Chem Mater
2016,
28 (2), 583-591.
2. Stickney, J. L.; Villegas, I.; Suggs, D. W.; Gregory, B. W., Electrochemical Atomic Layer Epitaxy (ECALE). Abstr Pap Am Chem S
1991,
201, 289-Coll.
(Invited) Photoelectrocatalysis: Solar-Assisted Hydrogen Production in Microgravity Environments
Authors: Brinkert Katharina , Richter Matthias Hermann , Liedtke Janine , Mitrovic Slobodan , Akay Ömer , Giersig Michael , Matsushima Hisayoshi , Fukunaka Yasuhiro , Lewerenz Hans Joachim 
Published: February 2020

Artificial photosynthesis systems, which follow the concept of the Z-scheme of natural photosynthesis, are presently being realized as catalyst-functionalized photovoltaic tandem devices for the photoelectrochemical oxidation of water and the simultaneous generation of hydrogen as a so-called “solar fuel”. The successful implementation of an efficient photoelectrochemical (PEC) water splitting cell is not only a highly desirable approach to solving the energy challenge on earth: an effective air revitalization system generating a constant flux of O2 while simultaneously recycling CO2 and providing a sustainable fuel supply is also essential for the International Space Station and long-term space missions, where a regular resupply from earth is not possible.
Here, we present the photoelectrochemical production of hydrogen in microgravity environments on p-type indium phosphide electrodes with deposited rhodium electrocatalysts. Our findings indicate that microgravity has a significant impact on the gas bubble evolution behaviour and the mass transfer rate of the evolved hydrogen gas on the electrode surface. Furthermore, microgravity influences the current-voltage characteristics and the overall solar-to-hydrogen efficiency of the catalyst functionalized semiconductor-based half-cell. Further experiments with nanostructured rhodium catalysts fabricated by shadow nanosphere lithography on the InP surface suggest that the structure of the electrode surface plays a significant role for the gas bubble evolution behaviour and for the further the development of efficient prototypes for solar-assisted water splitting and hydrogen production that operate in micro- and hypergravity environments.
Electrodeposition of Germanene from Aqueous Solution, pH 9.0
Authors: Bui Nhi , Ledina Maria , Jung Jin , Reber Theodore James , Stickney John Lewellen 
Published: February 2020

The group IV elements including C, Si, Ge and Sn have all shown to form 2D allotropes that have drastically different properties from their bulk component. Following the discovery of graphene and silicene, the study of germanene has garnered increasing interest and has raised many questions pertaining to its exact structure, properties and formation. A number of theoretical calculations have proposed structures for germanene with varying bond distances and degree of buckling. Some experimental works suggest that germanene could be deposited via molecular beam epitaxy (MBE) using germanium wafer as source. This study proposes an alternative route of forming germanene via electrodeposition 1. Electrochemical scanning tunneling microscopy (EC-STM), and in situ surface-enhanced micro Raman (SERS) are used as means to gather information on the deposition process of Ge on Au(111). The optimal condition to grow a single atomic layer of Ge was selected based on atomic resolution images from EC-STM. Various phases of Ge were observed, detailing the transition from a precursor stage to complete honeycomb rings of germanene. The nucleation process started with growth of some small Ge domains, followed by a lateral expansion through the edges. After forming the second layer, the surface became passivated as expected for an insulating gap of a 2D bulk material. Current efforts are being directed toward forming a thicker germanene film using our previously developed methodology called Ge-Te bait-and-switch electrochemical ALD cycle 2-4. The approach involves using Te as a capping layer and as a basal support to allow Ge to form new layer.
This work is supported by the National Science Foundation.
References
1. Ledina, M. A., Liang, X., G. Kim, Y., Jung, J., Perdue, B., Tsang, C., Soriaga, M.P., Stickney, J. L., Investigations into the Formation of Germanene using Electrochemical Atomic Layer Deposition (E-ALD). ECS Transaction
2015,
66(6), 129-140.
2. Liang, X. H.; Jayaraju, N.; Thambidurai, C.; Zhang, Q. H.; Stickney, J. L., Controlled Electrochemical Formation of GexSbyTez using Atomic Layer Deposition (ALD). Chem Mater
2011,
23(7), 1742-1752.
3. Liang, X. H.; Kim, Y. G.; Gebergziabiher, D. K.; Stickney, J. L., Aqueous Electrodeposition of Ge Monolayers. Langmuir
2010,
26(4), 2877-2884.
4. Liang, X. H.; Zhang, Q. H.; Lay, M. D.; Stickney, J. L., Growth of Ge Nanofilms Using Electrochemical Atomic Layer Deposition, with a "Bait and Switch" Surface-Limited Reaction. J Am Chem Soc
2011,
133 (21), 8199-8204.
The Effect of Defects on Time Dependent Dielectric Breakdown Acceleration in TiN/ZrO2/Al2O3/p-Ge Gate Stacks
Authors: Ding Yiming , Misra Durgamadhab , Tapily Kandabara , Clark Robert D. , Consiglio Steven , Wajda Cory S. , Leusink Gert J. 
Published: February 2020

Introduction of a thin GeO2 as the interfacial layer (IL) seems to be beneficial for formation of high-k gate stacks on germanium substrate. The thickness of GeO2/GeOx impacts the overall equivalent oxide thickness (EOT) because of its low dielectric constant compared to high-k layer. Current trends indicate that the formation of appropriate thickness of GeOx or GeO2 between high-k and Ge substrate seems to have low interface state density (D
it). Since ZrO2 showed lower leakage current than HfO2 with similar dielectric high-k stack, ZrO2/Al2O3 bilayer as gate dielectric is becoming popular. Even though excellent gate stacks on germanium substrate has been demonstrated the reliability and the impact of interfacial layer is still unknown.
This work investigates the p-Ge/Al2O3/ZrO2/TiN gate stacks with thin GeO2 or GeOx layer, formed when the gate stack was exposed to pre- or post-deposition slot plane antenna plasma oxidation (SPAO). The post Al2O3/ZrO2 deposition SPAO forms relatively thicker GeO2 and post Al2O3 deposition SPAO forms thinner GeO2 whereas pre-deposition SPAO forms thin fragmented GeOx layer at the interface. We have observed that the relatively thicker GeO2 interfacial layer formed after the post Al2O3/ZrO2 deposition SPAO degraded faster during time dependent dielectric breakdown (TDDB) measurements on substrate injection mode compared to the thin GeO2 or GeOx interfacial layers (Fig. 1). The improvement in TDDB degradation for thinner interfacial layer thickness suggests that electrons tunnel through the thinner GeOx IL, and TDDB measured the quality of Al2O3 rather than IL.
The TDDB characteristics in gate injection mode suggests that the SPAO can significantly affect the TDDB characteristics GEI mode (Fig. 1). The SPAO treatment effectively removes the trap centers in ZrO2 and Al2O3 layers when SPAO was performed after the gate stack deposition. By employing carrier transport mechanisms as a function of temperature in both gate and substrate injection mode we were able to identify the traps that contributes to the TDDB degradation. The trap center (f
t1 = 0.13 eV) observed in the ZrO2 when ZrO2 is not subjected to the SPAO, i.e. pre-deposition SPAO. This trap f
t1 (0.13 eV) was eliminated for post Al2O3/ZrO2 deposition SPAO. While defects in the ZrO2 layer determines the TDDB characteristics in gate injection mode the GeO2 or GeOx interfacial layer thickness determines the TDDB degradation in substrate injection mode.

Figure 1
Multi-Wavelength Raman Characterization of Epitaxial Silicon Wafers for In-Line Process Characterization and Monitoring Applications
Authors: Yoo Woo Sik , Ishigaki Toshikazu , Kang Kitaek 
Published: February 2020

Epitaxial Si wafers are widely used for high performance advanced memory devices and CMOS image sensor (CIS) device manufacturing. Surface morphology observation and resistivity measurements are frequently done as quick in-line quality monitoring of epitaxial Si layers. High resolution X-ray diffraction (HRXRD) and etch pit characterizations are done for randomly selected wafers. However, these conventional characterization techniques are not sensitive enough to detect small quality variations in epitaxial Si wafers.
For Si wafers with multiple epitaxial layers and different dopant concentrations, the conventional characterization techniques are even less useful. Introduction of new epitaxial characterization techniques is strongly desired for effective in-line process monitoring. A non-contact, in-line characterization technique, with virtual depth profiling capability, would be beneficial for proper characterization of Si wafers with multiple epitaxial layers.
In this study, we have characterized 200 mm and 300 mm Si wafers with triple epitaxial layers using multiwavelength, high resolution Raman spectroscopy. Ninety three (93)-point wafer mapping measurements were performed on all wafers, Statistics of Raman signal intensity, shift and full-width-at-half-maximum (FWHM) values, under different excitation wavelengths, were extracted and compared with two types of reference Si wafers (prime Si wafers and reclaimed Si wafers). Significant variations in Raman signal intensity, shift and FWHM were measured between reference wafers and epitaxial wafers, indicating potential Si lattice stress and crystallinity. Excitation wavelength dependence of Raman signal intensity, shift and FWHM also indicated variations in Si lattice stress and crystallinity of epitaxial layers in the depth direction. Non-contact multiwavelength Raman measurements are very sensitive to the quality of epitaxial Si layers and are effective as a complimentary in-line process characterization and monitoring technique.

Figure 1
(Invited) Effect of Temperature and 5 Mev Proton Irradiation Damage on Performance of b-Ga2O3 Photodetectors
Authors: Ren Fan , Pearton Stephen J. , Ahn Shihyun , Kim JiHyun , Jung Younghun , Oh Sooyeoun , Mastro Michael A , Hite Jennifer K , Eddy Charles R. 
Published: February 2020

Effect of temperature and MeV protons at doses from 1013 -1015 cm-2 on photo-response to 254 nm wavelength, and blindness to 365 nm light, of planar photodetectors fabricated on β-Ga2O3 films grown on Al2O3 by metalorganic chemical vapor deposition. Ohmic contacts were formed by Si-implantation and annealing at 900ºC, followed by deposition of Ti/Au metallization. The photocurrent induced by 254 nm illumination increased monotonically with temperature, from ~2.5 x10-7 A at 25 ºC to ~2.2 x10-6 A at 350 ºC at a fixed 254 nm light intensity of 760 µW/cm2. The temperature dependent photo-to-dark current ratio (PDCR) for this wavelength was 328 at room temperature and decreased to ~9 at 350ºC. The responsivity increased from 5 to 36 A/W over this temperature range, with corresponding external quantum efficiencies of 2.5 x103 % at 25ºC and 1.75 x104 % at 350ºC. Similarly large numbers reported for Ga2O3 photodetectors have previously been ascribed to carrier multiplication effects.
For the effect of 5 MeV protons irradiations, the photocurrent increased with dose due to the introduction of damage from non-ionizing energy loss by the protons. The total calculated vacancy concentration increased from 5x1015-5x1017 cm-3 over the dose range investigated. The dark current increased in proportion with the implant dose, leading to a decrease in the ratio of photocurrent to dark current. The photocurrent induced by 254 nm illumination increased with dose, from ~0.3 x10-7 A at 25 ºC for a dose of 1013 cm-2 to ~10-6 A at a dose of 1015 cm-2 at a fixed light intensity of 760 µW/cm2. The photo-to-dark current ratio decreased from ~60 in the control samples to ~9 after proton doses of 1015 cm-2, with corresponding external quantum efficiencies of ~103 % in control samples, ~2 x103 % for a dose of 1013 cm-2 and 104 % for a dose of 1015 cm-2. The mechanism for the increase in photocurrent is introduction of gap states, since the dark current of the photodetectors was increased by illuminating with sub-bandgap (red or green laser light) for the proton irradiated samples.
Characterization of Electrochemically Gated Graphene Field-Effect Transistor for Bioelectronic Applications
Authors: Asgarifar Sanaz , Inácio Pedro Carrilho , Mestre Ana , Hubbard Peter , Borme Jérôme , Machado George , Alpuim Pedro , Gomes Henrique Leonel 
Published: February 2020

Abstract

This work provides an experimental characterization and equivalent circuit modelling of electrochemically gated field effect transistors (EGFETs) using a graphene layer. The aim is to demonstrate the detection limit of these sensing devices for bioelectronics applications. Towards that, we present a detail study of the; (i) sources of intrinsic noise, (ii) the effect of ionic density in charge transfer resistance and (iii) the existence of parasitic conducting paths in the surrounding electrolyte.
To investigate the liquid-based applications of graphene based EGFETs, quantifying the basic physical properties of graphene/solution interface is crucial. Towards that, we present a detail study of zero bias charge transfer resistance by using different type of ionic solutions and cell culture mediums. Measurements of the electrical noise were also performed to determine the EGFET detection limit.
The performance of the EGFET to record the electrophysiological signals was evaluated using adult zebra fish heart and electrogenic cell cultures. The electrocardiogram of the zebrafish heart was monitored with signal-to-noise-ratio higher than 7.
This contribution also discusses the application of graphene based EGFETS to measure electrophysiological signals in cell cultures. For instance, ultra-week extracellular signals resulting from cell metabolic activity or low frequency calcium waves.

Keywords.
Graphene, electrochemically gated field effect transistor, charge transport, intrinsic noise, extracellular signals.

Figure 1
(Invited) Non-Volatile Redox Transistors for Low Power Computing and Brain-Machine Interfaces
Authors: Talin Albert Alec 
Published: February 2020

The widely anticipated end to Moore’s law and the growing demand for low power computing systems capable of learning, image recognition and real-time analysis of large streams of unstructured data has spurred intense interest in neural algorithms for brain-inspired computing. The brain is capable of massively parallel information processing while consuming only ~1- 100 fJ per synaptic event. Inspired by the efficiency of the brain, CMOS-based neural architectures and tunable resistance elements (memristors) are being developed for low-power pattern recognition and machine learning. However, the volatility, design complexity and high supply voltages for CMOS architectures on one hand, and the stochastic and energy-costly switching of memristors on the other significantly complicate the path to achieve the extreme interconnectivity, information density, and energy efficiency of the brain using either approach. To overcome these limitations, we have recently demonstrated a Li-ion synaptic transistor for analog computation (LISTA).1 LISTA is an all solid-state, non-volatile redox transistor (NVRT) with a resistance switching mechanism based upon the intercalation of Li-ion dopants into a channel of Li1-xCoO2. An NVRT differs from previously described electrochemical transistors in that dopants cannot diffuse out of the channel (after relaxation of applied bias) without an external source of charge to facilitate oxidation and liberate them as ions in a surrounding electrolyte. This is identical to the charge storage mechanism in batteries, which require external current sources to drive charge/discharge redox reactions. A major advantage of the LISTA device is that resistance switching can occur without inducing large structural transformations that are common for memristive devices, such as filament formation or amorphous-to-crystalline phase transformation. In my talk I will show that the structurally stable, diffusion-driven switching mechanism of Li intercalation allows LISTA to operate with a low ‘write’ noise, a near linear response to ‘write’ operations, and orders of magnitude lower switching voltages and currents. Furthermore, our simulations of the device physics demonstrate that scaled LISTA devices will have orders of magnitude lower energy consumption than any resistive memory device to date, and could operate as part of a neural architecture with an energy efficiency matching the brain. Finally, I will introduce an NVRT device based entirely on organic polymers fabricated on flexible substrates. Such devices could in principle form direct interfaces with the brain opening up the opportunity to build advanced neural prostheses with integrated brain-machine interfaces.
1.Fuller, E. J.; Gabaly, F. E.; Léonard, F.; Agarwal, S.; Plimpton, S. J.; Jacobs-Gedrim, R. B.; James, C. D.; Marinella, M. J.; Talin, A. A., Li-Ion Synaptic Transistor for Low Power Analog Computing. Advanced Materials
2016, DOI: 10.1002/adma.201604310