bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Reliability and Scaling Perspectives of HfO2-Based OxRAM
Authors: Cagli Carlo , Sandrini Jury , Sassine Gilbert , Robayo Diego , Hammad Ismail , Molas Gabriel , Gaillard Fred
Published: May 2020

OxRAM is a strong candidate to replace embedded Flash technology at scaled nodes. This is justified by several considerations but mainly driven by the low cost of integration and very high compatibility with standard CMOS technology. Yet OxRAM faces tremendous challenges in terms of reliability, variability and scaling. In this paper we review the reliability of our Ti/HfO2(5nm)/TiN cell. Controlling LRS and HRS resistance distributions can be achieved with a proper write/erase algorithm design and it is a key point to enable large array integration. A proper write/erase sequence ensures long bit endurance up to 107 cycles. Data retention is then evaluated at 125, 165, 200 and 260 °C showing the impact of device aging on retention performance. Next, we show how the OxRAM cell can be successfully integrated with a short-channel (L=30nm) 28nm-like low voltage MOS selector and we demonstrate the operability of the 1T1R device with a special attention to the transistor reliability. Eventually, we present our results on a BEOL selector for crossbar applications.
(Invited) Gate-All-Around Nanosheet Field-Effect Transistors for Advanced Logic and Memory Applications: Integration and Device Features
Authors: Veloso Anabela , Matagne Philippe , Eneman Geert , Mertens Hans , Chasin Adrian , Simoen Eddy , Horiguchi Naoto
Published: May 2020

We report on gate-all-around (GAA) field-effect transistors (FET) consisting of either vertically stacked lateral nanowires (NW)/nanosheets (NS) or vertical NW/NS for ultra-scaled, high-density logic and memory applications, respectively. The first type of GAA NS FETs is widely considered to be the most promising and mature candidate to replace finFETs for sub-5nm technology nodes in the logic roadmap. However, though sharing many fabrication elements, these devices face several specific technological challenges to enable their implementation into manufacturing, some of which will be addressed and evaluated in this paper. Furthermore, we will also present and discuss various critical integration features required to build vertical FETs, highlighting some of the key advantages feasible with the use of a replacement metal gate scheme in their fabrication flow, e.g.: shrinkage of the channel’s cross-sectional area for improved electrostatics, without impacting the source/drain (S/D) series resistances (RS/D); ION improvement thanks to stress-induced enhanced mobility values.
Whether Ge-Rich ZrO2 and Ge-Rich HfO2 Materials Have Similar Reaction on Annealing Treatment?
Authors: Khomenkova Larysa , Lehninger David , Agocs Emil , Petrik Peter , Portier Xavier , Korsunska Nadiia , Melnichuk Oleksandr , Gourbilleau Fabrice , Heitmann Johannes
Published: May 2020

The properties of Ge-HfO2 and Ge-ZrO2 films were studied versus Ge content and annealing temperature by means of Raman scattering, FTIR and X-ray diffraction methods. Ge-HfO2 films with [Ge]<5 at.% were polycrystalline, whereas higher Ge content stabilized amorphous structure that was stable for T<600°C. The T increase caused the formation of Ge clusters and tetragonal HfO2 phase. This latter appeared at T=600-670°C, while the Ge clusters crystallized at T=700-800°C. Unlike to Ge-rich HfO2 films, as-deposited Ge-ZrO2 films and those annealed at T≤600°C were amorphous. In these films, formation of Ge clusters and their crystallization occurred at T=640-700°C depending on Ge content, whereas ZrO2 phase crystalized at T=680-700°C that allowed to form Ge nanocrystals in amorphous matrix at T=640-680°C. For T>800°C, the films showed appearance of monoclinic HfO2 or ZrO2 phases that was explained by the Ge content decrease via volatile GeO formation. Obtained results supported theoretical prediction of the stability of tetragonal phases in these oxides via Ge doping. However, our results showed also some difference in the phase separation process of Ge-rich HfO2 and Ge-rich ZrO2 upon thermal treatment.
(Invited) Band Line-up of High-k Oxides on GaN
Authors: Mitrovic Ivona Z. , Das Partha , Jones Leanne , Gibbon James , Dhanak Vinod R. , Mahapatra Rajat , Partida Manzanera Teresa , Roberts Joseph W. , Potter Richard J , Chalker Paul R. , Cho Sung-Jin , Thayne Iain G
Published: May 2020

We present comprehensive experimental work on TixAl1-xOy (with x = 9%, 16%, 25%, 36%, 100%) and GaxAl1-xOy (x = 5%, 20%, 80% and 95%) fabricated using atomic layer deposition with the aim of achieving favorable band alignment with GaN for device applications. The permittivity, k, has been found to be enhanced from ~10 for 9% Ti to 76 for TiO2, but brings unfavorable band line-up and a small conduction band offset (< 0.1 eV) with GaN for all Ti% studied. On the other hand, GaxAl1-xOy (x = 5%, 20%) films show substantial increase of the band gap from 4.5 eV for Ga2O3 to 5.5 eV for x = 5% Ga and 6.0 eV for x = 20% Ga in mixed oxides and a strong suppression of leakage current in associated metal insulator semiconductor (MIS) capacitors.
Mid-Wavelength Infrared Responsivity of Colloidal Quantum Dot/Organic Hybrid Photodetectors
Authors: Hafiz Shihab Bin , Al Mahfuz Mohammad Mostafa , Ko Dong-Kyun
Published: May 2020

Colloidal quantum dot/organic hybrid materials approach offer a path toward engineering solution-processed photodetectors with extended spectral responsivity in the infrared. We demonstrate this approach in the technologically important thermal infrared region of mid-wavelength infrared, utilizing a solution blend of Ag2Se colloidal quantum dots and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We report on the device fabrication and their optical, electrical, and optoelectronic properties. At room temperature, a responsivity of 0.2 mA/W was measured under 5 μm irradiation and 5 V bias. The new hybrid optoelectronic film demonstrated in this study brings the advantage of cost-effectiveness and greater fabrication versatility than the single crystal or epitaxial semiconductors that comprise today’s infrared technologies.
(Invited) Second Harmonic Generation: A Powerful Non-Destructive Characterization Technique for Dielectric-on-Semiconductor Interfaces
Authors: Ionica Irina , Damianos Dimitrios , Kaminski Anne , Blanc-Pélissier Danièle , Ghibaudo Gerard , Cristoloveanu Sorin , Bastard Lionel , Bouchard Aude , Mescot Xavier , Gri Martine , Lei Ming , Larzelere Brian , Vitrant Guy
Published: May 2020

The second harmonic generation (SHG) proved to be a very promising characterization technique for dielectric-semiconductor interfaces because it is sensitive, non-destructive, can be applied directly on wafer, at different stages of wafer processing. The method, based on non-linear optics effects, is measuring a signal encompassing the “static” electric field at the dielectric-semiconductor interface which is directly related to the oxide charges Qox and to the interface state density Dit. A general methodology for Qox and Dit extraction from SHG measurements requires (i) calibration based on parameters obtained by classical electrical methods and (ii) modeling to capture the optical propagation phenomena that impact the SHG signal. In this paper, we discuss these issues based on a review of our recent advances on how to exploit SHG for dielectrics on semiconductor characterization.
Dynamic Observation of Electromigration in High Density Electroplated Nanotwinned Copper through in-Situ TEM
Authors: Shen Fang-Chun , Huang Chih-Yang , Wu Wen-Wei
Published: May 2020

Electromigration(EM) has become an important issue due to the revolution of scale-down devices in integrated circuit industry. In this study, we introduce high-density electroplated nanotwins into copper, and the EM rate on surface can be measured through in-situ transmission electron microscope(TEM). Moreover, in-situ experiment also provides real time observation on atomic variation of the surface structure. The EM rate has found to be retarded at the triple points, which is significantly slower than previous researches, and improve the durability of the device. Furthermore, the free surface where a twin intersects is transform to a zigzag surface, consisting of alternating (200)/(111) planes. And Cu atoms were gradually removed along (111) when applying a current with a density of 104 A/cm2.
X-Ray Photoelectron Spectroscopy Estimation of Cobalt Seed Layer Reactivity Toward Air Exposure: A Challenge?
Authors: Etcheberry Arnaud , Lakhdari Amine , Caillard Louis , Suhr Dominique , Thiam Mikailou , Raynal Frederic , Simon Nathalie , Gonçalves Anne-Marie , Mevellec Vincent , Frégnaux Mathieu
Published: May 2020

The impact of the air-exposure of an electroplated cobalt film has been investigated to assess the effect of oxygen interaction on metallic cobalt surface. XPS is used in order to evaluate the Co2p spectra of different time air exposure. We demonstrate that the oxidation start very quickly and then is stabilized toward a limited oxide thickness. Dipping oxidized electrodeposited Co film in two acidic solutions (HCl 1M and Kari© aveni acidic Co chemistry) shows that the oxide dissolution must be considered as a main phenomenon for the seed layer during plating process.
(Invited) Germanium Nanocrystal Luminescence: Spectral and Spatial Variations
Authors: Rowell Nelson L. , Lockwood David J.
Published: May 2020

We have investigated the intense infrared photoluminescence (PL) from several dozen molecular-beam-epitaxy Si1-xGex layer samples. For one sample the PL was imaged with an infrared camera with the emission integrated from 650 to 1000 meV. This sample was a SiGe/Si multiple quantum well (MQW) structure, with 40 Si0.7Ge0.3 layers 7.6 nm thick separated by 20 nm of Si on a Si(001) substrate. For excitation at normal incidence, the PL was brightest at the excitation point, but similarly intense at the sample edge. With focused excitation, the edge emission spot had the same diameter as the emission at the excitation spot. Thus the emission was much more collimated in the MQW waveguide than normally in bulk luminescence. Analysis of the luminescence spectral linewidth was performed to estimate the lateral dimensions of the Ge nanocrystals, values which were compared with plan-view TEM results.
(Invited) Towards Tm2+ in Sialon Thin Films Grown by Sputtering Using the Gradient Deposition
Authors: Bosco Giacomo , van der Kolk Erik
Published: May 2020

The valence stability parameter (EFf), defined as the difference between the charge transfer energy to the host intrinsic Fermi energy, was used as criterion to analyze the capability of different host materials within the SiAlON class to stabilize divalent thulium. Available data on charge transfer energies and optical bandgap values are reviewed for Si3N4, SiO2, AlN, and Al2O3. In addition, new data on thin films, collected by our gradient sputter deposition and characterization method on silicon and aluminum nitrides (Si0.75xAl1-xN), are reported. These data are sufficient to show that, at least in the nitride subsection of the SiAlON class, divalent thulium is not expected to be stable due to the presence of high EFf values. The use of sub-stoichiometric silicon nitride and oxide is also briefly considered.
Thermally Stimulated Evolution of Optical and Structural Properties of Germanium-Doped Alumina Films
Authors: Khomenkova Larysa , Makasheva Kremena , Petrik Peter , Bonafos Caroline , Ratel-Ramond Nicolas , Melnichuk Oleksandr , Melnichuk Lyudmyla , Balberg I. , Gourbilleau Fabrice , Korsunska N.
Published: May 2020

Ge-doped Al2O3 films were deposited on long, non-rotated quarts substrate by magnetron co-sputtering of Ge and Al2O3 space-apart targets. This approach allowed to vary Ge content along the film length in the range 5-85 at.%. Simultaneous annealing treatment of such long samples permitted to investigate the evolution of optical and structural properties of the films with different Ge content. It was observed that all as-deposited films and those annealed at TA=550 °C during 50 min in nitrogen atmosphere were amorphous whatever Ge content. The formation of Ge nanocrystals was observed after treatment at TA=600 °C during 1-15 min. The higher Ge content, the shorter annealing time was required to form Ge nanocrystals. This annealing stimulated also an appearance of photoluminescence in visible-near infrared spectral range. Three specific bands centered at about 590 nm, 620 nm and 700-730 nm were detected. Their relative contribution was depended on Ge content determining the shape and peak position of luminescence spectrum. Two former components were ascribed to the carrier recombination via the defects in Ge oxide shell covered Ge nanocrystals, whereas the latter one was assumed to originate from carrier recombination in amorphous Ge clusters or via defects at Ge-cluster/Al2O3 interface. This statement was supported by the heat treatment of the films at TA=700-800 °C caused significant decrease of Ge content due to Ge out-diffusion from film volume via formation of volatile GeO.
Porous Silica as a Nanotemplate for the Solid State and Liquid Phase Synthesis of Luminescent Carbon Dots
Authors: Vasin A. V. , Kysil D. V. , Sevostianov S. V. , Isaieva O. , Rudko G. Yu. , Yatskiv Roman , El Hamzaoui H. , Capoen B. , Bouazaoui M. , Tertykh V. , Nazarov A. N.
Published: May 2020

Sol-gel derived nanoporous silica ceramics were used as morphological template for solid-state and liquid-phase synthesis of luminescent carbon nanodots. Two kinds of porous silica with specific area of 90 m2/g and 233 m2/g were used. Solid-state process involved immobilization of phenyltrimethoxysilane molecules on the silica surface followed by pyrolysis at temperature in range of 500-600 oC. Evolution of photoluminescence from near UV range into visible spectral range was observed in solid state samples with increase of annealing time and temperature. Liquid-phase procedures were performed by thermolysis of sucrose/dimethylsulfoxide solution. Porous silica was then used for extraction of luminescent carbon nanodots from DMSO and release to water. Solutions of carbon dots demonstrated multiband nature of emission/excitation spectra. The effect of porosity on the spectral properties of emission and excitation is analyzed and discussed.
Switching Dynamics Measurement of Ferroelectric Y-Doped HfO2 M-I-M Capacitor
Authors: Lin YuWei , Mizutani Kazuto , Hoshii Takuya , Wakabayashi Hitoshi , Tsutsui Kazuo , Kakushima Kuniyuki
Published: May 2020

The switching dynamics of ferroelectric Y-doped HfO2 films are evaluated and the thickness or the remnant polarization dependence is shown. Based on data fitting to Kolmogorov-Avrami-Ishibashi (KAI) model, the films have shown a small n-value, a parameter representing the dimension of the domain switching, of 1. This value is in contrast to the commonly observed values of over 2 for Hf0.5Zr0.5O2 films.
Electrical Characterization of Sputter Deposited AlxSc1-XN Thin Films
Authors: Tsai SungLin , Kusafuka Kazuki , Hoshii Takuya , Wakabayashi Hitoshi , Tsutsui Kazuo , Kakushima Kuniyuki
Published: May 2020

Nitride-based materials including AlxSc1-xN (ASN) films have also been proven to show a ferroelectricity with a box-like characteristic recently. In this paper, ASN thin films were deposited by RF sputtering with different metal electrode materials, Al, W, TiN and Ni. Leakage current measurements hardly showed difference among the electrode materials. A Schottky barrier height (SBH) at metal/ASN interface was as small as 0.86 eV, irrespective to the electrode material, suggesting a strong Fermi level pinning (FLP). Capacitance-voltage (CV) measurements revealed ferroelectric-like hysteresis behavior for all the electrode materials.
(Invited) Recent Advances in the Modeling of Strain Relaxation and Dislocation Dynamics in ZnSSe/GaAs (001) Heterostructures
Authors: Ayers John E , Kujofsa Tedi , Raphael Johanna , Islam Md Tanvirul , Wales James , Lindstrom Kevin , Song Yifei
Published: May 2020

In this paper we describe state-of-the-art approaches to the modeling of strain relaxation and dislocation dynamics in ZnSSe/GaAs (001) heterostructures. These are based on the extension of the Dodson and Tsao plastic flow model [B. W. Dodson and J. Y. Tsao, Appl. Phys. Lett., 51, 1325 (1987); Appl. Phys. Lett., 52, 852 (1988)] to include compositional grading and multilayers, dislocation interactions, and differential thermal expansion. Important recent breakthroughs have greatly enhanced the capability of the modeling approach in three respects: i) pinning interactions have been included in graded and multilayered structures for the first time, providing a better description of the limiting strain relaxation as well as the dislocation sidewall gettering; ii) a refined model for dislocation-dislocation interactions including jogging provides a more accurate physical description of compositionally-graded layers and step-graded layers; and iii) inclusion of back-and-forth weaving of dislocations provides a better description of dislocation dynamics in structures containing strain reversals, such as strained-layer superlattices and overshoot graded layers. Here we describe these three key advances and illustrate applications of each to practical heterostructures.
Precipitation of Molybdenum Oxides in Supersaturated Zinc Oxide Thin Films
Authors: Chen Yijia J , Zhu Shen-how , Lin Tien-Chai
Published: May 2020

Zinc oxide thin films saturated with molybdenum were prepared by RF magnetron sputtering process. A surprising finding about the study is the electrical conductivity increases and then decreases with molybdenum sputtering power. Hall measurement study shows that the conductivity decrease is caused by decreased electron concentration. However, the electron mobility increases steadily with increased molybdenum sputtering power in the same range even though the molybdenum incorporation still increases. This is an indication that the electrical conduction no longer occurs through the molybdenum-doped ZnO grains. We conclude that the conduction changes from grains to grain boundaries as molybdenum sputtering power increases. It means molybdenum is precipitated at the grain boundaries and forms conducting channels besides zinc oxide grains. The high mobility conduction channel might be desired for devices using electron transport layers in their structures.
Effect of Sputtering Atmosphere on ZnSnN2 Thin Films Electrical and Optoelectronic Properties
Authors: Bui Thanh Ngoc Kim , Halbwax Mathieu , Vilcot Jean-Pierre
Published: May 2020

ZnSnN2 thin films were produced on glass substrates by co-sputtering Zn and Sn targets at room temperature in a reactive atmosphere of argon, nitrogen and hydrogen. By changing the composition of this atmosphere, the optical and electrical properties of material are changed. The morphology and crystal structure were investigated by using SEM, AFM and X-ray diffraction. The optical band gap ranges from 1.80 eV to 2.13 eV and was deduced from UV-VIS spectroscopy. The n-type carrier concentration was measured between 2.5 x 1017 and 1.0 x 1020 cm-3 and the highest carrier mobility is 2.0 cm2V-1s-1. First photoconductive samples were fabricated and tested under solar simulator. Measurement gave a photocurrent value of 150 mA/cm2. These results are promising ones for the potential application of ZnSnN2 material as a photovoltaic absorber.
Experimental and Modeling Results for Dislocation Sidewall Gettering in ZnSSe/GaAs (001)
Authors: Raphael Johanna , Kujofsa Tedi , Ayers John E
Published: May 2020

Dislocation sidewall gettering (DSG) is an important method for the removal of device-compromising defects from optoelectronic devices such as detectors and light-emitting diodes. DSG involves patterned epitaxy or post-growth patterning and annealing, and allows misfit dislocations to elongate until they are captured by image forces at sidewalls. Despite this physical understanding of the process, practical application of DSG has often been guided by empirical trials due to the scarcity of modeling studies. In this work we apply a detailed model for lattice relaxation and dislocation dynamics to DSG in heteroepitaxial ZnSSe/GaAs (001), considering the effects of thickness, composition, growth temperature, and annealing, and we compare modeling and experimental results for this material system.
(Keynote) Gate-All-Around Nanowire & Nanosheet FETs for Advanced, Ultra-Scaled Technologies
Authors: Veloso Anabela , Matagne Philippe , Jang Doyoung , Huynh-Bao Trong , Chasin Adrian , Simoen Eddy , Eneman Geert , De Keersgieter An , Mertens Hans , Horiguchi Naoto
Published: May 2020

We report on gate-all-around (GAA) vertically stacked lateral nanowires (NW) and nanosheets (NS) FET devices as promising candidates to replace finFETs and help preserve the power, performance, area, and cost (PPAC) logic roadmap for advanced sub-5nm technology nodes. In addition, GAA vertical NW/NS FETs appear particularly attractive for enabling highly dense memory cells such as ultra-scaled MRAMs with lower energy consumption and smaller access latency values. Key fabrication challenges and device features for both types of transistors will be discussed here, together with the possibility to manufacture them on the same wafer by a cost-effective, co-integration scheme to obtain simultaneously a high-performance logic platform and have increased on-chip memory content.
(Keynote) Fully-Depleted SOI Technology for High-Power RF Applications
Authors: Dinh Thanh Viet
Published: May 2020

This paper analyzes the latest development of critical RF devices which are capable of delivering both high RF performance and high-voltage robustness in fully-depleted SOI technology. The unique features of RF measurements and EM simulations for these devices, together with their impact on associated designs of RF applications, are discussed.
Intrinsic Voltage Gain of Stacked GAA Nanosheet MOSFETs Operating at High Temperatures
Authors: Perina Welder Fernandes , Silva Vanessa Cristina Pereira , Martino Joao Antonio , Agopian Paula Ghedini Der , Simoen Eddy , Veloso Anabela
Published: May 2020

In this work, the GAA silicon nanosheet MOSFETs basic parameters are evaluated for different channel lengths at high temperatures. The devices showed a subthreshold swing near the theoretical limit, low temperature variation on threshold voltage (dVTH/dT = -0.4 mV/ºC) and low drain induced barrier lowering (DIBL = 50 mV/V at 200ºC), both for n-type device. The devices achieved an intrinsic voltage gain around 33 dB for the worst case (channel length of 28 nm), showing that this device is a promising technology for the 7 nm node of the MOS roadmap.
(Invited) Post-CMOS Compatible Silicon MEMS Nano-Tactile Sensor for Touch Feeling Discrimination of Materials
Authors: Takao Hidekuni
Published: May 2020

Based on silicon post-CMOS compatible process, we have realized high performance silicon MEMS tactile sensor called “Nano-tactile sensor”, which is comparable to the performance of fingertip sense of touch. In this tactile sensor device, all the mechanical structures are made from single crystalline silicon which is the active layer of SOI wafers. No elastomer/polymer structures are used in the mechanical sensing structure, and softness and elasticity necessary to tactile sensing are realized by silicon micro mechanical structures. In the latest version of our tactile sensors, six contactors with fingerprint-like shape are integrated at a pitch of 500µm to get high spatial resolution tactile images. Each fingerprint-like contactor reproduces vertical motion (by micro roughness) and horizontal motion (by frictional force) of a fingerprint closely under sweeping motion of fingertip in measurement. The performances are enough high to analyze surface touch feelings of “Hair surface condition”, “Skin condition”, and “Touch feeling of various papers and clothes” like human fingertip. Combination of high-resolution tactile sensor and deep neural network is a strong approach to reproduce human fingertip sensation by state-of-the-art device electron device technology.
(Invited) CMOS-MEMS Based Microgravity Sensor and Its Application
Authors: Masu Kazuya , Machida Katsuyuki , Yamane Daisuke , Ito Hiroyuki , Ishihara Noboru , Chang Tso-Fu Mark , Sone Masato , Shigeyama Ryo , Ogata Taiki , Miyake Yoshihiro
Published: May 2020

This paper reviews the feature of newly developed CMOS-MEMS (microelectromechanical systems) and MEMS accelerometers and its application for a diagnosis of Parkinson’s disease. In order to realize micro-G (1G=9.8m/s2) level sensing, we propose and develop capacitive MEMS accelerometers with Au proof mass using the multi-layer metal technology. In order to reduce Brownian noise (BN), which determines the sensitivity of MEMS accelerometer, we utilize Au as a high density proof mass. In addition, we investigate the crystal structure of Au in terms of the device reliability. Furthermore, we demonstrate the validity of applying the MEMS accelerometer for the early-stage diagnosis of Parkinson’s disease. The experimental results regarding the sensor, the material and the diagnosis suggest that our microgravity sensor can pave the new way for the early-stage diagnosis of Parkinson’s disease.
(Keynote) Low Temperature SmartCutTM Process for 3D Integration
Authors: Schwarzenbach Walter , Reboh Shay , Ghorbel Aymen , Gaudin Gweltaz , Besnard Guillaume , Mazen Frédéric , Loup Virginie , Maitrejean Sylvain , Brunet Laurent , Nguyen Bich-Yen , Maleville Christophe
Published: May 2020

To support 3D Sequential integration with a cost-effective layer transfer, SmartCut™ process at low temperature (below 500 °C) is proposed. Excellent SOI & BOX layer thickness uniformities are demonstrated, while layer integrity, electron and hole mobility performances are already compliant with development grade requirements.
Graphitic Nanoporous Carbon Thin Films: Fabrication Method, Structural, Electrical and Gas Sensor Properties
Authors: Slobodian O. M. , Gomeniuk Y. V. , Vasin A. V. , Rusavsky A. V. , Okholin P N , Gudymenko O. Yo. , Khyzhun Oleg Yu , Nikolenko A. , Lytvyn P. , Korchovyy A. , Yatskiv R. , Nazarova Tamara M. , Stepanov V. , Kisyl D. , Nazarov A. N.
Published: May 2020

New method (magnetron plasma enhanced CVD) is suggested to obtain record values of porosity of thin carbon films. Further high temperature annealing results in graphitization of the carbon film and reduction of their resistivity down to 102 Ohm×cm. Plasma treatment in forming gas leads to modification both of a surface and bulk thin nanoporous graphitic film that decreases resistivity of the film, reduces sensor sensitivity to water vapour and enhances sensor sensitivity to ammonia gas.
Readout Circuit Design Using Experimental Data of Line-TFET Devices
Authors: Gonçalez Walter , Rangel Roberto , Martino Joao Antonio , Agopian Paula Ghedini Der
Published: May 2020

By considering the analog characteristics of Line Tunneling Field Effect Transistors (Line-TFETs) that are suitable for small-signal amplification, this paper studies the design of a readout circuit with these devices while making comparisons with conventional MOSFET designs. The results show that the Line-TFET design exhibits high gain and low reading error (51dB open loop gain) while using a simple one-stage amplifier and results in a huge reduction in circuit area by using pseudo feedback resistors that have their differential resistance increased for smaller dimensions, achieving up to 50Gohm in a 120nm x 100nm device. This enables cutoff frequencies below 1Hz while using nanometer devices and smaller capacitors. Moreover, the readout circuit achieves 33nW of power consumption even though the Line-TFET devices are not biased in the subthreshold regime.
Functionalization of Polymeric Nanofilter Biointerface for Small Biomarker Sensing
Authors: Fukuma Toru , Nishitani Shoichi , Sakata Toshiya
Published: May 2020

We propose a polymeric nanofilter biointerface with a multilayer that suppresses nonspecific signals caused by interfering species such as proteins and small biomolecules for potentiometric biosensors. In a previous work, we successfully prevented small biomolecules from reacting with the Au electrode using a polymeric nanofilter with a single polymeric layer, resulting in the suppression of nonspecific signals in an extended-Au-gate field-effect transistor (FET). In this study, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is additionally employed as an antifouling nanofilter layer to suppress the nonspecific adsorption of proteins on the Au gate surface. We precisely graft the polymeric nanofilter on the Au electrode via diazonium chemistry and activators regenerated by electron transfer surface-initiated atom transfer radical polymerization (ARGET SI-ATRP). By impedimetric analysis, we found that the charge transfer resistance (R
CT) of the Au electrode with the PMPC-based nanofilter hardly changes even when human serum albumin (HSA) is added onto the electrode. That is, the PMPC-based nanofilter effectively contributes to the prevention of the nonspecific adsorption of proteins such as HSA.
Demonstration of EDL Modulated FET Biosensors with Impedance Analysis
Authors: Wu Chang-Run , Wang Shin-Li , Chen Po-Hsuan , Chen Jung-Chih , Wang Yu-Lin
Published: May 2020

In this study, the electric double layer (EDL) modulated FET biosensor is demonstrated with impedance analysis. The unique sensor design allow protein to be detectable in high ionic strength solution. The enhanced EDL created by applying higher gate voltage is the key role to modulate the FET, causing the high sensitivity. AC impedance analysis is introduced to demonstrate the capacitance nature in our sensor system. The transduction signal of C-reactive protein (CRP) detection is dominated by imaginary part of impedance. With enhanced EDL and high transconductance of FET, this novel technology allow protein to be detectable in physiological sample without any sample pretreatment.
Identification of Lithium Plating in Lithium-Ion Batteries by Electrical and Optical Methods
Authors: Ringbeck Florian , Rahe Christiane , Fuchs Georg , Sauer Dirk Uwe
Published: May 2020

The detection of lithium plating is a key enabler for the development of fast charging techniques. This work compares different plating detection methods to assess the validity of electrical stripping detection methods. To achieve this, we charged a commercial battery cell under different charging regimes regarding temperature, cooling, current, and maximum voltage. Indicators for plating were collected by electrical stripping measurements as well as optical and laser microscopy measurements on fully charged disassembled cells. The results of the electrical measurements agree with a previous publication by Campbell et al. The disassembled cell shows obvious indications of plating in the form of discolored regions and microscopic indications in the form of dendritic structures on the anodes.
Evaluation of The Electrochemo-Mechanically Induced Stress in All-Solid-State Li-Ion Batteries
Authors: Tian Hong-Kang , Chakraborty Aritra , Talin A. Alec , Eisenlohr Philip , Qi Yue
Published: May 2020

The mechanical degradation of all-solid-state Li-ion batteries (ASSLBs) is expected to be more severe than that in traditional Li-ion batteries with liquid electrolytes due to the additional mechanical constraints imposed by the solid electrolyte on the deformation of electrodes. Cracks and fractures could occur both inside the solid electrolyte (SE) and at the SE/electrode interfconce. A coupled electrochemical-mechanical model was developed and solved by the Finite Element Method (FEM) to evaluate the stress development in ASSLBs. Two sources of volume change were considered, namely the expansion/shrinkage of electrodes due to lithium concentration change and the interphase formation at the SE/electrode interface due to the decomposition of SEs. The most plausible solid electrolyte decomposition reactions and their associated volume change were predicted by density functional theory (DFT) calculations. It was found that the stress associated with a volume change due to solid electrolyte decomposition can be much more significant than that of electrode volumetric changes associated with Li insertion/extraction. This model can be used to design 3D ASSLB architectures to minimize their internal stress generation.
Fast Charging of Li-Ion Cells: Part III. Relaxation Dynamics and Trap-Controlled Lithium Ion Transport
Authors: Shkrob Ilya A. , Rodrigues Marco-Tulio F. , Abraham Daniel P.
Published: May 2020

Fast charging of Li-ion batteries would ease consumer concerns regarding refueling time of electric vehicles. In this series of articles, we are systematically examining the effects of high currents flowing through the cell. Here we consider open-circuit relaxation dynamics for cell voltage and individual electrode potentials after abrupt termination of steady-state charging currents (1-6C) or short current pulses (< 30 s) of either polarity (to 16C). We demonstrate that dispersive kinetics observed after these current perturbations become faster for higher currents applied before the rest period. Our observations indicate that the voltage relaxation behaviors (i) depend on the current during charge, and less so on the state of charge, (ii) display universal stretched-exponential kinetics, (iii) can be induced by a short current pulse, (iv) require a minimum amount of charge transfer during the pulse, and (v) originate mainly from the oxide cathode. Trap controlled Li+ ion transport through a partially disordered oxygen-depleted subsurface layer in the cathode is suggested as a possible origin for the relaxation behavior. The slow multidecadal responses to high currents can cause the nonlinearities observed during rapid charging of the electrochemical cells, reported in Part 2 of this series.
Evidence of structural and functional plasticity occurring within the intracardiac nervous system of spontaneously hypertensive rats
Authors: Ashton Jesse L. , Argent Liam , Smith Joscelin E. G. , Jin Sangjun , Sands Gregory B. , Smaill Bruce H. , Montgomery Johanna M.
Published: May 2020

We have developed intracardiac neuron whole cell recording techniques in atrial preparations from control and spontaneous hypertensive rats. This has enabled the identification of significant synaptic plasticity in the intracardiac nervous system, including enhanced postsynaptic current frequency, increased synaptic terminal density, and altered postsynaptic receptors. This increased synaptic drive together with altered cardiac neuron electrophysiology could increase intracardiac nervous system excitability and contribute to the substrate for atrial arrhythmia in hypertensive heart disease.
Reduced stiffness and augmented traction force in type 2 diabetic coronary microvascular smooth muscle
Authors: McCallinhart Patricia E. , Cho Youjin , Sun Zhe , Ghadiali Samir , Meininger Gerald A. , Trask Aaron J.
Published: May 2020

We show here that a potential causative factor for reduced diabetic coronary microvascular stiffness is the direct reduction in coronary vascular smooth muscle cell stiffness. These cells were also able to generate enhanced traction force, validating previously published computational models. Collectively, these data show that smooth muscle cell stiffness can be a contributor to overall tissue stiffness in the coronary microcirculation, and this may be a novel area of interest for therapeutic targets.
Differential effects of REV-ERBα/β agonism on cardiac gene expression, metabolism, and contractile function in a mouse model of circadian disruption
Authors: Mia Sobuj , Kane Mariame S. , Latimer Mary N. , Reitz Cristine J. , Sonkar Ravi , Benavides Gloria A. , Smith Samuel R. , Frank Stuart J. , Martino Tami A. , Zhang Jianhua , Darley-Usmar Victor M. , Young Martin E.
Published: May 2020

Circadian clocks are composed of more than 10 interconnected transcriptional modulators, all of which have the potential to influence the cardiac transcriptome (and ultimately cardiac processes). Previous studies indicate that cardiomyocyte-specific BMAL1 knockout (CBK) mice exhibit a dysfunctional circadian clock (including decreased REV-ERBα/β expression) in the heart, associated with abnormalities in cardiac mitochondrial function, metabolism, signaling, and contractile function. Here we highlight decreased REV-ERBα/β as a mediator of glycogen synthesis, cardiomyocyte size, interstitial fibrosis, and contractile function abnormalities observed in CBK hearts.
In Vitro and In Vivo Antifungal Activity of Clove (Eugenia caryophyllata) and Pepper (Piper nigrum L.) Essential Oils and Functional Extracts Against Fusarium oxysporum and Aspergillus niger in Tomato (Solanum lycopersicum L.)
Authors: Muñoz Castellanos Laila , Amaya Olivas Nubia , Ayala-Soto Juan , De La O Contreras Carmen Miriam , Zermeño Ortega Miriam , Sandoval Salas Fabiola , Hernández-Ochoa Leon
Published: May 2020

In this study, hydrodistillation was used to obtain essential oils (EOs) from pepper (Piper nigrum L.) and clove (Eugenia caryophyllata) and co-hydrodistillation (addition of fatty acid ethyl esters as extraction co-solvents) was used to obtain functional extracts (FEs). Antifungal activity of EOs and FEs was evaluated by determination of minimum inhibitory concentration (MIC) against Fusarium oxysporum and Aspergillus niger. The results showed that pepper (Piper nigrum) and clove (Eugenia caryophyllata) essential oils and their functional extracts are effective in vitro at concentrations from 400 to 500 ppm after 10 days of culturing. The essential oils and functional extracts were used on tomato fruit samples at three different concentrations: 350, 400, and 450 ppm5. Clove essential oil reduced the growth of Aspergillus niger from 50% to 70% and Fusarium oxysporum to 40%. The functional extracts (FEs) of clove and pepper, mixed with ethyl decanoate (FEs-C10), were the best combination for protecting the tomato fruit in vivo against both phytopathogenic fungi. Gas chromatography-mass spectrometry (GC-MS) was used to identify eugenol as the principal compound in clove oil and limonene, sabinene, and β-caryophyllene in pepper oil.
Breast Cancer Survival and Incidence: 10 Years Cancer Registry Data in the Northwest, Iran
Authors: Dolatkhah Roya , Somi Mohammad Hossein , Jafarabadi Mohammad Asghari , Hosseinalifam Mehrnaz , Sepahi Sepideh , Belalzadeh Mina , Nezamdoust Marzieh , Dastgiri Saeed
Published: May 2020

Background and Aim. Breast cancer is the most frequent cancer in women and the second most common cancer across the globe. The aim of this study was to report the survival data and trend analysis of breast cancer between 2007 and 2016 in a northwest region in Iran. Methods. Data were obtained from East Azerbaijan cancer registry database for the 10-year period between 2007 and 2016. Survival analysis was performed to calculate the breast cancer-specific survival proportions and mortality rates. Joinpoint trend analysis was performed to estimate the incidence trend of the cancer. Results. A total number of 4989 patients were recorded with primary diagnosis of breast cancer. Of them, we collected follow-up data for 1335 (1309 female and 26 male). The 10-year crude mortality rate was 3.34 (per 100,000). The one-, two-, three-, five-, and ten-year breast cancer-specific survival proportions were 0.92 (95% CI 0.91-0.93), 0.88 (95% CI 0.86-0.90), 0.84 (95% CI 0.83-0.86), 0.77 (95% CI 0.74-0.80), and 0.65 (95% CI 0.60-0.70), respectively. Over the study period, the age-standardized incidence rates increased from 21.68 to 36.99 (per 100,000) with an annual percentage change of 5.5 percent. Older individuals and males patients had significantly worse survival, and patients with high-grade tumors had significantly higher risk of mortality. Conclusion. A relatively better survival for breast cancer in East Azerbaijan, Iran, was observed compared to the overall breast cancer-specific survival proportions and mortality rates in the country. However, it is still poor compared to the developed countries indicating that inappropriate treatment modalities might have played a role on this.
Forecasting Volatility with Time-Varying Coefficient Regressions
Authors: Zhu Qifeng , You Miman , Wu Shan
Published: May 2020

We extend the heterogeneous autoregressive- (HAR-) type models by explicitly considering the time variation of coefficients in a Bayesian framework and comprehensively comparing the performances of these time-varying coefficient models and constant coefficient models in forecasting the volatility of the Shanghai Stock Exchange Composite Index (SSEC). The empirical results suggest that time-varying coefficient models do generate more accurate out-of-sample forecasts than the corresponding constant coefficient models. By capturing and studying the time series of time-varying coefficients of the predictors, we find that the coefficients (predictive ability) of heterogeneous volatilities are negatively correlated and the leverage effect is not significant or inverse during certain periods. Portfolio exercises also demonstrate the superiority of time-varying coefficient models.
A Combined Ultrasonic Backscatter Parameter for Bone Status Evaluation in Neonates
Authors: Mao Weiying , Du Yang , Liu Chengcheng , Li Boyi , Ta Dean , Chen Chao , Zhang Rong
Published: May 2020

Metabolic bone disease (MBD) is one of the major complications of prematurity. Ultrasonic backscatter technique has the potential to be a portable and noninvasive method for early diagnosis of MBD. This study firstly applied CAS to neonates, which was defined as a linear combination of the apparent integrated backscatter coefficient (AIB) and spectral centroid shift (SCS). The objective was to evaluate the feasibility of ultrasonic backscatter technique for assessing neonatal bone health using AIB, SCS, and CAS. Ultrasonic backscatter measurements at 3.5 MHz, 5.0 MHz, and 7.5 MHz were performed on a total of 505 newborns within 48 hours after birth. The values of backscatter parameters were calculated and compared among gestational age groups. Correlations between backscatter parameters, gestational age, anthropometric indices, and biochemical markers were analyzed. The optimal predicting models for CAS were determined. The results showed term infants had lower SCS and higher AIB and CAS than preterm infants. Gestational age and anthropometric indices were negatively correlated with SCS (|r| = 0.45 – 0.57, P < 0.001), and positively correlated with AIB (|r| = 0.36 – 0.60, P < 0.001) and CAS (|r| = 0.56 – 0.69, P < 0.001). Biochemical markers yielded weak or nonsignificant correlations with backscatter parameters. CAS had relatively stronger correlations with the neonatal variables than AIB and SCS. At 3.5 MHz and 5.0 MHz, only gestational age (P < 0.001) independently contributed to the measurements of CAS, and could explain up to 40.5% – 44.3% of CAS variation. At 7.5 MHz, the combination of gestational age (P < 0.001), head circumference (P = 0.002), and serum calcium (P = 0.037) explained up to 40.3% of CAS variation. This study suggested ultrasonic backscatter technique was feasible to evaluate neonatal bone status. CAS was a promising parameter to provide more information about bone health than AIB or SCS alone.
Diversity of Soil Filamentous Fungi Influenced by Marine Environment in São Luís, Maranhão, Brazil
Authors: Rodrigues Igor Vinícius Pimentel , Borges Katia Regina Assunção , Custódio Neto da Silva Marcos Antonio , Soares Brandão Nascimento Maria do Desterro , dos Santos Juliano , Santana Azevedo Alexandre , Bezerra Geusa Felipa de Barros
Published: May 2020

Introduction. In recent decades, there has been an intensification of environmental problems, which are becoming increasingly critical and frequent due to population growth. Microorganisms, including soilborne fungi, play an essential role in maintaining and balancing the environment. One of the most impacted ecosystems in São Luís, Maranhão, Brazil, is the Jansen Lagoon State Park, an important tourist spot, which has suffered anthropogenic actions such as the dumping of household waste (sewage) in its body of water. As a consequence, these pollutants can accumulate in the adjacent soil, since the body of water is near this substrate. The objectives were to isolate and identify filamentous fungi from the soil of the Jansen Lagoon State Park. Methods. Monthly soil samples were collected and later processed using the modified suspension technique according to Clark (1965). Results. The isolated genera were Aspergillus, Penicillium, Trichoderma, Absidia, and Fusarium. Aspergillus is the fungal genus of greater dominance in the soil of the Jansen Lagoon State Park. Aspergillus niger was the dominant species (37%), followed by A. tamarii (21.6%). Conclusion. The main isolated fungi from the Jansen Lagoon State Park were Aspergillus niger and Aspergillus tamrii. These fungi can be used as biological markers of pollution and as biodegraders and/or bioremediators to improve the area studied.
Competition Order and Innovation Behaviors of Enterprise in China
Authors: Cui Weijun , Chen Guang , Fu Yu
Published: May 2020

This study addresses the apparent puzzle that China made great progress in mobile phone manufacturing despite weak intellectual property protection. Using the China 2012 Enterprise Surveys Data set of World Bank enterprises survey, we investigated whether competition order mattered for innovation behaviors of enterprise and mainly drew three major conclusions. First, when there are unregistered or informal competitors in the market, enterprises tend to choose innovation to improve the current situation of their own operations, and they may increase the R&D investment. Second, when the unregistered or informal competitors in the market become obstacles to the enterprise, with the rise of disorderly barriers to competition, enterprises will reduce their decision-making of innovation behavior or the intensity of R&D investment. Third, the impartiality degree of court may have a moderating effect on the relationship between competition order and corporate innovation behavior.
Occupational Risks in Occupational Therapy Service Learning: A Single-Site “Fear Factor” Study in South Africa
Authors: Naidoo Deshini , Govender Pragashnie , Naidoo Stephanie Nicole , Ngubane Naledi , Nkosi Zamankosi , Mulla Aziza
Published: May 2020

Background. Service-learning constitutes the main practical component of an undergraduate health profession training programme. However, limited exploration of the potential occupational risks that students face during their service-learning placement is noted in the literature. Aim. This study in South Africa explored occupational risk factors as reported by occupational therapy students whilst engaged in service-learning. Methods. In this explorative qualitative study, purposeful homogenous sampling was used to recruit third and fourth level occupational therapy students who completed a Bachelor of Occupational Therapy degree. Three focus groups were conducted with seventeen students who voluntarily participated. Audio-recorded data were transcribed and analysed thematically using deductive reasoning. Results. Several concerns over potential occupational risks were reported, namely, anxiety over contracting infectious diseases, concerns around musculoskeletal injuries due to manual handling requirements, and inappropriate behaviour of clients, which made the students feel unsafe. Concerns around the implementation of infection control measures, the lack of resources allocated to infection control at some service-learning sites, as well as the coping strategies used during service-learning were highlighted. Conclusion. Varied occupational risk factors during service-learning were reported by students. These insights into the perceived occupational risk factors can be translated into actionable strategies to improve the preparation of health science students for service-learning, including coping skills to deal with the demands of service-learning.