bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electroless Deposition of Cobalt-Tungsten-Boron Films from Glycine Containing Solutions As Barrier Layer Against Cu Diffusion
Authors: Norkus Eugenijus , Sukackienė Zita , Tamasauskaite-Tamasiunaite Loreta , Naujokaitis Arnas , Jasulaitiene Vitalija 
Published: February 2020

Electroless cobalt films have been demonstrated to produce high quality barrier and capping layers for Cu. The best barriers so far include, in addition to the cobalt, refractory metals ions (e.g., W, Mo, or Re), and either phosphorus or boron. Electroless cobalt and its alloys can be used in micro- and nano-technologies, e.g. for microelectro-mechanical systems (MEMS), as well as for ultra large-scale integration (ULSI) technology of integrated cicuits.
In this work we present novel deposition solutions that is used to form cobalt-tungsten-boron films used morpholine borane as reducing agents. The films of cobalt that cointain small amounts of tungsten and boron were deposited by the electroless process. The cobalt-tungsten-boron coatings were deposited on the copper surface using a solutions containing (mol l-1): CoSO4 - 0.1, NH2CH2COOH (glycine) – 0.2, C4H8ONH·BH3 (morpholine borane) – 0.2, Na2WO4 – (0-0.02), C6H8O7 (citric acid) – 0.175. The bath operated at pH 7 and 60 ºC. The thickness of the compact cobalt-tungsten-boron coatings obtained under optimal operating conditions were ca. 0.5 µm. The morphology and strukture of the cobalt alloys were characterized by means of Field Emission Scanning Electron Microscopy. The composition of the cobalt-tungsten-boron films obtained was determined by means of X-ray Photoelectron Spectroscopy using an ESCALAB MKII spektrometer. To obtain depht profiles, the sample were etched in the preparation chamber by ionized argon at a vacuum of 5·10-4 Pa.
The mikrostructure of the coatings changes with the intercorporation of tungsten into the coatings. The particles of cobalt-tungsten-boron films are larger and almost equilateral as compared with the cobalt-boron particles. XPS depth profile investigation does not show any significant diffusion of Cu atoms into cobalt after heat-treatment of the cobalt-tungsten-boron film. This fact confirms that the cobalt-tungsten-boron thin layer, deposited from glycine containing solutions, serves as a perfect diffucion barrier to prevent Cu diffusion.
This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
Decoration of Fiber Structure Co with Pt or Au Nanoparticles for Catalytic Ppurposes
Authors: Zabielaite Ausrine , Antanaviciute Kornelija , Balciunaite Aldona , Tamasauskaite-Tamasiunaite Loreta , Norkus Eugenijus 
Published: February 2020

In the present study the activity of the Co with a fiber structure decorated by Pt or Au nanoparticles (denoted as Pt/Cofiber and Au/Cofiber) was investigated towards the electro-oxidation of hydrazine. At first, Co coating with a fiber structure and the thickness of ~3 µm was electroplated onto the Cu surface. Then, the Pt nanoparticles were deposited on the prepared Cofiber/Cu by its immersion into the 1 mM H2PtCl6 + 0.1 M HCl solution at the temperature of 25 oC for 10-60 s, respectively, whereas Au nanoparticles were deposited on Cofiber/Cu by its immersion into the 1mM HAuCl4 + 0.1 M HCl for 10-300 s. Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Inductively Coupled Plasma Optical Emission Spectroscopy were used for determination of morphology, structure and composition of the prepared catalysts. The electrocatalytic properties of catalysts were evaluated with respect to the electro-oxidation of hydrazine in an alkaline medium by means of cyclic voltammetry and chrono-techniques.
It was found that the Pt loadings were 5, 15 and 29 µg cm–2 in the prepared Pt(Cofiber)/Cu catalysts after the immersion of Cofiber/Cu into the platinum-containing solution for 10, 30 and 60 s, respectively. The Au loadings were 20, 28 and 96 µg
cm–2 in the prepared Au(Cofiber)/Cu catalysts after the immersion of Cofiber/Cu into the gold-containing solution for 10, 60 and 300 s, respectively. The cobalt with a fiber structure decorated with the Pt or Au nanoparticles show enhanced electrocatalytic activity towards the electro-oxidation of hydrazine in an alkaline medium as compared to that of bare Co deposited on the Cu surface.

Acknowledgment

This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
Electrochemical Properties of Ni-TiO2/NiO Nanocomposite in Amine-Containing Solutions at the Elevated Temperature
Authors: Kim Seunghyun , Kim Ji Hyun 
Published: February 2020

For the development of non-precious-metal-based materials for the assorted electrochemical engineering fields as an alternative for precious metals, we report promising potential of Ni-TiO2/NiO nanocomposite which is synthesized by self-catalytic reactions on metallic substrates. Microstructure characterization via TEM shows the well-dispersed TiO2 nanoparticles in Ni alloy matrix.
Electrochemical properties are investigated via linear sweep voltammetry (LSV) in 125, 150, and 175 oC of 15 ppm ethanolamine (ETA) solution (pH25 9.3). LSV were carried out in order to reveal anodic polarization behaviors (Figure 1) to investigate a hydrogen evolution reaction (HER) on catalytic surface.
The results give while Ni/NiO represents electrocatalytic activity until 125 oC, Ni-TiO2/NiO does until 150 oC. This tendency can be explained by the dissolution of NiO species into Ni2+ ions and TiO2 nanoparticles suppress the corrosion of the Ni frame. Therefore, it can be concluded that the embedded noble and solid nanoparticle can enhance electrocatalytic activity even at the elevated temperatures.

Figure 1
Electropolishing of an Fe-Ni-Co Alloy in Acetic Acid-Perchloric Acid Mixture
Authors: Aksu Yasemin , Erdogan Metehan , Demirci Gökhan , Karakaya Ishak 
Published: February 2020

Among Fe-Ni-Co alloys, Kovar (53% Fe-29% Ni-17% Co) designated as ASTM F-15[1], is a well-known glass-sealing alloy. It also is classified as low–expansion alloy [2]. Low expansion is required to avoid internal stresses for applications that involve strong ceramic to metal joining.
One of the most significant problems in vacuum systems is the outgassing which is the liberation of a gas that was dissolved, trapped, frozen or absorbed in a material. To decrease the outgassing rate from the chamber walls, the material should have smooth and passivated surface finish [3]. Electropolishing, one of the finishing methods applied to decrease surface roughness, is appropriate for the systems involving parts of simple and complex geometries. However, there is very limited information on the electropolishing of Kovar alloy in the literature.
Acetic acid (glacial)–perchloric acid (60%) mixture, stated as a cleaning solution before soldering Kovar [4], was used as electropolishing electrolyte in this work. A systematic study was conducted in 5 to 15% perchloric acid containing electrolytes at 25 to 35°C to find the optimum polishing conditions. A two–electrode setup employing Kovar anode and stainless steel cathode was used to perform voltammetric studies to determine low and high levels of current densities. According to linear sweep voltammetry results, shown in Figure 1, 200 to 600 mA/cm2current density range was selected to optimize electropolishing. Experimental route was designed using three parameters (current density, concentration and temperature) and three levels. The duration was kept constant as 5 minutes. Effect of electropolishing duration was determined by utilizing the condition that revealed the lowest roughness in 5 minutes. It was found that, the surface roughness of Kovar samples (having dimensions of 10×25×2 mm), was decreased from 0.21µm to 0.06 µmRa in a 15% perchloric acid containing solution.
ADDIN EN.REFLIST 1. ASTMInternational, Standard Specification for Iron-Nickel-Cobalt Sealing Alloy. 2009.
2. Special-Purpose Nickel Alloys, in ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys. 2000, ASM International. p. 92-101.
3. Tajiri, K., Pit-free electropolishing of aluminum and its application for process chamber. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1998. 16(3): p. 1196.
4. Vianco, P.T., F.M. Hosking, and J.A. Rejent, Solderability Testing of Kovar with 60Sn-40Pb Solder and Organic Fluxes, in 19th International AWS Brazing and Soldering Conference. 1988: New Orleans, LA.

Figure 1
Study of the Influence of the Operational Parameters on the Photo-Electro-Fenton Performance of an Industrial Waste-Water Treatment Prototype
Authors: Robles Irma , Godinez Mora-Tovar Luis Arturo 
Published: February 2020

A design of experiments (DOE) was used to characterize the influence of the operational parameters of an industrial prototype for waste-water treatment that was designed and built to operate using the Photo-Electro-Fenton technology. Since the approach under study is based on the photo-assisted Fenton reaction, which in turn is based on the production of hydroxyl radical species via electro-generated hydrogen peroxide (H2O2) and iron ions (Fe2+), the reaction was carried out in a prototype conceived in two reactor chambers. While in the first chamber hydrogen peroxide (H2O2) is produced via oxygen reduction using carbon cloth electrodes, the aqueous solution passes to a second chamber containing an iron-loaded resin in which a UV lamp promotes not only the oxidant species production but also iron reduction.
The performance of the industrial prototype was followed by the absorbance decrease of a commercial dye aqueous solution ( (4-(2-Hydroxy-1-naphthylazo) benzene sulfonic acid, sodium salt, ≥98.0%) considering the applied current, the amount of iron-loaded resin, the flow rate and the pH as the operational variables to be characterized and eventually optimized for the operation of the prototype. In this way, a 24 factorial design was considered with two levels for each variable, central points and duplicate and randomized experiments. Variable interactions from the DOE were assessed using variance analysis and parameter estimation (ANOVA) using the statistical software JMP 7.0.2, SAS Institute Incorporated. The results revealed that the interactions for which the Prob >ltl being 0.05 or less are those corresponding to pH, resin and the pH-current-resin interaction parameters. From this information and the corresponding analysis it was possible to obtain an empirical equation that describes the reactor´s performance, along with a series of surface response curves that provide information on the relationship of the different operational variables that control the generation of oxidant species and the performance of the prototype under study.
Nickel and Gold Coatings of Germanium and Kovar Substrates
Authors: Karakaya Ishak , Cetin Yasin , Demirci Gökhan , Erdogan Metehan 
Published: February 2020

The integration of germanium to other materials such as Kovar®(registered trademark of Carpenter Technology Corporation), an Fe-Ni-Co alloy, by soldering requires a surface preparation due to poor wetting characteristics of germanium. Coating (metallization) by successive electroplating of 3 mm wide nickel and gold frames well adhered to the outer edge of a circular germanium window and kovar body was applied to attain successful joining of germanium to kovar.
Surface cleaning of parts to be joined or plated plays an important role in the quality of the depositions. HF and HCl solutions were used for germanium surface cleaning and the results showed that HF solution was more effective than HCl in terms of removing oxide capability. The desired small grain sized solderable nickel layer was achieved by pulse plating from Watts solution. Likewise, non-porous very thin gold was deposited by pulse plating again and it prevented the diffusion of oxygen to nickel and diffusion of nickel to the free surface. Characterization of the coatings were performed in terms of microstructure, roughness and elemental analysis by scanning electron microscopy (SEM), white light interferometry and x-ray photoelectron spectroscopy (XPS), respectively.
(Invited) Engineering Interfaces for Added Functionality of Nanoelectronics
Authors: Hacker Christina A. , Pookpanratana Sujitra , Jang Hyuk-Jae , Richter Curt A. 
Published: February 2020

Future electronic components will be vastly different in response to two critical technical drivers; the increasing complexity to make smaller, faster high performance components and the “electronics everywhere” phenomena requiring portable, low power, niche roles of electronic components. New materials, devices, and architectures are actively being explored to meet these demands. A common theme among these approaches is the need for fundamental innovations and understanding of electronic processes at interfaces. I will describe advances made to manipulate and measure organic and molecular interfaces at the nanometer scale and the impact on the resulting electronic performance. In particular, I will focus on the measurement advances made in molecular electronics, highlighting our understanding of the science and characterization of the critical buried interfaces. This talk will contain two illustrative case studies demonstrating the impact of interface engineering on charge trapping memory devices and spin-based paradigms.
Organic molecules are advantageous for trapped charge memory devices due to their small size, discrete nature, and tunability. Moreover, because each molecule can trap one (and sometimes more) charges, they enable very large trapped charge densities. I will describe a series of advances in creating and characterizing molecular memory devices incorporating a novel ruthenium based redox-active molecule as the charge storage layer.(1)
Spin-based paradigms are increasingly important for future electronics. Of special interest is the manipulation of spin in organic materials. I will describe a series of advances that examine the impact of organic monolayers on the ferromagnetic cobalt and cobalt oxide interfaces and the role interface engineering can play in organic spintronics.(2,3)

1.
“Non-volatile memory devices with redox-active diruthenium molecular compound” S. Pookpanratana, H. Zhu, E. G. Bittle, S. Natoli, T. Ren, D. J. Gundlach, C. A. Richter, Q. Li, and C. A. Hacker J. Phys. Chem.: Condens. Matter, a special issue on “Molecular functionalization of surfaces for device applications” (invited) Oct 2015 accepted

2.
“Modifying spin injection characteristics of Co/Alq3 system by using a molecular self-assembled monolayer”, Hyuk-Jae Jang, J.-S Lee, S. J. Pookpanratana, I. C. Tran, C. A. Hacker, and C. A. Richter, J. Phys. Chem. C 119, 12949 (2015)

3.

“Self-Assembled Monolayers Impact Cobalt Interfacial Structure in NanoElectronic Junctions”

S. Pookpanratana, L. K. Lydecker, C. A. Richter, and C. A. Hacker,
J. Phys. Chem. C, 119(12), 6687-6695 (Mar 2105)
(Invited) Challenges and Solutions for Future Internet-of-Things Semiconductor Technologies
Authors: Schaeffer Jamie K. 
Published: February 2020

Emerging IoT edge-node applications demand new capabilities from semiconductor technologies including unparalleled energy efficiency, reduced package form factor via increased integration, wireless connectivity across a range of low-power wireless protocols, embedded memory for operating systems with smaller footprint and longer battery life, and low cost. This talk will detail the salient features of 22FDXTM technology, the industry’s first 22nm fully-depleted silicon-on-insulator technology, which give designers the tools to satisfy these challenging requirements.
22FDXTM has capabilities to meet the low-static leakage requirements of edge-node MCUs with low duty-cycles and low-static leakage and the performance and low active power requirements of wearable application processors. This is accomplished via a next generation FDSOI transistor architecture, a novel body-biasing capability to dynamically adjust threshold voltages, and a wide-range of Vt options to achieve over 50% total power reduction compared to 28nm and device leakages as low as 1pA/um. To meet the low-cost requirements of IoT, 22FDXTM was architected to minimize costly double patterning steps while maximizing the overall die shrink. Over 40% area reduction relative to 28nm is observed in an ARM A9 Neon core. In addition, the overall BoM and package form factors can be reduced to lower system costs by integrating RF functionality. To satisfy the wireless connectivity requirements, 22FDX provides an IP offering that satisfies a range of low-power wireless protocols such as WiFi, Bluetooth®, and ZigBeeTM and interface network IPs useful for IoT applications. Finally, next generation embedded memories, such as MRAM, could be an energy efficient solution that will provide advances to system designs.
22FDXTM is the right solution to meet the requirements of emerging IoT applications.
Dark Current Suppression of Germanium Photodiode Using Metal-Interlayer-Semiconductor-Metal Structure with TiO2 interlayer
Authors: Zang Hwan-Jun , Yu Hyun-Yong 
Published: February 2020

Germanium (Ge) photodetectors (PDs) are promising optoelectronics device for advanced Si photonics and optical interconnection due to excellent absorption property, near-infrared wavelengths, and process compatibility with Si-based complementary metal-oxide-semiconductor (CMOS). Ge metal-semiconductor-metal (MSM) PDs have many advantages over Ge PIN PDs in terms of low capacitance, high bandwidth, and process simplicity. However, Ge MSM PDs have large dark current because of a low hole barrier height induced by severe Fermi-level pinning between the metal and Ge, which results in poor sensitivity and large power consumption of PDs.
In this work, the dark current of Ge MSM PD was tremendously reduced by introducing asymmetric metal-interlayer-semiconductor-metal (MISM) structure [Fig. 1]. As shown in Fig 2, a thin TiO2 layer was selected as the interlayer to reduce hole dark current by enhancing the hole Schottky barrier and the proposed structure can collect the photo current efficiently due to almost zero conduction band offset between TiO2 and Ge.
Low p-type Ge wafer was used to minimize bulk defect current. To form MISM structure, TiO2 interlayer was deposited by atomic layer deposition (ALD) system at process temperature of 250 °C. To increase responsivity, finger-type PD was used with 10 um finger spacing and 10 um finger width. Metal-semiconductor (MS) contact region is defined by e-beam lithography and etched by 6:1 buffered HF, then metal-interlayer-semiconductor (MIS) contact region is defined by e-beam lithography. Cu contact was formed by e-beam evaporation and lift off process.
As a result, MISM structure exhibits tremendous dark current reduction by approximately 4,000 times at a bias voltage of 1 V. The dark current reduces as the TiO2 thickness increases as shown in Fig. 3. In case of 1 nm-thick TiO2 interlayer the dark current is hardly reduced compared to symmetric MSM structure because most of holes can flow through 1 nm-thick TiO2 interlayer by tunneling. The hole dark current from the metal side diminishes as TiO2 thickness increases because hole tunneling probability decreases. The dark current with 3 nm-thick and 5 nm-thick TiO2 is reduced by 64 times and 3,970 times at 1 V, respectively, from symmetric MSM structure. As shown in Fig. 4, photo I-V measurement was carried out on asymmetric Ge MISM PD with 5 nm-thick TiO2 interlayer with collimated infrared laser (λ=1.55 um). Measured photo current value was 0.2 mA and it was saturated at 0.6 V, and the sensitivity of the PD was 24.52 at 1 V.
In summary, we tremendously suppress dark current by approximately 4,000 times at 1 V using MISM structure. TiO2 interlayer of asymmetric MISM structure efficiently decrease hole dark current, and this structure can be promising structure for dark-current suppression in Ge MSM PD.

Figure 1
Metal Oxide Nanofiber Calcination Studied By Environmental TEM
Authors: Zhang Wenjing , Simonsen Søren Bredmose 
Published: February 2020

Environmental transmission electron microscopy (ETEM) has proven to be a powerful method for studying nano-scaled changes in catalyst materials during exposure to reactive gasses and elevated temperatures [1-3]. In this work, we use ETEM to observe the structural dynamics of electrospun nanofibers during calcination, i.e. while elevating the temperature in the presence of O2. The ETEM movies show nanofiber shrinkage due to polymer oxidation followed by formation, coarsening and sintering of oxide nano-crystals in the fiber. The results show that a nanofiber can be directly transformed to a nanotube or to a nano-pearl string by controlling the calcination temperature.
Electrospinning is a powerful, efficient and cost-effective method to produce one-dimensional (1D) materials [4]. Combined with sol-gel chemistry and calcination, electrospinning has been used to produce a variety of 1D metal oxide nanomaterials that bring remarkable performance enhancement in many energy devices. (e.g. lithium ion batteries, solid oxide fuel cells). The perovskite lanthanum strontium cobalt oxide (LSC), which has been intensively studied for electrochemical devices, is synthesized in this work.
A Titan 80-300 (FEI) transmission electron microscope (TEM) equipped with at differential pumping system allowing for exposure to the specimen of a few mbar of a reactive gas was used. TEM images were recorded while exposing the fibres to 2 mbar of O2 and ramping the temperature from room temperature to 900 °C by 5 °C/min. Thermal analysis was performed at the same oxygen partial pressure balanced in N2 and same ramping rate to link structural dynamics with polymer oxidation and decomposition of the precursers.
[1] S.B. Simonsen, I. Chorkendorff, S. Dahl, M. Skoglundh, S. Helveg, “Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM”, Surf. Sci. Available online, doi:10.1016/j.susc.2015.11.003
[2] S.B. Simonsen, K. Agersted, K.V. Hansen, T. Jacobsen, J.B. Wagner, T.W. Hansen, L.T. Kuhn, “Environmental TEM study of the dynamic nanoscaled morphology of NiO/YSZ during reduction”, Appl. Catal. A:gen 489 (2015) 147
[3] S.B. Simonsen, S. Dahl, E. Johnson, S. Helveg, “Direct Observations of Catalytic Soot Oxidation on a Nano-Scale using Environmental Transmission Electron Microscopy”, SAE Int. J. Mater. Manuf. 1 (2009) 199
[4] W. Zhang, P.N. Pintauro. “High Performance Nanofiber Fuel Cell Electrodes”. ChemSusChem, 4 (2011) 1753

Figure 1
First-Principles Investigation of the Surface Reactivity and Electronic Property of Dopant-Promoted SrTiO3 Catalysts for SOFC Anode Application
Authors: Ham Hyung Chul , Kim Hee Su , Yoon Sung-Pil , Han Jonghee , Nam Suk Woo 
Published: February 2020

The strontium titanium oxide (SrTiO3) has received much attention as an alternative anode material for solid oxide fuel cell (SOFC) owing to its high phase stability and sulfur/carbon resistance in typical SOFC anode operating conditions. However, SrTiO3 has exhibited the low electronic/ionic conductivity and poor electro-catalytic activity toward fuel oxidation, leading to the high overpotential of SOFC. Therefore, it is very imperative to develop highly conductive and active SrTiO3 – based anode catalysts. In this work, we will present some recent density functional theory (DFT)+U calculation results we have on the role of dopants in enhancing the electronic/ionic conductivity and catalytic reactivity of SrTiO3–based catalysts: that is, (1) the origin of improved electronic/ionic conductivity in yttrium(Y)-doped SrTiO3 (2) mechanism of H2 oxidation on the surface of yttrium(Y)-doped SrTiO3 (3) Role of dopant(M) in enhancing H2 oxidation in Sr1-xYxTi1-yMyO3 . This work hints the importance of knowing how to properly tailor the surface reactivity of oxide-based anode materials for achieving wanted electro-catalytic activity for SOFC application.