bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electroless Copper Deposition Using Complexed Copper(II) Ion As Catalyst for Printed Circuit Board Fabrication
Authors: Dow Wei-Ping , Chuang Yu-Chien 
Published: February 2020

Electroless (ELS) copper plating process has been commonly used for printed circuit board (PCB) metallization. The traditional ELS copper plating process uses tin/palladium colloid or complexed palladium ion as catalysts for ELS copper deposition. But the price of palladium catalyst is much higher than that of gold. Herein, we use complexed copper(II) ion to replace the palladium catalyst in order to greatly reduce the process cost but maintain the performance and the reliability of the complexed copper(II) ion as good as palladium. The synthesis process of the complexed copper ion is simple and its cost, which compared with palladium, is cheap. Especially, they have no oxidation issue because they are not metallic copper nanoparticles but copper(II) ions. Before ELS copper plating, the grafted copper(II) ion that is chemically adsorbed onto the substrate surface is reduced to copper atom, so they can catalyze ELS copper deposition. In this work, we optimize the experimental parameters such as operating temperature, reaction time, copper ion concentration and the pH of the plating solution.
After ELS plating process, the backlight test of through holes (THs) of a PCB and the morphology of the ELS copper deposited onto the sidewalls of the THs are evaluated by optical microscope (OM) and scanning electron microscope (SEM), respectively. The thermal reliability of the ELS copper deposition catalyzed by the grafted copper catalyst was examined after copper electroplating using thermal shock in a tin bath at 288℃ for ten seconds and repeated it for 5 times. Results show that it can pass the thermal shock test. Therefore, the application of complexed copper(II) ion as the catalyst of ELS copper plating is expected to replace the expensive palladium for PCB fabrication.
Conductivity Modification of Reduced Graphene Oxide (rGO)
Authors: Lee Yu-Guan , Dow Wei-Ping 
Published: February 2020

In the traditional circuit board metallization process, the electroless plating process is the most common, but it contains precious metals (such as palladium catalyst), formaldehyde and chelating agents which can cause a serious environmental problem. However, the direct reduction process of graphene oxide (GO) does not include the toxic as mentioned above. In additionally, reduced GO (rGO) can be regarded as a direct plating process (i.e., without electroless deposition before copper electroplating) is simpler than electroless plating process and can replace the electroless plating process to achieve a green metallization process.
Although rGO is a good electric conductor, copper is difficult directionally deposited on it due to its p-electron characteristics, which transfers only in X-Y two-dimensions. Therefore, when rGO is electroplated in a copper electroplating solution, the deposited copper crawls initially from the cathodic terminal and then fully cover the rGO-coated substrate if the surface area of the substrate is large.
In this work, we propose an approach to enhance the conductivity of rGO in Z-direction, so that rGO will have three-dimensional conductivity to meet the industrial requirement.
(Invited) CdTe/Si-Roic Staced X-Ray Imaging Sensor
Authors: Aoki Toru , Takagi Katsuyuki , Takagi Toshiyuki , Kase Hiroki , Koike Akifumi 
Published: February 2020

CdTe photon-counting X-ray image sensor with charge-counting readout IC was developed for high quality X-ray imaging. CdTe is one of the good material for X-ray imaging, because it has i) high sensitivity for X-rays by high atomic number (Average 50), ii) room temperature operation with low thermal noise by large band-gap (1.44eV) , and iii) direct conversion from X-ray photon to electron-hole pair (charge). CdTe also has electron mobility (1,100cm2/V/s) and large ut. It is very good properties for X-ray sensor, and it can be processed by using laser processes and some semiconductor post processes.
It is very difficult to make integrated circuit on CdTe wafer, however, we shold stack Si-readout IC and CdTe multi-pixel sensor chip. In this paper, we use sliver paste based bumping for this stack connection. We developed new readout IC, and report in this paper.
A direct charge conversion LSI (Si readout IC) for photon counting X-ray imaging sensor has been fabricated by TSMC 0.18um CMOS process. This LSI is designed to prove a behavior of the direct charge conversion architecture based on charge injection [1] for photon counting with energy information. The LSI has charge-to-digital convertors (QDC) used to read out a charge generated by an X-ray detector such as CdTe and digitize energy information of the source X-ray photon. The QDC realizes 15 energy windows within 200 keV and the LSI provides two 12-bit memories to output two images with differential energy information simultaneously. The LSI has 1600 QDCs and its pixel pitch is 80um. Analogue behaviors of the QDC, characteristics of energy discrimination and a capability to take X-ray/gamma-ray images have been tested. As the results, a desired gain and good linearity are equipped on the QDC, spectra of 241Am and 57Co can be discriminated, and differences between with and without a material have been shown as image. We demonstrate X-ray penetrate image and report in this paper.
References: [1] K. Takagi, et al., Sensors and Materials, Vol. 30, No. 7 (2018) 1611–1616
Fig.1. Direct charge conversion LSI with pixilated CdTe detector.

Figure 1
Advancements in High Indium Content Alinn Grown Via Metal Modulated Epitaxy and Application Towards Polar/Non-Polar Optical Devices
Authors: Engel Zachary , Clinton Evan A. , Matthews Christopher M. , Doolittle W. Alan 
Published: February 2020

AlInN has been a topic of recent study due to its unique property among III-nitrides of lattice matching to GaN at a composition of 18% indium, making it a strong candidate for power electronic and optoelectronic applications. A widely unexplored area is the application of AlInN towards visible/Near-IR optical devices. AlInN has a tunable bandgap, spanning the infrared to ultraviolet range, of 0.7 to 6.1eV. At a composition of about 70% indium AlInN has a perfect bandgap, 1.7eV, for tandem solar cells with silicon and for various optical communications applications. Challenges exist with the growth of AlInN as a result of the large lattice parameter mismatch and differences in growth regimes between the two binary components. At the low temperatures required for the growth of AlInN the aluminum adatoms have a low mobility, often leading to lateral phase separation in the film. Metal Modulated Epitaxy (MME) offers a good solution to the growth issues of AlInN. This flux modulated technique allows for growth under metal rich conditions, increasing surface diffusion lengths of the Aluminum while limiting droplet formation and terminating in a dry surface suitable for devices.
For comparison ~100 nm thick high indium content AlInN samples were grown using nitrogen rich (0.8 III/V ratio) MBE and MME using a III/V ratio of 1.3 with a dose designed to prevent surface segregation (details supplied at the conference). Both films were grown cold at 375 degrees C to limit phase separation The MME sample showed improvement over the MBE sample in crystal quality and surface roughness, with the XRD (0002) reflection FWHM improving from 783 arcsec to 184 arcsec, the XRD (10-15) reflection FWHM improving from 2456 arcsec to 1421 arcsec, and the AFM surface roughness improving from 1.52nm rms to 0.882nm rms between the MBE and MME samples respectively. The carrier concentrations of both samples were found to be about 1E19 cm-3 via hall measurement implying that like InN, In-rich AlInN may suffer from excessive residual electron concentrations and/or surface fermi-level pinning. Optical measurements will be presented at the conference.
The same MME growth conditions were used to grow 100nm of indium rich AlInN directly on a (111) p-silicon substrate. Simple indium contacts were used to contact the Si and AlInN. Vertical conduction and rectification between the silicon and AlInN layers were observed in this large area (~0.25x0.25 cm2) device. Understanding of the limitations of and physics governing this promising vertical polar/non-polar heterojunction will be given at the conference. Additionally, results from various growth conditions will be detailed.

Figure 1
(Invited) Recent Advances in III-Nitride Devices Using Ultrawide Bandgap AlxGa1-Xn Active Layers
Authors: Khan Asif 
Published: February 2020

III-Nitride devices with high-Al AlxGa1-xN (x>0.4) active layers have the potential of addressing several key application areas. For these high Al-compositions the direct bandgap leads to a cut-off wavelength<290 nm which makes the material ideal for solar blind detectors. Similarly, AlxGa1-xN (x>0.4) multiple quantum wells (MQWs) are used in the active region of the deep ultraviolet (DUV) light emitting diodes. More recently, to take advantage of the higher breakdown field for high voltage devices, several researchers including us have explored Heterojunction Field-Effect Transistors (HFETs) and metal-oxide-semiconductor (MOS) HFETs with high-Al AlxGa1-xN (x>0.4) channel layers.
Currently nearly all the (UWBG) AlGaN devices are fabricated on 3-5 µm thick MOCVD grown high quality AlN/sapphire templates. This choice is dictated by the deep UV optical transparency, the easy availability and the low-cost of sapphire. Increasing the AlN template thickness to larger than 5 µm leads to stress related cracking. The low thermal conductivity of sapphire and this AlN growth thickness limitation leads to device performance limitations especially for high power operation. To avoid this, recently using a pulsed MOCVD approach, we have for the first time succeeded in growing 16 µm thick, crack-free, low-defect AlN template layers on basal plane sapphire substrates. These were then used to deposit epitaxial structures for the AlGaN channel HFET/MOSHFETs. In this presentation we will present studies to establish the role that the high conductivity thick AlN buffers play in improving the devices’ electrical and thermal performance.
Recently we have also for the first time conducted optical waveguiding studies at UVC wavelengths. For these studies we fabricated monolithically integrated UVC LEDs, detectors and waveguides on an AlN/sapphire template platform. Optical attenuation coefficient as low as 4.8 cm-1 was measured for Al0.5Ga0.5N waveguide with an AlN clad layer. Details of our integrated device fabrication and optical losses measurements scheme will also be discussed.
Acknowledgement: This work was partially supported by Defense Advanced Research Projects Agency, Army Research Office and Office of Naval Research (Monitors: Dr. M. Gerhold. Dr. Paul Maki and Dr. Lynn Petersen).
(Invited) Heterogeneous Integration of III-V Semiconductors for Imaging and High-Speed Communication
Authors: Wood Michael G 
Published: February 2020

Heterogenous integration of III-V compound semiconductors with Si circuitry is an enabling technology for applications including high-bandwidth communications [1], focal plane arrays [2] and concentrating solar cells [3, 4]. Typical integration schemes include low temperature flip-chip bonding using indium bump bonds along with epoxy underfill and may include the integration of micro-optics for collimation and focusing.
In this talk, I will discuss previous and ongoing compound semiconductor heterogenous integration efforts at Sandia National Laboratories and the challenges involved in forming high-yield devices. Specific programs to be discussed include the ARPA-E MOSAIC solar concentrator (Fig. 1), infrared focal plan arrays (Fig. 2), and the recently-awarded DARPA PIPES ultra-low-energy-per-bit photonic transceiver.
References

Ciftcioglu, et al, “3-D integrated heterogenous intra-chip free-space optical interconnect,” Opt. Express, vol. 20 2012.

W. Peters, et al., “Resonant ultrathin infrared detectors enabling high quantum efficiency,” IEEE RAPID, 2018.

Li, et al., “Wafer integrated micro-scale concentrating photovoltaics,” Prog. Photovoltaics, vol. 26, 2018.

H. Jared, et al., “Integration of wafer-level solar cells and micro-optic concentrators for micro-scale concentrating photovoltaics,” ASPE Annual Meeting, 2017.

Acknowledgment
This work was supported in part by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Figure 1
Electrochemical Energy Storage Properties of Hydrogen Titanates As a Function of Interlayer Structural Protonation
Authors: Fleischmann Simon , Augustyn Veronica 
Published: February 2020

Electrochemical energy storage devices that offer a combined high energy and power are necessary to meet the demand for future mobile applications. Electrode materials that lead to pseudocapacitive charge storage are of particular interest as they enable Faradaic charge transfer at high rates. This behavior is observed when redox processes are not kinetically limited by the solid-state diffusion of reacting ionic species. Pseudocapacitance has mostly been introduced to transition metal oxides by nanostructuring, thereby increasing the electrode-electrolyte interface and reducing diffusion distances.1 Besides often costly synthesis procedures, the materials can show a low density and are hard to integrate in macroscopic electrode structures. A new approach to transition from battery-like to pseudocapacitive charge storage behavior is the use of layered metal oxides with interlayer molecules like structural water.2

Hydrogen titanates (HTO) can be obtained by a proton exchange reaction of sodium titanate in acidic solution. Monoclinic H2Ti3O7 consists of layers of edge-sharing TiO6 octahedra with hydrogen positioned in the interlayer. Upon heating, the interlayer deprotonates over three discrete steps with the intermediate phases H2Ti6O13 and H2Ti12O25, before forming TiO2(B) (Fig. 1).3 The intermediate phases exhibit reduced numbers of hydrogen atoms in the interlayer. This designates HTO as an ideal model system to study the influence of interlayer structural protonation on the electrochemical intercalation properties.
In this study, we synthesized HTO in different states of reduced interlayer structural protonation by thermal annealing and confirmed the compositions by matching the associated mass loss to the release of 0.5 and 0.75 H2O per H2Ti3O7, respectively. The materials were employed as hosts for proton intercalation in acidic electrolyte. Our results suggest a strong correlation between protonation state of the HTO interlayer and proton storage capacity, with fully protonated H2Ti3O7 offering the highest proton intercalation capacity. We will discuss the influence of interlayer proton mobility on the charge storage properties and correlate the crystal structure changes of the materials with the intercalation process.

Augustyn, V., Simon, P. & Dunn, B. Pseudocapacitive Oxide Materials for High-Rate Electrochemical Energy Storage. Energy Environ. Sci.
7, 1597–1614 (2014).

Mitchell, J. B., Lo, W. C., Genc, A., LeBeau, J. & Augustyn, V. Transition from battery to pseudocapacitor behavior via structural water in tungsten oxide. Chem. Mater.
29, 3928–3937 (2017).

Morgado, E. et al. Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: A comparison study between nanostructured and bulk materials. Nanotechnology
18, 81–93 (2007).

Figure 1
Gravimetric and Volumetric Changes of Carbon Electrodes in Electrochemical Capacitors with Aqueous Electrolytes
Authors: Platek Anetta , Menzel Jakub , Bujewska Paulina , Frackowiak Elzbieta , Fic Krzysztof 
Published: February 2020

Ionic fluxes at carbon electrode/electrolyte interface have been already well described for organic medium. This description allowed for comprehensive understanding of the phenomena occuring during electrochemical capacitor operation.
However, the processes on-going in aqueous electrolytes still need to be investigated, since several accompanying phenomena (eg. hydration, corrosion) might occur in this medium.
Our attention is primarily focused on the performance of carbon electrodes operating with pH-neutral aqueous electrolytes, allowing a relatively high capacitor voltage to be reached. Apart from typical capacitive storage, our interest is focused also on hybrid mechanisms, delivered by application of redox-active electrolytes, based on iodides or pseudohalides.
This paper will provide the insights into the ionic fluxes at the electrode/electrolyte interface, monitored by Quartz Crystal Electrochemical Microbalance, Scanning Electrochemical Microscope and Dilatometry techniques.
Preliminary results indicate that the situation at the interface is somehow different than one might expect. For instance, the changes for positive and negative electrode are significantly different, although from electrochemical point of view they appear to follow the conventional cation/anion adsorption manner. In the case of redox-active electriolytes, the situation is even more complicated.
This paper will provide the results from three different techniques - of different modus operandi but allowing for complementary observations and conclusions. Finally, the goal of this work is to understand and identify the phenomena at the interface, mostly in order to prevent the parasitic or detrimental processes and prolong the capacitor lifetime.
Effect of Time, Temperature and Potential on Pre-Conditioning of Supercapacitors
Authors: Roberts Alexander John 
Published: February 2020

One unique property of supercapacitors relative to other energy storage devices is their exceptional lifetime, often reported in commercial devices as being over 1 million cycles. This cycle life is most often accompanied with a lifetime relating to a float at maximum voltage for a time of 1000 (or more) hours at a particular temperature, which gives a more practical indication of lifetime in terms of both time to assess and real life application. The end of life for such devices is taken as the point where the capacitance has decreased by 20% and/or the ESR has increased by 100%.
In the early stages of use for a supercapacitor, a significant drop in capacitance and an accompanying increase in ESR, along with an increased level of gas generation are observed, the result of which would be a reduced lifetime by the conditions defined above. In order to maximise the lifetime and performance of supercapacitors, this early stage is taken care of through a pre-conditioning or ‘burn in’ stage during manufacture.
The causes of the early stage issues mentioned are varied and include decomposition of carbon surface functional groups, solvent splitting (electrochemical decomposition, hydrogen and oxygen evolution reactions including decomposition of trace water) with gas evolution and current collector corrosion[1,2]. The typical burn-in procedure requires the cells to be held at a specific potential and temperature for an extended period of time, during which the capacitance fade, ESR increase and gas generation plateau, allowing the device to then exhibit excellent lifetime characteristics. Whilst the need for this step is clear, it is also costly and can be time consuming, requiring significant Capex and energy costs and also tying up significant inventory during the manufacturing process. Improvements and greater understanding of this process presents clear benefits to the manufacturing process and cost reductions.
In this work, the burn-in process has been investigated at various scales, from coin cells through to 100F pouch cells, with differences in the requirements as the cell size increases discussed. Coin cells and small format pouch cells (70x50mm) have been constructed with YP50-F (Kuraray, Japan) activated carbon electrodes and TEABF4 in acetonitrile electrolyte and have been conditioned at 25oC and floating at 2.7V for 72 hours to ensure a lifetime of over 1000 hours. The temperature and potential of the burn-in has then been varied to shorten the process time and also reduce the total electrical energy required to achieve the same lifetime of device in terms of capacitance and ESR. Furthermore, the effect of water content of the electrolyte on the performance and burn-in process has been investigated.
[1] S. Phadke, S. Amara and M. Anouti, Chem Phys Chem., 18, 2364, 2017
[2] M. He, K. Fic, E. Frackowaik, P. Novak and E. J. Berg, Energy Environ. Sci., 9, 623, 2016
(Invited) Nanoarray Electrodes for High-Rate Thin-Film Batteries
Authors: Fan Hong Jin 
Published: February 2020

Nanoarray electrodes are particularly investigated for power source in microelectronics, which requires high rates, high areal capacity/capacitance and long cycle stability. When the battery electrode materials are designed into nanostructures (e.g., 1D array, 2D nanosheets), the pseudocapacitive effect may become dominating and can boost the power performance. In addition, choosing layered materials with single-phase solid-solution reaction with metal ions is also useful to enhancing the fast charging capability. Our group has been actively working on array-type nanomaterials that are grown directly on conductive substrates as the electrodes of metal-ion batteries. In this talk, I will present the following:
(1) demonstration of vanadium based intercalation-type cathode (e.g., V2O5, NVOPF) and tin based alloy-type anodes in Na-ion storage. Zn-ion batteries based on ZOV cathode and 3D Zn anode with high cyclic stability will also be discussed. These examples demonstrate effectiveness of nanostructure design to boost specific power (i.e., maintaining decent capacity at high discharge currents).
(2) hybrid capacitors (one battery-type electrode and the other capacitive-type electrode) that deliver high-power performance.
(3) Design of electrocatalytic bi-functional cathodes for metal-air batteries that have significantly capacity retentions and flexibility upon long cycles.

Keywords: Na-ion battery, Zn-ion battery, hybrid battery, pseudocapacitive effect, high power energy storage.

References:

Dongliang Chao, et al., Adv. Mater. DOI: 10.1002/adma.201804833.

Ming Song, et al. Funct. Mater. Invited Review, DOI: 10.1002/adfm.201802564.

Dongliang Chao, et al, Mater. (2018), DOI: 10.1002/adma.201803181.

Dongming Xu, et al., Energy Mater. DOI: doi.org/10.1002/aenm.201702769.

Huanwen Wang, et al, Non-Aqueous Hybrid Lithium and Sodium Ion Capacitors, Adv. Mater. 1702093 (2017)