bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gallium Arsenide As an Alloying Anode for Lithium Ion Batteries
Authors: Hays Kevin Alan , Banek Nathan A , Wagner Michael J 
Published: February 2020

Li alloying metals have much greater specific and volumetric energy densities than current state of the art graphite used in commercial Li ion batteries. However, the extremely large volumetric changes that the metals undergo when alloying with Li lead to the structural degradation of the electrode with consequent poor cycle life. We are attempting to make stable Li alloying metal electrodes, specifically with gallium arsenide, by akalide reduction on carbon matrices.
Arsenic has been largely ignored as a candidate for Li alloying anode materials despite having the third best gravimetric capacity of the alloying metals and being abundant and inexpensive, on par with the cost of bulk silicon1. Gallium, a lithium alloying metal that melts at 29.8°C, has shown promise because of its self-healing ability at increased temperatures2, although it suffers from a lower gravimetric capacity than some of its more popular lithium alloying counterparts.
Here we show the synthesis of Gallium Arsenide by akalide reduction. It is characterized by powder x-ray diffraction, transmission electron microscopy, thermo-gravimetric analysis, and x-ray fluorescence spectroscopy. Electrochemical testing of lithium half-cells, cycled from 0.02 to 1.5V versus lithium at a rate of C/10, showed a reversible capacity of 1365 mAh/g with good capacity retention.
(1) Nitta, N.; Yushin, G. Particle & Particle Systems Characterization, 31, 317-336.
(2) Deshpande, R. D.; Li, J. C.; Cheng, Y. T.; Verbrugge, M. W. Journal of the Electrochemical Society, 158, A845-A849.

Figure 1
Oxide-Based Synaptic Transistors for Neuromorphic Systems
Authors: Wan Qing 
Published: February 2020

Inspired by the energy-efficient and cognitive computational ability of a biological brain, neuromorphic computing is an attractive computation paradigm that complements the von Neumann architecture. Hardware implementations of synapses, dendrites and spiking neural networks represent a promising computational paradigm for solving complex pattern recognition and sensory processing tasks. Here, artificial electronic synapses and dendrites are proposed based on the oxide-based electrical-double-layer transistors. Strong electrostatic coupling effect and electrochemical doping were observed due to proton migration in the P-doped SiO2 electrolyte films. Protons in the P-doped SiO2 electrolyte and oxide channel conductance were regarded as the neurotransmitter and synaptic weight, respectively. Spike-timing dependent plasticity, short-term plasticity, including paired-pulse facilitation, dynamic filtering was mimicked. Most importantly, dendritic arithmetic and spiking pH sensors with extremely low energy dissipation of 0.5pJ are also demonstrated in a simple artificial synapse with multiple pre-synaptic inputs. Our oxide-based protonic/electronic hybrid artificial synaptic transistors are potential building blocks for brain-inspired computers and neuromorphic systems.
[1] L. Q. Zhu, C. J. Wan, L. Guo, Y. Shi, and Q. Wan*. Nature Communications, 5, 3158, 2014.
[2] C. J. Wan, L. Q. Zhu, J. M. Zhou, Y. Shi, Q. Wan*. Nanoscale. 6, 4491, 2014.
[3] C.J. Wan, L. Q. Zhu, Y. H. Liu, Y. Shi, and Q. Wan*. IEEE Electron Device Letters. 35, 672, 2014.
[4] L.Q. Guo, Q. Wan*, C. J. Wan, L. Q. Zhu, Y. Shi. IEEE Electron Device Letters. 34,1581, 2013.
[5] M.Z. Dai, Q. Wan*. Nano Letters 11, 3987, 2011.
(Invited) Monolithic Integration of III-V As- and P-Based Devices on Si through Direct MBE Growth and Using Lattice Engineered Substrates
Authors: Lubyshev Dmitri , Fastenau Joel , Liu Amy , Wu Ying 
Published: February 2020

Mainstream silicon (Si) CMOS technology is finally experiencing limitations of pure Si-based material and process. For digital electronics, to extend Moore’s law, the industry increasingly is investigating alternative materials and technologies to enhance channel transport properties and reduce power dissipation for future generation transistor circuitry. Heterogeneous integration of compound III-V semiconductor devices on Si may realize high performance integrated circuits for analog and digital applications and can incorporate optoelectronic components for high-speed data transfer. Such integration provides the combined advantages of high volume production of Si-based electronic circuitry with superior high-speed performance of III-V components. At IQE, we developed molecular beam epitaxy (MBE) growth processes for the production of high quality III-V based transistor structures monolithically integrated onto CMOS-compatible substrates by direct MBE growth on Si wafers and also by utilization of specialized Si-on-Lattice-Engineered-Substrate (SOLES) substrates.
Through work with industry partners, IQE has grown InP-based high electron mobility transistor (HEMT) and quantum well field effect transistor (QWFET) structures directly on Si substrates by MBE. Following a high-K gate dielectric fabrication process, QWFET devices demonstrated high transconductance of 1750μS/μm and high drive current of 0.49mA/μm at VDS=0.5V.
[1]
As part of a program funded by the US Defense Advanced Research Projects Agency, IQE developed a direct MBE growth approach of an InP-based heterojunction bipolar transistor (HBT) structure on the SOLES substrates, and together with our collaborators successfully created clusters of high-speed III-V HBT circuitry monolithically integrated side-by-side with Si CMOS on the same wafer.
[2]

In this paper, we will discuss structural and electronic properties of epitaxial device material, including dislocation filtering in the mismatched metamorphic buffers, and compare performance of devices fabricated on Si with reference material grown on lattice-matched InP substrates.

[1] Radosavljevic, M.; Chu-Kung, B.; Corcoran, S.; Dewey, G.; Hudait, M. K.; Fastenau, J. M.; Kavalieros, J.; Liu, W. K.; Lubyshev,D.; Metz, M.; Millard, K.; Mukherjee, N.; Rachmady, W.; Shah, U.; Chau, R. (2009), IEDM Tech. Dig., p.13.1.
[2] W. K. Liu, D. Lubyshev, J. M. Fastenau, Y. Wu, M. T. Bulsara, E. A. Fitzgerald, M. Urteaga, W. Ha, J. Bergman, B. Brar, W. E. Hoke, J. R. LaRoche, K. J. Herrick, T. E. Kazior, D. Clark, D. Smith, R. F. Thompson, C. Drazek, and N. Daval, J. Crystal Growth, 311, 1979 (2009).
(Invited) Plasma Etching Technology Challenges for Future CMOS Fabrication Based on Microwave ECR Plasma
Authors: Izawa Masaru , Tanaka Motohiro , Yasui Naoki , Morimoto Michikazu 
Published: February 2020

As dimensions of semiconductor devices shrink further into the nanometer range, transistor performance is improved not only by scaling and adopting boosting technology, but also by adopting new channel material and structure. It is also required to reduce power consumption for mobile devices. In MOS logic devices, 3D-trasistor (FinFET) was adopted to improve switching property. When fabricating, more accurate and higher aspect ratio patterning is required, e.g. fin width reaches 3.7 nm at the 5nm node, where nanowire FET and Ge/III-V channel materials are other candidates [1]. Thus, required accuracy will reach atomic level in the etching process. To realize nm scale etching, new etching process functions are necessary to suppress wiggling, roughening, and degradation of etched layer. At the same time, reasonable productivity is required for mass production.
To improve etched profiles, we have been investigated and improved microwave ECR plasma etch tool, e.g. installation of time modulation (pulsing of RF bias, discharge, and gas) technologies, accurate power control of wafer RF bias, end-point monitor, and so on. TM bias (wafer RF bias pulsing) technology is already used in semiconductor fabrication [2]. Lower RF bias power and zero bias condition were effective for extremely high-selective etching.
Microwave ECR plasma tool seems to have good affinity to pulsing discharge because it was designed to avoid the drift of plasma density. By using the pulsing discharge, wiggling was suppressed dramatically in DSA mask etching [3].
Gas pulsing technology was also investigated for fin etching. Etching progress and sidewall protection steps were changed cyclically without interruption of the discharge. It was found that etched profile (vertical, etch front flatness, and mask selectivity) was improved [4].
Atomic level precision etching is required in future MOS device fabrication where etched material, etch stop layer, and structure become more complicated. It will be necessary to control lower ion incident energy with vertical direction, lower the gas dissociation to reduce aggressive radical generation and reduce sidewall deposition. We believe multi-pulsing technology (discharge, bias, and gas) and low bias power control at low pressure operation are key technologies to realize atomic level precision etching.
[1] ITRS 2013.
[2] T.Ono el al, JJAP. 38, 5292 (1999).
[3] M. Morimoto et al., SPIE 2014 [9054-18].
[4] M. Tanaka et al., JSAP Autumn meeting, 19p-S10-7, 2014.
Ag-Fe2O3 Heterostructured Nanoparticles as Photocatalysts under Visible Light Irradiation
Authors: Liu Shiben , Chen Yingjie , Dong Lifeng 
Published: February 2020

Due to the synergistic effect between different composites, an increasing number of functional semiconductor-metal hybrid nanomaterials with core-shell or heterostructure geometry has been fabricated and proposed as the preferred form of catalysts. For example, Au@Co3O4 core-shell nanostructures showed higher oxygen evolution reaction activity than a mixture of Au and Co3O4 nanoparticles, or Co3O4 and Au nanoparticles alone. In addition, PbS-Ag heterostructure nanotubes exhibited significantly enhanced photocatalytic activity.
Thanks to the controlled syntheses of semiconductor-metal nanocomposites with desired morphologies, it has been feasible to study the nanostructure tuning capacities. Herein, Ag-Fe2O3 core-shell and heteromer nanocomposites were synthesized by a seed-mediated growth method reported previously, and hollow Fe2O3 nanoparticles were obtained by the transformation of Ag-Fe2O3 core-shell nanocomposites. Subsequently, the photocatalytic activity of Ag-Fe2O3 core-shell nanocomposites was directly compared with that of Ag-Fe2O3 heteromer and hollow Fe2O3 nanoparticles, respectively. Finally, we could demonstrate experimentally whether the enhanced photocatalytic activity of Ag-Fe2O3 core-shell arise from its wide absorbance range of visible light and favorable charge separation. This investigation would help us to further understand nanostructure tuning capacity of nanocomposites and control their syntheses for a given application.
Invited: Point Defects in Chalcogenide Compound Semiconductors
Authors: Rockett Angus 
Published: February 2020

The II-VI chalcogenide semiconductors are used widely in applications ranging from phase change memory materials to photovoltaics. In some cases, such as phase change materials, defects are relatively unimportant while in optoelectronic devices such as photovoltaics, these defects are critical. Indeed, this ultimately led to the choice of III-V nitrides over the II-VI compounds for visible light emitters. This talk focuses on materials primarily used for photovoltaics and photosensors, as this has been the most successful application of the chalcogenides in optoelectronic devices. When one considers the series of increasingly ionic semiconductors Ge, GaAs, ZnSe, and CuBr, the impact of grain boundaries on device performance continuously decreases, allowing practical devices made from chalcogenide polycrystals. Remarkably, many devices work better as polycrystals than as single crystals. This is because valence compensation is increasingly important and point defects are easily created that passivate extended defects. At the same time, when one considers the sequence ZnSe, CuInSe2, Cu2ZnSnSe4, the increasing complexity of the compounds leads to an ever increasing potential for formation of detrimental point defects and second phases. Ordering of point defects is common in these materials and can mitigate their effects and lower their formation energy, allowing significant deviation from stoichiometry without loss of performance. These topics and the experimental evidence related to their activity are reviewed in this talk, primarily focusing on the chalcopyrite materials as examples and photovoltaics as the application. Selected advanced characterization methods such as scanning microwave microscopy for study of the materials are also noted.
(Invited) GaN High Power Devices and Their Applications
Authors: Mun Jae-Kyoung , Chang Woojin , Kang Dong Min 
Published: February 2020

Wideband gap semiconductors, such as GaN and SiC, are called as next generation compound semiconductor platform. In material aspect, GaN has wideband gap energy(Eg=3.4eV), excellent electron transport properties, including good mobility, and high saturated drift velocity. So, GaN-based HEMT devices are attractive candidates for high-power amplifiers for communication and radar systems, and high power electronic switching devices for high efficient energy conversion systems.[1-5]

We started the R&D of GaN technologies in 2010, and the progress of GaN RF device and power amplifier technologies will be presented today. Especially, I’d like to mention about recent demonstration of GaN power HEMTs developed using the ETRI’s proprietary 4-inch GaN full process for S-band and X-band ship radar systems. We are developing high power GaN devices technologies using two platforms. One is a GaN-on-Si for cost-effective power electronic device solutions and the other a GaN-on-SiC for performance-oriented power amplifier device solutions. But my presentation will be focused on the high power amplifier devices technologies and recent radar demonstration results.
A 200W solid state power amplifier (SSPA) was developed using ETRI’s 100W GaN transistors and mounted it on the S-band ship radar system. We tested and successfully got good radar images. To evaluate our device performance, we made and installed two kinds of high power SSPA modules using ETRI’s and Cree’s commercial GaN HEMTs products, respectively. Using these modules, we performed comparative study on the radar images each other. This is the first demonstration of SSPA ship radar in Korea. Test results were almost same and will be presented in this conference.

References:

1. Millan, J. “Wide band-gap power semiconductor devices”, IET Circuits Devices Syst., Vol.1(5), pp. 372–379(2007).
2. Jae Kyoung Mun, RF Integrated Circuit Technology Workshop 2011, pp. 483-495.
3. Jae Kyoung Mun et. al.,“Current Status of GaN Technologies in ETRI”, AWAD 2012.
4. Jae Kyoung Mun, “Current Status of S-/X-/Ku- Band GaN Transistors in ETRI”, 6th Microwave and Millimeter-Wave Components Workshop for Military Applications(2012)
5. Jae Kyoung Mun et. al.,“Current Status of GaN Power Electronic Device Technologies in ETRI”, ICAE 2013.
6. Youngrak Park et al, ELECTRONICS LETTERS, Vol. 50 No. 16, pp. 1164–1165(2014)
Impact of Microstructure and Defects on Surface Reactivity during Wide Bandgap Semiconductor Epitaxy
Authors: Yanguas-Gil Angel , Zapol Peter 
Published: February 2020

A great amount of research on wide bandgap semiconductors is currently focused on point and 1D defects, due to its key role in device performance. It is therefore surprising that the interplay between defects and surface kinetics is relatively unexplored. There is a strong interaction between these two aspects that goes both ways: surface kinetics can promote the formation of surface defects that get subsequently incorporated into the bulk. If we were able to predict the role that surface kinetics has on defect formation, this would allow us to greatly assist process development to achieve a further reduction in the density of defects. Conversely, surface defects and surface morphology affects the reactivity of the surface, and this can lead to intra-wafer variability based on the morphology and defect density at different points of a wafer substate. However, despite this strong correlation, the atomistic aspects of precursor-surface interaction are not well understood.
In this talk we will focus on the impact of surface morphology and defects on the surface reactivity during epitaxy. In a step flow growth mode, the density of step sites will play an important role in the overall reaction probability of the different surface species. We have therefore developed models that explore the interaction between the effective reactor probability (the probability that a precursor molecule reacts with the surface) and both surface morphology and defect concentration. One of our key results is that, under the reaction-limited conditions in which the growth rate is linear with precursor concentration, it is possible to greatly accelerate the determination of the statistical outcome of precursor-surface interaction. We can use this information to understand where particles are more likely to react locally on the surface and the relative stability of certain surface configuration. We have used this result to investigate the impact that surface residence time has on the reaction probability as a function of miscut and in the presence of thread screw dislocations, and the role that step roughening can have in promoting surface vacancies that can lead to point defects in the solid.
Hydrothermally Grown Nonpolar a-Plane ZnO and Its Applications
Authors: Kim Jimin , Baik Kwang Hyeon , Jang Soohwan 
Published: February 2020

There has been great interest in ZnO as promising alternative light emitting material. It has wide direct bandgap of 3.37 eV and large exciton binding energy of 60 meV. A diverse of growth methods have been developed for ZnO epitaxial layer growth such as laser-assisted plasma enhanced chemical vapor deposition (PECVD), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and hydrothermal synthesis. Among them, hydrothermal growth is the cost-effective, environmentally friendly, and low thermal budget requiring process compared to conventional MOCVD. Most of hydrothermally grown ZnOs are in the shapes of nanorod or nanowire along c-axis due to fast growth rate of c-plane.
Commercially available LEDs are based on GaN related material system, which is grown along the polar c-axis of wurtzite crystal structure. In this crystal, there exists spontaneous and piezoelectric polarization inducing internal electric fields which result in spatial separation of electron and hole wave functions. This quantum confined stark effect (QCSE) causes reduction in radiative recombination efficiency under high current injection. As one of solution, extensive efforts on nonpolar a-plane GaN are exerted.
Nonpolar a-plane ZnO with high crystalline quality was successfully grown on a-plane GaN tempelate by simple, low-cost, and mass producible hydrothermal method. Synthesized a-plane ZnO thin film was studied with SEM, TEM, XRD, AFM, and PL analyses. In this presentation, growth of hydrothermal ZnO and its applications will be introduced.
(Invited) Investigations and Improvements of AlInN/GaN HEMTs Grown on Si
Authors: Chyi Jen-Inn , Hsin Yue-Ming , Lee Geng-Yen , Chiu Hsien-Chin 
Published: February 2020

GaN-based high electron mobility transistors (HEMTs) have attracted tremendous attention because of its wide bandgap and high power handling capability, which are the two fundamental merits for power electronics applications. Lattice-matched AlInN/GaN heterostructure has been considered a promising alternative to its AlGaN/GaN counterpart due to its stronger spontaneous polarization, which induces higher carrier concentration and therefore reduces channel resistance. In addition, InAlN lattice-matched to GaN would not be subject to the inverse piezoelectric effect that deteriorates device reliability as observed on AlGaN/GaN HEMTs. While a few excellent device characteristics have been demonstrated over the years, AlInN/GaN HEMTs are in general still more vulnerable than AlGaN/GaN HEMTs. It is desirable to clarify the origin(s) of this problem to expedite the development of high power AlInN/GaN HEMTs and the devices alike. In this talk, we will present our recent works on the growth and electrical characterization of AlInN/GaN HEMTs, including capping layer designs, off-state breakdown mechanisms, dynamic resistance measurements as well as low frequency noise measurements. Solutions to cope with the material issues and process issues will also be addressed.
Effects of Chemical Doping and Defect Density on Electrical and Optical Properties of Graphene As a Transparent and Conductive Electrode
Authors: Oh Sooyeoun , Yang Gwangseok , Jung Younghun , Kim JiHyun 
Published: February 2020

Indium tin oxide (ITO) has been commonly used as a transparent and conductive electrode in many applications owing to its outstanding electrical conductivity and transparency. However, ITO still suffers from limited resource, low transmittance at UV and IR region, chemical instability, poor flexibility and complex fabrication process. Recently, graphene is considered as one of the ideal materials for transparent and conductive electrodes because it has intriguing properties such as high conductivity, transmittance at wide wavelength ranges, flexibility and so on. But its high sheet resistance compared to that of ITO needs to be improved. Chemical doping of graphene can be used to reduce its sheet resistance. Similarly, defects in graphene can affect its electrical, optical properties and chemical sensitivity. Therefore, we investigated the effects of chemical doping and defects on graphene.
In our experiments, single layered graphenes grown by chemical vapor deposition method on Cu-foil were used. The details of the results will be presented at the meeting.
Analysis of Patterned Defects on Graphene Using Micro-Raman Spectroscopy and Liquid Crystals
Authors: Yang Gwangseok , Oh Sooyeoun , Kim JiHyun 
Published: February 2020

Graphene has been used in various applications such as light-emitting diodes, solar cells, transistors, and chemical sensors because of its intriguing properties. Since defects in graphene can affect its intrinsic properties, defect characterizations in graphene are crucial. Micro-Raman spectroscopy has been considered one of the powerful and non-destructive techniques to analyze fundamental properties of graphene. Since fast characterization of large-area graphene is critical for its commercialization, large-area graphene was analyzed using liquid crystal with polarized optical microscopy at different temperatures.
Chemical-vapor-deposited graphene was transferred onto pre-patterned SiO2/Si substrate by using conventional wet-transfer method. Defects were intentionally generated by oxygen plasma for various treatment times. The details of our experiments and results will be discussed in the meeting.