bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma-Enhanced Atomic Layer Deposition of Iron and Titanium Phosphates as Electrode Materials for 3D-Structured Lithium-Ion Microbatteries
Authors: Dobbelaere Thomas , Mattelaer Felix , Dendooven Jolien , Vereecken Philippe M. , Detavernier Christophe 
Published: February 2020

Iron phosphates are widely used as polyanion-based positive electrode materials for lithium-ion batteries. In light of the considerable academic and industrial interest in the development of solid-state 3D-structured thin-film lithium-ion batteries, where the conformal deposition of very thin and pinhole-free electrode films on complex structures is an essential requirement, we have developed a plasma-enhanced ALD process to deposit amorphous iron phosphate at an unusually high growth rate of 1.1 nm/cycle.
Our deposition process is based on alternating exposures to trimethyl phosphate (TMP, Me3PO4) plasma, O2 plasma, and tert-Butylferrocene (TBF) vapor. The main novelty of the process lies in the use of a TMP plasma as the phosphorus source, according to a mechanism which we recently reported for the deposition of aluminum phosphate (Dobbelaere et al., Chem. Mater. 2014, 26, 6863−6871).
Firstly, we performed a detailed characterization of the deposition process of iron phosphate, including in-situ growth monitoring by spectroscopic ellipsometry and an investigation of temperature and pulse time dependency. Linear growth was observed without nucleation delay, proceeding optimally at 300°C. Saturation behavior could be demonstrated for all exposure steps, confirming a PE-ALD process.
Secondly, we studied the properties of the deposited films. The as-deposited amorphous films had a density of 3.1 g/cm3 and ERD analysis revealed an empirical stoichiometry of FeP1.5O4.7 with 0.9% hydrogen and no detectable carbon residue (fig. 1a). Post-deposition annealing in air resulted in the formation of trigonal FePO4, while the same anneal in helium resulted in the formation of elemental phosphorus.
Finally, we investigated the electrochemical behavior of the as-deposited iron phosphate in lithium-ion test cells. Cyclic voltammetry measurements showed lithiation and delithiation around 3V vs. Li/Li+, albeit reaching only 8% of the theoretical capacity. However, by reduction below 0.5V and subsequent oxidation back to 3V, we observed a drastic capacity increase to 60% of the theoretical capacity, resulting in an active 3V cathode material. Long-term charge/discharge cycling of a 33 nm planar film revealed that the capacity decreases over the first 10 cycles, and then stabilizes to 0.7 μAh/cm2. On a 3D micropillar substrate, the capacity increased from 7 μAh/cm2 to 22 μAh/cm2 over the first 150 cycles, and then remained constant at 22 μAh/cm2. Rate testing (fig. 1b) showed that both electrodes can be used at high C-rates, proving that the capacity is greatly enhanced by 3D structuring without sacrificing kinetics.

Figure 1: (a) depth profile of a 55 nm iron phosphate film on a silicon substrate; (b) comparison of charge/discharge capacity and rate capability between planar and 3D-structured electrodes.

Figure 1
Effects of SiO2 and TiO2 Combination Coating on TiO2 Nanoparticle Electrodes in Dye Sensitized Solar Cells
Authors: Kanomata Kensaku , Kato Yuki , Imai Takahiro , Miura Masanori , Ahmmad Bashir , Kubota Shigeru , Hirose Fumihiko 
Published: February 2020

Dye sensitized solar cells (DSCs) have attracted much attention since the DSCs have cost advantages compared with the conventional Si solar cells. To achieve the high power conversion efficiency in the DSC, it is necessary to enhance the dye adsorption on the TiO2 nanoparticles. To achieve the high-density adsorption, we examined the TiO2 coating on the TiO2 nanoparticles since it might play a role for over-coating on naturally contaminated impurities on the nanoparticle surface. In addition, to obtain high power conversion efficiency in the DSCs, it is necessary to prevent carrier recombination between the electrolyte and TiO2 nanoparticle electrode. It is assumed that the recombination can be prevented by an energetic barrier of SiO2 between TiO2 / electrolyte. To deposit TiO2 on the nanoparticle, we used a plasma enhanced atomic layer deposition (ALD). The precursor was tetrakis(dimethylamino) titanium (TDMAT). The oxidizing agent was plasma-excited humidified argon. The growth per cycle of TiO2 is estimated as 0.15 nm/cycle. To deposit SiO2 on the TiO2 coated nanoparticles, we used the same ALD system. The precursor was tris(dimethylamino)silane (TDMAS). The oxidizing agent was the same oxidizer as that in case of TiO2. The growth per cycle of SiO2 is estimated as 0.066 nm/cycle. In this experiment, we used N719 as the sensitizing dye. We show J-V characteristics of the DSCs with the SiO2 and TiO2 combination coating in figure 1. The short circuit current density is improved from 10.04 mA/cm2 to 13.16 mA/cm2 while the open circuit voltage remains unchanged around 0.74 V. With the 10 cycle ALD of TiO2 and one cycle ALD of SiO2, the power conversion efficiency is improved from 5.41 % to 7.03 %. We consider that the combination coating prevents the carrier recombination between the electrolyte and ALD-TiO2 coated nanoparticle electrode.
Acknowledgement; This work was partly supported by JST-CREST, JSPS KAKENHI Grant Numbers 15H03536 and 15K13299.

Figure 1
Synthesis of Cerium-Oxide Coated Platinum Core-Shell Structure Catalysts with Enhanced Stability and Activity via Atomic Layer Deposition
Authors: Cao Kun , Shi Lu , Cai Jiaming , Shan Bin , Chen Rong 
Published: February 2020

Platinum nanoparticles (NPs) play an important role in the catalytic applications such as conversion of automotive exhaust, fuel cells, nano sensing and so on. For many of catalytic applications, agglomeration of Pt NPs is undesired because the coalescence results in a decrease of surface active sites.1 Many approaches have been explored to prevent agglomeration, the formation of core shell structures to encapsulate the noble metal nanoparticles seems to be a viable way.2,3

Herein we report the utilization of active oxide layers to encapsulate Pt NPs through atomic layer deposition. Besides the outstanding sintering resistance by physical anchoring, the active oxide decorated composite catalysts have additional metal-oxide interfaces that may further enhance the catalytic activity. HRTEM characterizations and DFT simulations have shown that oxide layers initially preferred to deposit on Pt (111) to form an incontinuous coating layer. The Pt-oxides model catalysts were prepared on planar Al2O3 supports to obtain a molecular level understanding of the catalytic process. It is found that Pt nanoparticles with all kinds of oxide coating layers have demonstrated not only the good sintering resistance under atmosphere condition, but also the lower CO oxidation conversion temperature than bare Pt nanoparticles.
References:

K. Hayashi, T. Horiuchi, K. Suzuki, Catalysis Letters, 78, 2002

K. Cao, B. Huang, Y.H. Zhang et al. ECS Transactions, 64(9), 159-166, 2014

J. Lu, B. Liu, J. P. Greeley, Chemistry of Materials, 24, 2047-2055, 2012
High Performance Asymmetric V2O5-SnO2 Nanopore Battery By ALD
Authors: Liu Chanyuan , Lee Sang Bok , Rubloff Gary W 
Published: February 2020

An array of nanobatteries, each self-aligned and fully confined within a single nanopore, provides an effective testbed for the rate performance and cyclability limits of nanostructured storage devices. With atomic layer deposition (ALD), we have previously synthesized and evaluated such structures in a symmetric configuration, comprised of nanotubular V2O5 electrodes as both anode and cathode and electrolyte confined within anodic aluminum oxide (AAO) nanopores. Each nanopore battery has ultra-small volume (~1fL) and shows superior performance when tested as massively parallel device (~2billion/cm2).
[i]
However, an asymmetric full cell configuration with a low voltage anode material has not been explored yet.
Here we report an asymmetric full cell nanopore battery, comprised of V2O5 as cathode and prelithiated SnO2 as anode, with integrated nanotubular Pt current collectors underneath each nanotubular storage electrode. Also enabled by ALD, this coaxial nanotube full cell is fully confined within the high aspect ratio nanopore (150nm in diameter, 50um in length). By controlling the amount of lithium ion prelithiated into SnO2 anode, we can tune full cell output voltage in the range of 0.3V and 3V. This asymmetric nanopore battery array displays exceptional rate performance and cyclability. When cycled between 1V and 3V, it has capacity retention of approximately 73% at 200C rate compared to 1C, with only 2% capacity loss after more than 500 charge/discharge cycles. With increased full cell output potential, the asymmetric V2O5-SnO2 nanopore battery shows significantly improved energy and power density. This configuration presents a more realistic test - through its asymmetric (vs symmetric) configuration – of performance and cyclability in nanoconfined environment.

[i] Liu, C.; Gillette, E. I.; Chen, X.; Pearse, A. J.; Kozen, A. C.; Schroeder, M. A.; Gregorczyk, K. E.; Lee, S. B.; Rubloff, G. W., An all-in-one nanopore battery array. Nature Nanotechnology
2014,
9 (12), 1031-1039.
Synthesis and Electrode Performance of Li3NbO4 - LiVO2 Binary System for Li Batteries
Authors: Yabuuchi Naoaki , Nakajima Mizuki 
Published: February 2020

Rechargeable lithium batteries are used for electric vehicles, and the demand for high-energy and long-cycle-life positive electrodes is growing. Recently, Li1.3Nb0.3V0.4O2 with a cation-disordered rocksalt structure has been reported as a positive electrode material, which delivers high reversible capacity of >200 mAh g-1 with V3+/V5+ two-electron redox.[1] However, for Li1.3Nb0.3V0.4O2, 0.5 mole of Li+ remains in the crystal lattice after fully charge, and therefore further increase in the energy density is anticipated through the optimization of chemical compositions. In this study, we systematically examine crystal structure and electrochemical properties of x Li3NbO4 – (1 – x) LiVO2 binary system as positive electrode materials for rechargeable lithium batteries.
Li-Nb-V-O samples were prepared by a solid-state reaction from stoichiometric amounts of Li2CO3, V2O3 and Nb2O5. The mixtures of precursors were calcined at 950 oC for 12 h in inert atmosphere. Thus prepared samples were mixed with acetylene black by mechanical ball-milling. The samples were characterized by XRD and SEM. Electrochemical properties as positive electrode materials were examined using two-electrode electrochemical cells.
X-ray diffraction patterns of the binary system of x Li3NbO4 – (1 – x) LiVO2 with different compositions are shown in Figure 1 (a). Li1.3Nb0.3V0.4O2 (x = 0.43) crystallizes into cation-disordered rocksalt phase whereas partially cation-ordered rocksalt phase is found for Li1.25Nb0.25V0.5O2 (x = 0.33) and Li1.2Nb0.2V0.6O2 (x = 0.25). Electrochemical properties of the samples are also shown in Figure 1 (b). The cells were galvanostatically cycled at a rate of 10 mA g-1 in the voltage range of 1.5 – 4.8 V at room temperature. Among three samples (x = 0.25, 0.33, and 0.43), the highest reversible capacity of >250 mAh g-1 is obtained for Li1.25Nb0.25V0.5O2 (x = 0.33). Moreover, electrode performance is further increased by heat treatment of the samples.
From these results, we will discuss the possibility of x Li3NbO4 – (1 – x) LiVO2 binary system with V3+/V5+ two-electron redox as high-capacity and long-cycle-life positive electrode materials for rechargeable lithium batteries.
(1) N. Yabuuchi et al., Chem. Commun.,
52, 2051 (2016).

Figure 1
In-Situ Boron Doped SiGe Epitaxy Optimization for FinFET Source/Drain
Authors: Qi Yi , Peng Jianwei , Lo Hsien-Ching , Holt Judson Robert , Willemann Michael , Gaire Churamani , Evans Sarah , Flanagan Patrick , Yu Hong , Hu Owen , Kennett Michael 
Published: February 2020

In-situ Boron doped embedded SiGe epitaxy has been widely used for CMOS source/drain in advanced technology nodes, from its introduction in planar devices to its more recent application in FinFETs. Compared to planar technology, FinFETs have the benefit of improved short channel effect, which allows for significantly higher in-situ doping level for lower contact resistance.
This work explores the source/drain expitaxy design differences between planar and FinFET transistors, and how the in-situ doped epitaxy process can be optimized to address the call for a higher doping level in the FinFET source/drain. In particular, we observe a competing relationship between Germanium and Boron incorporation -- increasing Ge incorporation generally lowers boron doping, and increased boron incorporation generally lowers Ge. However, our work shows that the limit of Boron doping can be boosted by increasing Ge percentage, and furthermore we propose a Si-Ge-B phase diagram based on this experimental data. Outside of the soluble area of the phase diagram defective epitaxy is observed, featuring Boron-rich incoherent phase or Boron segregation. Finally, we present device data that show the performance benefit when Ge% and Boron is optimized according to the phase diagram, characterized by lower Ron and higher drive current.
Annihilation of Threading Dislocations in Strain-Relaxed Si1-XGex Layer By Hydrogen Ion Implantation
Authors: Park Jun-Seong , Kim Il-Hwan , Shin Hyeon-Ju , Shim Tae-Hun , Lee Gon-Sub , Park Jea-Gun 
Published: February 2020

According to the international technology roadmap for semiconductor (ITRS), the development of MOSFETs based on the strain technology is necessary for the next generation technology beyond 10-nm C-MOSFETs. By being applied the strain in the channel of MOSFET, the electron mobility can be enhanced results in the higher current in MOS channel at the fixed gate voltage and oxide thickness. However, due to the lattice mismatch of 4.2 % between Si and Ge, many threading dislocations are generated during the epitaxial growth, resulted in increasing the leakage current of the C-MOSFETs. Currently, the threading dislocation density of 3-µm-thick X-at% (>30-at%) graded Si1-xGex layer is higher than 105 cm-2, which is too high level to be applied in mass production because of degrading the productivity and the performance of the C-MOSFETs.
In this study, for that reason, to reduce threading dislocations in the strain-relaxed Si1-xGex layer, we investigated how the hydrogen ion implantation annihilated the threading dislocations in strain-relaxed Si1-xGex layer/Si (100) substrate. First, a relaxed Si1-xGex layer was grown on a Si (100) substrate by epitaxial growth. Second, hydrogen ions were implanted onto the interface between the strain-relaxed Si1-xGex layer and the Si substrate. After ion implantation, the sample was annealed at 800oC for 30 min in a nitrogen ambient. For the case of hydrogen ion implantation with a dose of 5ⅹ1015 cm-2, it was confirmed that the cross-hatch pattern density and the surface roughness was decreased and threading dislocations near the interface were not observed in hydrogen ion-implanted Si1-xGex/Si wafer as shown in Fig. 1. In addition, as shown in Fig. 2, by using in-situ real-time high-resolution TEM, it was confirmed that a threading dislocation in hydrogen ion-implanted Si0.7Ge0.3 layer/Si substrate was annihilated with hydrogen-related defect while the TEM specimen was being annealed at 600oC for 30 min in the heating holder.
Therefore, we present the formation mechanism of threading dislocations in a strain-relaxed Si1-xGex layer/Si (100) substrate and the annihilation mechanism of how the threading dislocations are annihilated by hydrogen ion implantation.
* This work was financially supported by the Brain Korea 21 Plus Program in 2016 and SiWEDS (Silicon Wafer Engineering and Defect Science).

Reference

[1] J. G. Park et al., Mat. Sci. Eng. B
134 142-153 (2006)

[2] S. Takagi, Strained-Si CMOS Technology in Advanced Gate Stacks for High-Mobility Semiconductors, Springer Berlin Heidelberg 1 (2007)

Figure 1
Optical Isolator with Si Guiding Layer Fabricated by Photosensitive Adhesive Bonding
Authors: Yokoi Hideki , Choowitsakunlert Salinee , Kobayashi Kouya , Takagiwa Kenji 
Published: February 2020

INTRODUCTION
In optical communication systems, an optical isolator is indispensable in protecting active photonic devices from unwanted reflected light. An optical isolator with a Si guiding layer is a significant device for silicon photonic integrated circuits. In this paper, the authors report on an optical isolator with the Si guiding layer fabricated by photosensitive adhesive bonding.
DEVICE STRUCTURE
Figure 1 shows an optical isolator with a Si guiding layer employing a nonreciprocal guided-radiation mode conversion [1]. A magnetic garnet cladding layer is bonded with the Si guiding layer by photosensitive adhesives. A cerium-substituted yttrium iron garnet (Ce:YIG) is used as the magnetic-garnet cladding layer [2]. The optical isolator is comprised of a straight rib waveguide with a Ce:YIG/Si/SiO2 structure. An external magnetic field is applied to the magneto-optic waveguide in film plane. TM modes travelling in the magneto-optic waveguide have distinct propagation constants for the forward- and the backward-travelling waves owing to a nonreciprocal phase shift. By adjusting waveguide parameters, the following relationship is satisfied:
β

b

y
< β

c

x
< β

f

y
(1)
where β

f

y
and β

b

y
denote the propagation constants of the forward- and the backward-traveling TM modes and β

c

x
denotes the cutoff of TE modes. Only the backward-traveling TM modes can couple to the TE radiation modes so that the device acts as a TM-mode optical isolator.
The optical isolator employing the nonreciprocal guided-radiation mode conversion was designed at 1.55 μm. The nonreciprocal phase shifts in the magneto-optic waveguides with various gap widths were calculated. It was confirmed that the nonreciprocal phase shift was reduced with increasing the gap width. The relationship of the waveguide parameters that satisfies equation (1) was investigated. Once the rib height was set, the range of the rib width for the isolator operation, which means that the propagation constants satisfy the relationship denoted by expression (1), was given. It was found that smaller gap width was desired for large tolerance of the waveguide parameters.
ACKNOWLEDGMENT
This work was partially supported by the SIT Research Center for Green Innovation.
REFERENCES
1. H. Yokoi, K. Sasaki and T. Aiba, Jpn. J. Appl. Phys., 48, 062202 (2009).
2. T. Shintaku, T. Uno and M. Kobayashi, J. Appl .Phys., 74, 4877 (1993).

Figure 1
Transfer of Ultra-Thin Semi-Conductor Films onto Flexible Substrates
Authors: Montméat Pierre , De Nigris Brandolisi Isadora , Tardif Samuel , Enot Thierry , Enyedi Gregory , Kachtouli Riadh , Besson Pascal , Rieutord François , Fournel Frank 
Published: February 2020

Applying tensile strain on an undirect band gap semiconductor crystal is a very promising way to tune it into a direct band gap
[1]
,
[2]
. This basic feature can be an outstanding progress for the use of classical semiconductor as silicon or germanium in interesting optoelectronic applications
[3]
. One way to apply a tensile strain is to transfer an ultra-thin of semiconductor onto a flexible substrate
[4]
(erg: an organic polymer). The goal of this paper is to propose a simple way to obtain an ultra-thin silicon film (<200 nm) onto an expendable polymer. It consists in transferring an Unibond™ SOI silicon thin film onto a classical tape maintain by a dicing frame. This process is mainly based on classical temporary bonding process.
As shown on figure, a first process is carried out onto 200 mm wafer with a SOI silicon film of 200nm and a buried oxide box of 400nm. No default is observed on the full stack after the grinding and etching steps used to remove the SOI backside substrate. No SiO2trace is also observed after the last dioxide etching. The thin silicon film is then characterized and no crack is observed. The stack is then laminated onto a frame with a Furukawa SP-537T-230 adhesive tape. The demounting of the carrier is easy and no default appears on the silicon film. The last process consists in removing the glue from the silicon. We obtain a 200 nm silicon film bonded onto the tape. Nevertheless, this glue removal leads to the appearance of some cracks ono the silicon thin film. A second process will then be presented in order to avoid the last glue removal steps and improving the final thin film quality. XRR characterizations of the transfered thin film will be presented as well as potential amount of tensile stress achievable with this unique structure.

[1] Ju Li et al., MRS Bulletin, 39, pp 108-114, 2014
[2] Feng Zhang et al., Phys. Rev. Lett. 102, 2009
[3] Diode Lasers and Photonic Integrated Circuits, Second Edition, 2012 John Wiley & Sons, chap 4
[4]& Salvatore Giovanni A.et al., ACS NANO Volume 7, Issue: 10, P8809-8815, 2013

Figure 1
Bond Strength of 3D-stacked Monocrystalline Silicon X-ray Mirrors
Authors: Girou David , Landgraf Boris , Gunther Ramses , Collon Max 
Published: February 2020

In view of high-performance light-weight X-ray optics, we developed a unique technology and assembly tool to stack structured and bend monocrystalline silicon plates resulting in a matrix-like pore structure, the so-called Silicon Pore Optics (SPO). The fully automated assembly robot is specifically developed to stack SPO of various sizes and is a combination of standard semiconductor systems and newly developed tools. The complete system has a footprint of a few square meters only and is installed in a particle free environment. The robot selects a plate for stacking and inspects it for particles. The plate is then handed over to the actual stacking tool, which will elastically bend it into a cylindrical or conical shape. After two bend and structured silicon plates have been hydrophilically bonded to each other, the figure and interfacial particular contamination is investigated with a Fringe Reflection Technique (FRT) machine. The process of stacking is getting repeated by the assembly tool till the stack reaches a height of up to 45 plates forming a stiff self supporting structure.
In this presentation, we will give account of the production of SPO with different radii. We will mainly focus on our investigations of the bond strength of the directly bonded structured silicon mirror plates. The investigation of the mechanical strength of bonds of structured plates is of high importance as the bond strength is difficult to estimate in FE modeling, but is a critical point in the overall mechanical stability of the SPO. We performed tensile testing measurements to quantify the bond strength of two different types of samples, flat and curved direct bonded structuredmonocrystalline silicon plates. The failure modes found during this tests are either separation of the bond or failure of the structured silicon plates. Thereby, the tensile test results show clearly what failure mode it is. Furthermore, we post-annealed the samples at various temperatures and for different times in order to increase the bond strength and thus improve the stability of the stacks.