bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studying Rare Earth Surface Treatment for Magnesium Using Scanning Electrochemical Microscopy
Authors: Wallace Gordon G , Jamali Sina S , Moulton Simon E , Weber Jan , Forsyth Maria 
Published: February 2020

Rapid dissolution of magnesium alloys in biological solutions limits its successful application as a biodegradable implant where a controlled dissolution/corrosion of magnesium along with healing of tissue is required. Treatment of magnesium surface with rare earth conversion layers has been subject of several studies 1–4 revealing its potential as a passivating layer. Given the biocompatibility properties of such surface treatments, two type of rare earth conversion layers based on Ce(NO3)3 and Pr(NO3)3 have been studied in this present work as surface treatment for AZ80X in simulated biological (buffered) solution. Conversion layers were formed by acid etching the Mg samples in 15mM HCl followed by immersion in 0.05 M Pr(NO3)3 or Ce(NO3)3solutions. Morphology and elemental composition of the conversion layers were characterized by SEM-EDXS.
Scanning electrochemical microscope (SECM) was used to investigate protective properties and degradation behaviour of Ce and Pr conversion layers on a local scale. Surface generation/tip collection (SG/TC) mode was used to study the hydrogen evolution rate and localization while AC mode was used to resolve the resistive/capacitive behaviour of conversion layer. Figure 1 represents the schematic SG/TC mode for probing the local hydrogen evolution. Self-healing properties of the conversion layer in presence of Ce3+ and Pr3+was also studied using SECM. Electrochemical impedance spectroscopy (EIS) was used to look at the changes in charge transfer and diffusion phenomena due to the formation of conversion layer and its degradation in the long term. Preliminary results have shown that Ce and Pr conversion layers improve corrosion resistance in the short term by producing an electrochemically stable surface. In the long term, however, conversion layer shows instability in simulated biological fluid and tends to degrade locally exposing the magnesium substrate to corrosive media.
1. A. Rudd, C. Breslin, and F. Mansfeld, Corrosion Science, 42, 275-288 (2000).
2. M. F. Montemor, a. M. Simões, and M. J. Carmezim, Applied Surface Science, 253, 6922-6931 (2007).
3. K. Brunelli, M. Dabalà, I. Calliari, and M. Magrini, Corrosion Science, 47, 989-1000 (2005).
4. M. Dabalà, K. Brunelli, E. Napolitani, and M. Magrini, Surface and Coatings Technology, 172, 227-232 (2003).
Figure 1 Schematic representation of SG/TC mode SECM for probing hydrogen evolution
Electrochemically Modulated Extraction of Neodymium
Authors: Kalu Egwu Eric , Anderson Shannon , Nilsson Mikael 
Published: February 2020

The separation of lanthanides and actinides using the liquid-liquid extraction technique poses a major challenge due to the chemical similarities of the two groups of metals. Hence, interest exists in devising a technique to improve the separation factor. The use of an imposed external field (electrochemical) to improve the liquid-liquid extraction has been explored in the literature with limited success due to conductivity issues. In this work, the use of reverse micelle solutions containing water/AOT-HDEHP/n-dodecane for improved electrical conductivity will be explored. The results of a feasibility study of electrochemical modulation of neodymium extraction using the reverse micelles/microemulsions will be presented.
Electrochemical impedance technique was used to determine the effect of molar content of water, Wo, on the reverse micelle solution conductivity. The distribution ratio of Nd in an electrochemically modulated liquid-liquid extraction containing reverse micelles will also be presented. The mechanism of electrochemical modulated liquid-liquid metal ion extraction will be explored.
Characterization of Nanocomposite Based on Carbon Nanotubes and Conducting Polymers with Different Dopants for Obtaining of Modified Electrodes
Authors: Branzoi Florina , Branzoi Viorel , Pahom Zoia 
Published: February 2020

Nanocomposite films of functionalized single-walled carbon nanotubes (SWCNTs), 3,4-ethylene dioxythiophene (PEDOT) and different dopants (sodium dodecyl sulphate-SDS, tiron, 3-methylthiophene) were grown electrochemically from aqueous solutions such that constituents were deposited simultaneously onto substrate electrodes. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) revealed that the composite films consisted of nanoporous networks of SWCNTs coated with polymeric film. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that these composite films had similar electrochemical response rates to pure polymeric films but a lower resistance and much improved mechanical integrity. The negatively charged carbon nanotubes (CNTs) served as anionic dopant during the electropolymerization to synthesize polymer/CNTs composite films. The specific electrochemical capacitance of the composite films is a significantly greater value than that for pure polymer films prepared similarly.
The higher capacitance of the composite films results obviously from the contribution of the embedded SWCNTs that provide interconnected pathways for electrons through the SWCNTs and ions through the pore network or the direct interaction between the delocalised electrons on polymer chains and the SWCNTs.
Using these composite films, the modified electrodes with improved properties were obtained.
Development of in Situ Electrochemical Small-Angle Neutron Scattering (eSANS) for Simultaneous Structure and Redox Characterization of Nanoparticles
Authors: Prabhu Vivek , Reipa Vytas , Bonnesen Peter , Rondinone Adam J 
Published: February 2020

The demand for engineered nanomaterials in expanding research sectors, such as energy and healthcare, require materials with widely disparate physicochemical properties. The oxidation and reduction (redox) properties of nanomaterials are crucial for catalysis, matching semiconductor band gaps for photovoltaics, as well as toxicology, since they may cause oxidative stress by generating reactive-oxygen species. Optical spectroscopy analysis of molecular and nanomaterials undergoing redox reactions quantifies the electron transfer and energetics of the reaction via potential control and are the most common analytical techniques employed for this purpose. However, with conjugation to organic ligands and smaller, well-defined particle sizes, engineered nanomaterial redox characterization would benefit by techniques that provide nanometer sensitivity to nanoparticle core and ligand structure. We developed an in situ electrochemical small-angle neutron scattering (eSANS) method to measure simultaneously the redox properties and size, shape, and interactions of solution-dispersed nanomaterials [1]. By combining multi-step potentials and chronocoulometry readout with SANS, the structure and redox properties of engineered nanomaterials are followed, simultaneously in one experiment. Specifically, ZnO nanoparticles were examined as dilute dispersions in pH buffered deuterium oxide solutions under negative electrode potentials. The ZnO disk-shaped nanoparticles undergo an irreversible size transformation upon reduction at the vitreous carbon electrode. The decrease in average nanoparticle size near a current maximum shows the reduction reaction from ZnO to Zn occurs. The eSANS method provides nanometer scale sensitivity to the nanoparticle size and shape changes due to an electrochemical reaction that is crucial to understand in energy, healthcare, and other applications. These experiments utilized the EQ-SANS beamline at the Spallation Neutron Source, Oak Ridge National Laboratory that uniquely provides the ability to follow the redox kinetics under quasi-stationary potential step-scans. The methodology, contrast variation, and scattering properties of the micro and nanoporous carbon electrodes will also be described.
[1] V.M. Prabhu and V. Reipa, J. Phys. Chem. Lett. 3, 646 (2012)
Improving Selectivity on Ge CMP Applications
Authors: Karagoz Ayse , Basim G. Bahar 
Published: February 2020

In this study, slurry formulations are evaluated to enhance selectivity for germanium silica planarization systems. Initial selectivity analyses were studied by material removal rate responses measured at a single particle-surface level through atomic force microscopy (AFM) wear tests using both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-CTAB) surfactants at their sub-micelle and above critical micelle concentrations (CMC) as a function of pH and oxidizer concentration [1]. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality [2]. The surfactant adsorption characteristics were studied through surface wettability (measured by contact angle technique) and FTIR analyses. It was determined that the very strong or loose self-assembled surfactant structures can help obtain selectivity on the silica/germanium systems and good defectivity control with a sufficient material removal rate values yet the surface charge of the wafer and the hydrophobic nature of the germanium surface add to the complex surface assembly of the surfactant systems. In addition, since the slurry stability is necessary to prevent unacceptable levels of surface roughness and defects, the impact of adding surfactants on particle-particle interactions is investigated in the paper.
References:

Vakarelski I. U., Brown, S.C, Basim G.B, Rabinovich, Y. I., and Moudgil B.M., "Tailoring Silica Nanotribology for CMP Slurry Optimization: Ca2+ Cation Competition in C12TAB Mediated Lubrication", ACS Applied Materials & Interfaces, Vol. 2, No 4, pp. 1228-1235, 2010.

Basim, G.B., Vakarelski, I.U. Karagoz, A. Chen, L., “Surfactant Mediated Slurry Formulations for Ge CMP Applications” MRS Proceedings, MRS Spring Meeting, San Francisco, CA, April 2013, V. 1560, DOI http://dx.doi.org/10.1557/opl.2013.971.
(Invited) Material Engineering for 7nm FinFETs
Authors: Moroz Victor , Huang Joanne , Choi Munkang , Smith Lee 
Published: February 2020

Recently, several enabling technologies have become available for integrating non-Si channels on Si wafers, including HKMG with acceptable trap densities, aspect ratio trapping, and low temperature epitaxy with in-situ doping. This considerably broadens the list of potential candidate materials for the 7nm technology node in search of exceeding performance of Si FinFETs.
The search for the alternative channel materials is often motivated by high levels of carrier mobility in bulk material. Some promising demonstrations have been done with long channel transistors. However, the bulk carrier mobility is not relevant for performance of the short channel transistors. The target channel length for the 7nm node is about 15 nm, with most of the carriers exhibiting ballistic transport without experiencing scattering events when moving from source to drain. The ballistic transport favors materials with lighter effective carrier mass in terms of the driving current strength. On the flip side, such materials exhibit higher off-state leakage currents via band-to-band tunneling and direct source-to-drain tunneling mechanisms. So, instead of being guided by the bulk carrier mobility numbers, a more appropriate approach is to evaluate the trade-off between the on-state and the off-state current levels for the particular combination of material properties and transistor design rules.
In this work, we assume that the process-related issues such as defects can be resolved over time and focus on performance of defect-free materials, with performance determined by fundamental material properties. This way, we can get the upper bound on performance for each candidate material and see if it is worth pursuing in terms of struggling through laborious process integration.
Besides the on-state and off-state currents, several other key metrics are included into the trade-off analysis, such as self-heating and the ability to withstand and dissipate the heat, and parasitic R and C of the MOL.
The comparative analysis of several candidate channel materials is performed considering four technology flavors: HP, SP, and LP logic, and the I/O transistors. The appropriate modeling methodologies are introduced to cover these materials and the target design rules.
Back Gate Bias Stressing on Extremely Thin SOI (ETSOI) MOSFETs with Gate Last Process Integration
Authors: Tang Zhaoyun , Tang Bo , Zhao Lichuan , Wang Guilei , Xu Jing , Xu Yefeng , Wang Hongli , Wang Dahai , Li Junfeng , Yan Jiang , Zhao Chao 
Published: February 2020

Full depleted extremely thin SOI (ETSOI) is viewed as a promising device due to its excellent immunity to short channel effect (SCE) especially with applying of back gate bias stressing. In this paper, SOI transistors fabricated with gate last process scheme with thin channel layers of 4 to 11nm are provided with superior device performance. For a given gate length less than 30nm, DIBL and Swing are achieved with 40mV/V and 78mV/Dec respectively with stressing of back gate bias. Threshold voltage can be tuned within range of 0.8 volts (Vdd=-0.05v). It is large enough for adjusting device performance. Also, from our results, it is shown that device with thicker channel layer of 11nm are more sensitive to back gate bias comparing with that with thinner channel layer of 4nm. It demonstrates electrical characteristic of ETSOI with thicker channel layer is propitious to be adjusted, while that is more convergent with thinner channel layer.
Figure.1. shows the detail integration flow of ETSOI with HKMG and TEM of cross section of gate structure. In Fig. 2, Id-Vg curves for different channel thickness are plotted. It can be seen that shift of voltage with thicker channel layer of 11nm is larger than that with thinner channel layer of 4nm. Fig. 3 displays Vt difference under back gate bias stressing for different channel thickness.
In conclusion, we have successfully fabricated extremely thin SOI (ETSOI) devices with both HK and MG last integration scheme. Excellent device performances are achieved and back gate bias stressing on device characteristic is analyzed. With thicker channel layers, devices are more sensitive to back gate bias, while with thinner channel layers; devices are more convergent for electrical characteristic.

References

[1] K. Cheng, etc. in IEDM Tech. Dig., Dec. 2012, pp. 419-422.
[2] A. Ohata, etc. IEEE Electron Device Lett., vol. 33, no. 3, pp. 348–350, March. 2012.
[3] A. Majumdar, etc. IEEE Electron Device Lett., vol. 30, no. 4, pp. 413–415, Apr. 2009.

[4] A. Majumdar, etc. IEEE Trans. Electron
Devices, vol. 56, no. 10, pp. 2270–2276, Oct. 2009..

[5] A. Khakifirooz, etc. IEEE Electron Device Lett., vol. 33, no. 2, pp. 149–151, Feb. 2012.
Process Parameters Effect on Deep Silicon Etching for High Density Capacitor Structure
Authors: Meng Lingkuan , Yan Jiang , Li Chunlong , Li Junjie , Hong Peizhen , Luo Jun , Li Junfeng , Zhao Chao 
Published: February 2020

In deep silicon etching process, there have been many investigations on etching rate. However, only few published papers mentioned the sidewall roughness, which is a critical issue for NMES/MEMS application. In this work, we encountered a special phenomenon: sidewall damage, which was firstly observed during deep silicon etching. Various process parameters such as chamber pressure, bias power, passivation gas flow and etch time have been investigated using a conventional two steps Bosch process for high density Metal-insulator-metal (MIM) capacitor application. During the etching, obvious sidewall damage can be observed in the etched trench sidewall. It can be noted its starting depth has a close dependence on process parameters such as chamber pressure and bias power, which play a significant role influencing etching profile and trench depth. At a lower pressure, a smooth sidewall without any damage can be achieved. With pressure increasing above a certain value, sidewall damage has almost occurred in the full trench, which will lead a series of severe issues such as poor conformal deposition of high-k insulation film, discontinuity of the electrode layer, and reliability failures in MIM capacitor structure.
On the other hand, at a given pressure, bias power has a direct effect on etching profile and sidewall damage. As bias power increases, etching profile becomes more negative from vertical one. In particular, sidewall damage is not located in certain depth range but distributed in almost whole trench sidewall and, multi-bowing profile can be seen with increasing etching depth.
According to the experimental results, an etching mechanism has been presented to explain the etching phenomena by the ion angular distribution function (IADF) fundamental. Finally, by optimizing process parameters, a perfectly smooth profile without any sidewall damage can be obtained having an aspect ratio as high as 30 with 5μm width.
Monolithic Entangled Photon Sources Using Second Order Optical Nonlinearities
Authors: Helmy Amr S 
Published: February 2020

Entangled photon sources play a pivotal role in most of the optical systems that utilize quantum effects. Those include quantum key distribution, quantum computing, metrology, sensing and imaging. Photon pair generation using spontaneous parametric down conversion (SPDC) is one of the most popular routes for producing entangled photons. While SPDC has become more popular, the creation of entangled photon pairs in a degree of freedom, such as polarization, is more challenging. The difficulty is related in no small part to the birefringence of the structure where the generation takes place. Birefringence results in distinguishing information that hinders the production of entanglement in the platforms where SPDC has been most popular including ferroelectric crystals.
Despite this limitation, entangled sources have been realized in bulk crystals via well designed interference techniques, which often include additional compensating optics. As the boundaries of optical quantum information science continue to be extended, multi-photon entanglement is now required. Solutions based on SPDC have been attempted, and while some outstanding results have been achieved, the interferometers and compensation procedures become increasingly complex as the size of the entangled state grows. Such scalability and stability issues are directly addressed by integrated entangled photon sources, and while still in their infancy, they promise to help a great deal towards the practical utilization and the production of entanglement on a larger scale.
Semiconductors are an ideal platform to fabricate such integrated entangled photon sources. Recently, it was demonstrated that the gallium-arsenide (GaAs) based Bragg refection waveguide (BRW), could efficiently produce photon pairs via SPDC. This platfrom was shown to have a distinct advantage over other semiconductor sources, due largely to its monolithic architecture and its layered epitaxy, which underpins many photonic devices. In this work we demonstrate yet another advantage: the intrinsic capability of the BRW to directly produce polarization entangled photon pairs, without any additional interferometry, spectral filtering, compensation or post-selection. Not only do we show that the BRW can produce entangled photons, but we wish to emphasize that the traditional compensation and interferometric methods used to create entanglement, which presumably would have occurred on chip, may no longer be necessary. Our experimental results confirm that the BRW has the potential to be one of the very first self-contained integrated room temperature resources of entanglement.
In this talk various approaches for utilizing SPDC processes in various integration platforms will be discussed. The root cause of entanglement generation is the lack of birefringence in these material systems, which otherwise makes exact phase matching impossible in bulk crystals. Because of this, cross-polarized photons propagate at almost identical group velocities, making off-chip path compensation unnecessary.
Correlation Between CD Bias and Fwhm Bandwidth on Immersion Exposure Systems
Authors: Jung Juyoung , Roh Yonghan 
Published: February 2020

Immersion lithography has been developed with great speed. This technology moved to volume production of memory devices about 7 years ago. As immersion lithography developed, various and unexpected problems occurred under 30nm devices. In the act of investigating these problems, it was discovered correlation between Critical Dimension (CD) bias and full-width-at-half-maximum (FWHM). The relationship between wavelength and focus are well known issue [Fig. 1]. Also deviation of wavelength was become a crucial factor on CD bias. These similar phenomena will be frequently happened despite meeting the specification. Therefore this correlation will be able to be a solution for the similar cases.
CD bias issue was occurred in 2x nm node production. This phenomenon was expected an aberration problem, presented equation like below. For improving CD bias, chromatic distortion (aberration) had to be minimized by reducing (λ-λo). (λ-λo) is a kind of bandwidth. Also it is called a FWHM.
Correlation between aberration and laser wavelength

δx(x) = (λ-λo) x dSx/dλ + (λ-λo) x3 dE/dλ

where, [δx(x) : chromatic distortion]
[(λ-λo) : laser wavelength deviation]
[dSx/dλ, dE/dλ : distortion coefficient]
[x : slit position]
The test of narrowing FWHM is done successfully from 0.3pm to 0.25 pm [Fig. 2]. As a result it is obtained better aberration values (coma Z7_0 0.7 nm à 0.4 nm). and CD bias issue was under controlled by E95 (FWHM). Although It is impossible for revealing the exact information about CD in this paper, this problem still occurred similar phenomena. CD bias issue was not easy to solve, However equation and simulations [Fig. 3, Fig. 4] could be explained clearly. Wavelength deviation caused best focus shift, which led to CD bias issue.
References
[1] Armen Kroyan et al., “Effects of 95% Integral vs. FWHM Bandwidth Specifications on Lithographic Imaging” Proc. SPIE Vol. 4346(2001)
[2] Kevin Huggins et al., “Effects of laser bandwidth on OPE in a modern lithography tool.” Proc. of SPIE Vol. 6154(2006)
[3] R. C. Peng et al., “Effects of laser bandwidth on Iso-Dense Bias and Line End Shortening at sub-micron process nodes” Proc. of SPIE Vol. 6520, 65203S, (2007)