bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Development of CMOS-MEMS Cointegrated Pressure Sensor Using Minimal Fab Process
Authors: Liu Yongxun , Akita Ippei , Matsukawa Takashi , Tanaka Hiroyuki , Koga Kazuhiro , Nemoto Kazumasa , Khumpuang Sommawan , Nagao Masayoshi , Morita Yukinori , Hara Shiro
Published: May 2020

The Minimal Fab concept was proposed in 2008 to produce low-volume customized devices with a low investment cost [1]. The different points of Minimal Fab compared with those of the conventional Mega Fab are as follows. (a) Wafer size is half-inch (12.5 mm), (b) the transferring and processing of the wafer are performed with a cleanliness level identical to that of a super clean room, and (c) the machine used compact dimensions of 144 cm height, 30 cm width, and 45 cm depth. Since the proposal of the Minimal Fab concept, many Minimal Fab machines and Minimal Fab processes have been developed actively for the fabrication of CMOS integrated circuits [2, 3]. However, the Minimal Fab process for MEMS sensor fabrications has not been developed sufficiently. In this work, we develop the CMOS-MEMS cointegrated process using the Minimal Fab deep-RIE and mask aligner. By using the developed process, we also fabricate and characterize the digital type CMOS-MEMS pressure sensor. The pressure sensing element in the CMOS-MEMS pressure sensor is the CMOS ring oscillator with the longitudinal PMOSFETs located at the edge areas of a thin circular diaphragm. In the device fabrication, we used (100) oriented half-inch SOI wafers, and the source-drain (SD) regions of the MOSFETs were patterned along with the <110> direction to effectively utilize mechanical stress induced drain current variations. As the gate material, we used a 30-nm-thick PVD-TiN layer to obtain a suitable logic gate threshold voltage of the CMOS invertors. The circular diaphragm was fabricated using Minimal Fab mask aligner and deep-RIE. It was confirmed that the oscillation frequency changes from 360 to 400 kHz by changing pressures from -40 to +40 kPa in the fabricated CMOS-MEMS cointegrated pressure sensor chip. The developed CMOS-MEMS pressure sensor is suitable for the application to the battery drive IoT sensor systems owing to its low power consumption. [1] S. Hara et al., J. Jpn. Precis. Eng., vol. 77, no. 3, p. 249, 2011. [2] Y. X. Liu et al., Jpn. J. Appl. Phys. 56, p. 06GG01-1. [3] Y. X. Liu et al., J. Appl. Phys. 57, p. 06HD03-1.
Evidence of High Energy Storage Density and Break Down Voltage in the Eco-Friendly Eu-Substituted K0.5Bi0.5TiO3 Dielectric Ceramics
Authors: Banerjee Krishnarjun , Asthana Saket
Published: May 2020

The significance of the energy storage and transfer device in the modern and upcoming era is undeniable. To tackle the energy scarcity in the coming era, the research and development on the various renewable energy sources and the storage materials are extensively propelled. The device with good energy storage density is required for the perfect utilization of the electricity which is produced by renewable energy sources. The ferroelectric material can be an effective choice as an energy storage material, because of its high dielectric constant, high break down voltage, and more thermal & mechanical stability. Usually, it is observed that the lead based anti-ferroelectric materials have the better energy storage density than the lead free normal ferroelectric material. The global requirement and the banning of lead based material thrust the exploration of the lead free materials with higher energy storage density. Several lead-based and lead-free A and/or B–site substituted perovskite type (ABO3 type structure) ferroelectric materials are developed to gain high energy storage density. As far as the environment is concerned, in this work the energy storage property is investigated on the optimized eco-friendly 4 mol % Eu3+ substituted K0.5Bi0.5TiO3. At the room temperature the obtained recoverable energy storage density is 0.84J/cm3 which is comparable to some the lead based solid solutions. The room temperature polarization vs. electric field curve of this compound is shown in figure 1.

Figure 1

. Room temperature polarization vs. electric filed curve of 4 mol % Eu3+ substituted K0.5Bi0.5TiO3. The discharge path of the hysteresis loop is shown in red color.

The recoverable energy storage density is calculated from area under the discharge curve of the hysteresis loop (shown in red color) and the polarization axis in the first quadrant. From the figure, it can be observed that this material shows a high break down strength of 131kV/cm, which enhances the applicability of the material in the presence of high electric field. Apart from the ferroelectric study, the temperature dependent dielectric study of the material has been carried out. The recoverable energy storage density and high break down strength of this lead free material shows its suitability for fabricating energy storage material.

Figure 1
(Invited) Engineering the Structure and Properties of Nanocrystals to Design Electronic Devices and Sensors
Authors: Oh Soong Ju
Published: May 2020

Colloidal nanocrystals have been shown to be promising materials for device applications because of their unique size-dependent properties and solution processability. We present general methods to engineer the electronic, optoelectronic, electromechanical, and electrothermal properties of nanocrystals through their surface and interface engineering. Unconventional materials design and strategy are introduced to fabricate semiconducting devices such as field effect transistors, photodetectors, solar cells, and wearable sensors including temperature sensors, strain sensors, and pressure sensors. This technique provides a pathway for designing low cost, high performance, and multifunctional electronic skins or wearable devices.
Electrical Conductivity and Relaxation Behavior Studies of Corning Glass By Impedance Spectroscopy
Authors: Streltsova Elena , Cai Ling , Rubendall Jacob
Published: May 2020

Impedance Spectroscopy was applied to study conductivity and dielectric relaxation behavior of Corning’s glasses. The electrical behavior of several glass composition was studied over a wide range of frequency (1Hz -1MHz) and temperature (RT-500C). The relaxation time were calculated by analysis of electrical modulus. The calculated activation energy associated with dielectric relaxation and activation energy of dc conductivity are similar. The obtained values of conductivity confirm dependence of conductivity on number and mobility of ions at glass with different composition. With increasing conductivity, the relaxation time decrease. It was observed, that through entire temperature range, the dielectric relaxation is governed by the same mechanism.
Dynamic Observation of Electromigration in High Density Electroplated Nanotwinned Copper through in-Situ TEM
Authors: Shen Fang-Chun , Huang Chih-Yang , Wu Wen-Wei
Published: May 2020

Electromigration (EM) has become an important issue due to the revolution of scale-down devices in integrated circuit industry. Previous studies demonstrated that twin boundary could slow down EM; however, there was still less works discussing the relation between the density of nanotwin and EM in atomic resolution. The challenge would result from the disturbance of thermomigration (TM). In this study, the electroplated nanotwinned copper was annealed for higher thermal stability to prevent TM causing by Joule heating. By introducing high-density electroplated nanotwins into copper, the EM rate on a surface can be measured through in-situ TEM. Moreover, in-situ experiment also provides direct observation on dynamic evolution of the surface structure. The EM rate would be retarded at the triple points, which is significantly slower than previous researches. Furthermore, Cu atoms was gradually removed along (-111) when applying a current with a density of 104 A/cm2. With the observation of the structural variation and the calculated rate of EM on the surface, this study is expected to provide further insight into the EM mechanism and improve the reliability of metal interconnect design.

Figure 1
(Invited) Garnet-Based Hybrid Composite Electrolytes for the All-Solid-State Li-S Battery
Authors: Bag Sourav , Thangadurai Venkataraman
Published: May 2020

Lithium sulfur (Li-S) batteries have emerged as one of the most promising post LIBs technologies with a remarkably high theoretical energy density and abundance of elemental sulfur. Nonetheless, there are many problems associated with lithium sulfur batteries such as safety hazard due to lithium dendrite formation and fast capacity decay due to polysulfide dissolution effect.1 Solid electrolytes are promising to prevent lithium dendrite formation and polysulfide dissolution. Among different ceramic electrolytes garnet-type solid inorganic electrolytes are very promising because of its high ionic conductivity and stability with metallic lithium. But the high interfacial resistance with the electrode is the major bottleneck for the practical use of garnet electrolyte.2 However, polymer-based solid electrolytes possess low interfacial resistance but associated low ionic conductivity at room temperature is the biggest challenge for the utilization in solid-state-batteries.3

Recent research theme of Thangadurai group is mainly focused on garnet-type and polymer-garnet composite electrolytes for the practical utilization in all-solid-state Li batteries. Surface modifications of the garnet-type electrolytes and novel composite electrolytes developed in the laboratory have been successfully employed in all-solid-state-Li-S batteries even at room temperature. Fabrication of these electrolytes in bulk scale, characterizations, electrochemical properties and all-solid-state-Li-S battery performances will be discussed.

References:

1. Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Chem. Rev.
2014, 114, 11751-11787.

2. Han, X.; Gong, Y.; Fu, K.; He, X.; Hitz, G.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E.; Hu, L. Nat. Mater.
2016, 16, 572-579.

3. Zhou, C.; Bag, S.; Thangadurai, V. ACS Energy Lett.
2018, 3, 2181-2198.

4. Bag, S.; Zhou, C.; Kim, P.; Pol, V. G.; Thangadurai, V. Energy Storage Mater.
2019 (doi.org/10.1016/j.ensm.2019.08.019)
Insight into the Effect of LiNO3 Additive in High‐Voltage NCA Cathode with a Cylindrical 18650 Lithium-Metal Battery
Authors: Joraleechanchai Nattanon , Duangdangchote Salatan , Sawangphruk Montree
Published: May 2020

Lithium metal is an attractive anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g−1) and low density (0.59 g cm−3). Unfortunately, lithium metal itself faces huge problems including inhomogeneous lithium deposition, infinite volume expansion, increased polarization, and dendrite formation. To overcome these drawbacks, many researchers have employed LiNO3 additive in the ether-based electrolyte to modify the properties of the solid electrolyte interface (SEI) film formed on the lithium metal surface. The LiNO3 can improve an ionically conductive, dense, and stable SEI formation through Li stripping and plating. However, LiNO3 has low solubility in carbonate based. Thus, LiNO3 was applied as an additive in carbonate electrolyte using CuF2 as a dissolution promoter. Herein, we demonstrate carbonate electrolyte system using LiNO3 and CuF2 with different ratios in high‐voltage Ni‐rich cathode with a cylindrical shape (18650). To achieve fundamental understanding of the effect of electrolyte additive molecules on the SEI formation at the lithium anode, reactive molecular dynamic simulation (Reaxff) has been used to investigate the mechanism and property of the SEI layer on the lithium anode.
A Fast Charge/Discharge and Wide-Temperature Battery with Ultra-Thin Germanium Oxide Layer on 2D Mxene Matrix As Anode
Authors: Niu Junjie
Published: May 2020

In contrast to silicon, germanium shows an electrical conductivity of ~1.0 S m-1 that is 100 times higher than silicon, and a fast lithium ion diffusivity of 10-12 -10-8 cm2 s-1 that is 400 times faster than silicon, leading to a promising potential in rapid charge/discharge batteries. Similar as silicon, the large volume expansion upon lithiation/delithiation leads to capacity decay and thus poor cycling performance. The scalable production of complex nano-structures also pose a challenge. Recently MXene, a family of 2D transition-metal carbides, are attracting great interest in lithium-ion batteries due to their unique electrical, mechanical and electrochemical properties particularly with the high electrical conductivity. Here we present a novel 2D hybrid composite that is composed of 2D layered MXene as host covered with a thin layer of amorphous GeOx, which showed an improved rate capability as anode electrode in lithium ion batteries. The battery with hybrid composite as anode maintains 90% of the initial capacity with a coulombic efficiency of 99.4 % after charging/discharging 500 cycles at 0.5 C. A high capacity retention under 10.0 C and 20.0 C and a wide temperature between -40 ℃ and 80 ℃ was achieved. A full-cell battery paired with NMC as cathode also exhibited a high capacity.

Keywords: Germanium; MXene; High rate performance; Lithium ion batteries
(Invited) Silicon Nanocrystals for Optoelectronic Synaptic Devices
Authors: Pi Xiaodong
Published: May 2020

Nowadays neuromorphic computing is regarded as one of the most promising solutions to the Von Neumann bottleneck due to its high intelligence and low energy consumption. The development of neuromorphic computing critically depends on synaptic devices, which simulate biological synapses in neural systems. The incorporation of light into synaptic devices has been recently inspired by the exciting development of optogenetics in neuroscience. Although optically stimulated synaptic devices with electrical output have been realized, the use of light as the output of synaptic devices under electrical stimulation has not been demonstrated. This may impede the full optoelectronic integration of artificial neural systems for neuromorphic computing. In this talk I shall introduce our recent work on using light-emitting silicon nanocrystals (Si NCs) [1] to fabricate electroluminescent synaptic devices [2,3]. These devices exhibit a series of important synaptic functionalities, including paired-pulse facilitation (PPF), transition from short-term plasticity (STP) to long-term plasticity (LTP) and spike-timing-dependent plasticity (STDP). In the meantime, logic functions such as "AND", "OR", "NAND" and "NOR" can also be realized by using these electroluminescent synaptic devices.

References

Y. Ni, S. Zhou, S. Y. Zhao, W. B. Peng, D. Yang and X. D. Pi, Silicon nanocrystals: unfading silicon materials for optoelectronics, Materials Science & Engineering R 138, 85-117 (2019).

Y. Zhao, Y. Wang, W. Huang, H. Jin, P. W. Huang, H. Wang, K. Wang, D. S. Li, M. S. Xu, D. Yang and X. D. Pi, Developing near-infrared quantum-dot light-emitting diodes to mimic synaptic plasticity, Science China Materials 62, 1470–1478 (2019).

Y. Zhao, Z. Y. Ni, H. Tan, Y. Wang, H. Jin, T. X. Nie, M. S. Xu, X. D. Pi and D. Yang, Electroluminescent synaptic devices with logic functions, Nano Energy 54, 383-389 (2018).
(Invited) Photoelectrochemical Properties of All-Inorganic Core/Shell Silicon Quantum Dots
Authors: Fujii Minoru , Sugimoto Hiroshi
Published: May 2020

Silicon (Si) quantum dots (QDs) are an environmentally friendly nano-functional material potentially suitable for biophotonics applications. Recently, we have developed a new type of all-inorganic Si QDs that can be dispersed in water almost perfectly without organic ligands and exhibit size-dependent photoluminescence (PL) in the near-infrared range in water [1-2]. The unique property of the QDs arises from the unique structure achieved by simultaneous doping of boron (B) and phosphorus (P). The figure shows a typical transmission electron microscope (TEM) image of a B and P codoped Si QD [3]. The lattice fringe corresponds to {111} planes of crystalline Si. On the surface of the crystalline core, an amorphous shell is formed. The shell is composed of Si, B and P, the concentration of B and P being in the range from a few % to 10 at.%. The shell induces negative potential on the surface and prevents agglomeration of Si QDs in polar solvents by the electrostatic repulsion. To the ligand-free surface of codoped Si QDs, molecules in a solution can access easily, and thus a variety of charge-transfer-induced phenomena such as a photocatalytic effect and chemical doping are expected [4-5]. In a codoped Si QD, B and P are also doped in the crystalline core. Formation of donor and acceptor states in the band gap strongly modifies the luminescence property. Combination of the quantum size effect and the doping effect leads to the control of the luminescence energy in the range much wider than that of conventional Si QDs [6, 7]. By comparing the luminescence energy with those obtained by theoretical calculations, we estimate the number of active B and P pairs in a Si QD to be 2-10 depending on the doping concentration and the size. In the presentation, we will discuss the luminescence and photoelectrochemical properties, including photocatalytic hydrogen evolution, of the B and P codoped Si QDs.

References

[1] M. Fujii, H. Sugimoto, and S. Kano, Chem. Commun., Vol. 54, 4375 (2018).

[2] M. Fujii, H. Sugimoto, and K. Imakita, Nanotechnology, Vol. 27, 262001 (2016).

[3] H. Sugimoto, et al., Nanoscale, Vol. 10, 7357 (2018).

[4] T. Kojima, H. Sugimoto, and M. Fujii, J. Phys. Chem. C, Vol. 122, 1874 (2018).

[5] K. Inoue, T. Kojima, H. Sugimoto, and M. Fujii, J. Phys. Chem. C, Vol. 123, 1512. (2019).

[6] H. Sugimoto, et al., J. Phys. Chem. C, Vol. 117, 11850 (2013).

[7] H. Sugimoto, et al., Nano Letters, Vol. 18, 7282 (2018).

Figure 1
(Invited) Imaging the Dynamics of Energy-Harvesting Materials at the Nanoscale
Authors: Leite Marina S.
Published: May 2020

Halide perovskites for optoelectronics are often composed by micro- and nano-scale inhomogeneous constructs. Therefore, high spatial resolution characterization methods are required for mapping and quantifying their electrical behavior. In this talk I will present our latest developments on atomic force microscopy (AFM) methods to assess the dynamic physical and chemical processes that take once perovskite materials and photovoltaic devices are exposed to light. Briefly, we realize a 4D imaging method that enables mapping open-circuit voltage (Voc) changes with in real-time (16 seconds per scan), and at the nanoscale (< 50 nm in spatial resolution) based on illuminated Kelvin probe force microscopy (KPFM). Using this paradigm, we have demonstrated ion motion within a single nanoscale grain in MAPbI3 solar cells upon 1-sun illumination, which results in a residual Voc that lasts for several minutes even under dark conditions. For multi-cation structures, we found that Cs-based perovskites deliver fully reversible and stable nanoscale voltage response, in excellent agreement with macroscopic measurements. We correlate the Voc nanoscale maps with chemical imaging through nano-IR and discover that the local variations in voltage are related to the power conversion efficiency enhancement in KI-treated perovskite. The heterogeneity revealed in both the local electrical and chemical responses reveals that the KI additive migrates our of the perovskite films, yet surprisingly; does not affect device performance. Our functional imaging platform can be extended to other perovskite materials, including Pb-free options.
(Invited) Towards Tm2+ in Sialon Thin Films Grown by Sputtering Using the Gradient Deposition
Authors: Bosco Giacomo , van der Kolk Erik
Published: May 2020

There are different material candidates for efficient industry compatible luminescence solar concentrators to be used in electricity generating glass applications. Among them, divalent thulium (Tm2+) doping has been shown to have a high potential. It has been reported to have 65% absorption of the solar spectral range when in di-halide hosts, while showing no self-absorption and a relatively neutral colour [1]. These characteristics are possible because Tm2+ has a strong absorption from the UV up to about 900 nm. This absorption is generated by intense 4f
13 → 4f
125d
1 electronic transitions and a single emission line at 1140 nm, credited to the 2F5/2 → 2F7/2 transition of the 4f
13 configuration. However, this specific oxidation state of thulium is rather anomalous: so far it was only stabilized on di-halide crystals. These crystals are very hygroscopic in nature, therefore not sufficiently attractive for scaling up in industry standard thin film growth techniques. Thus, it is necessary to research on the possible extension in the list of materials able to host such a promising optically active element. However, the intrinsic complex nature of the lanthanide’s electronic structure has prevented a detailed understanding of the valence stability of its elements. Therefore, designing industry compatible hosts ensuring that such exotic ion is stable and capable of efficiently emitting NIR light is a challenging task.

In this work, I show the progress made so far towards unravelling the conditions for stabilization of the Tm2+ in industry compatible thin film materials – more specifically, thin film materials of the SiAlON family. I report recent results on Tm doped SiAlON thin films grown by combinatorial magnetron reactive sputtering. The gradient characterization method [2], developed at the TU Delft’s luminescence materials research group, was used in order to relate position dependent film composition – determined by energy dispersive x-ray spectroscopy – with local transmission, photoluminescence emission and excitation data. This singular approach makes it possible to retrieve a wide composition range in a smaller number of different films. These results are discussed upon the valence stability model of lanthanides of Dorenbos [3], and the model of impurity ionization adopted in solid state statistics.

References

[1] O. M. ten Kate, K. W. Krämer, and E. van der Kolk, “Efficient luminescent solar concentrators based on self-absorption free, Tm 2+ doped halides,” Sol. Energy Mater. Sol. Cells, vol. 140, pp. 115–120, Sep. 2015.

[2] E. P. J. Merkx and E. van der Kolk, “Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries,” ACS Comb. Sci., vol. 20, no. 11, pp. 595–601, Nov. 2018.

[3] P. Dorenbos, “Valence stability of lanthanide ions in inorganic compounds,” Chem.
Mater., vol. 17, no. 25, pp. 6452–6456, Dec. 2005.
(Invited) Lanthanide Doped Nanoparticles and Their Applications
Authors: Vetrone Fiorenzo
Published: May 2020

Since approximately 2000, lanthanide doped nanoparticles have received significant attention due to their interesting luminescent properties. At the core of this interest is their ability to convert near-infrared excitation light (typically 980 or 800 nm) to higher energies spanning the ultraviolet, visible and near-infrared regions of the spectrum through a multiphoton process known as upconversion. Upconversion differs from conventional multiphoton excitation in other materials where no real intermediate states are present necessitating the use of ultrafast lasers (in the femtosecond regime) for simultaneous excitation to the upper emitting state. The lanthanide ions possess a multitude of 4f electronic states that have long lifetimes (micro- to millisecond) thus act as population reservoirs in the upconversion process. Hence, upconversion occurs through real, long-lived intermediate states through a sequential photon absorption process. This eliminates the need for ultrafast excitation and as a result, upconversion can be observed using inexpensive, continuous wave diode lasers. Upconversion luminescence can be exploited for a number of applications in nanomedicine, theranostics, photovoltaics, photocatalysis, as well as many others.

While their upconversion luminescence has been studied in great detail, lanthanide doped nanoparticles can also emit in the near-infrared through a direct Stokes (down-shifted) luminescence process. Of particular importance is that these near-infrared emissions lie within the biological windows where biological tissues are optically transparent. For obvious reasons, a great deal of the work on the nanomedicine and theranostics applications of lanthanide doped nanoparticles has shifted to their near-infrared luminescence properties.

In this presentation, we will demonstrate the synthesis of these nanoparticles, establish how changing their nanoscale architecture can affect their luminescence properties (both upconversion and near-infrared), and discuss their potential applications, particularly in nanomedicine.
(Invited) Gap Nanowires with Twinning Superlattices: Structure, Optical Properties and Applications
Authors: Isik Goktas Nebile , Gupta Divyanshu , Rubel Oleg , LaPierre Ray R
Published: May 2020

Semiconductor nanowires (NWs) are a good candidate for future optoelectronic devices. However, the control of the essential parameters that determine the electronic and optical quality of NWs, such as crystal structure and incorporation of impurity dopants, are still challenging problems. Most III-V NWs exhibit crystal defects, which are typically randomly distributed zincblende twinning segments and stacking faults that can affect the optical and electrical properties of NW devices. The incorporation of intentional impurity dopants in NWs is important for the fabrication of p-n junctions and control of the electrical conductivity of NWs. The effect of Te and Be impurity dopant concentration on the crystal structure, surface roughness and optical properties of GaAs NWs will be presented. Four identical GaAs NW arrays were grown: an undoped sample (as a reference) and 6 samples with different Te and Be doping concentration. High resolution transmission electron microscopy (HRTEM) revealed an unusual superlattice twinning, with periodicity that became wider and more regular as the doping level increased. Twin boundaries in GaP are shown to act as an atomically narrow plane of wurtzite phase with a type-I homostructure band alignment. Twin boundaries and stacking faults (wider regions of the wurtzite phase) lead to the introduction of shallow trap states observed in photoluminescence studies. Controlling the surface roughness, the periodicity, and the width of twinning planes with doping concentration might open new possibilities for high efficiency NW-based thermoelectric devices, but also has wide implications for all NW devices.
(Invited) InGaAs/InP Quantum Well Nanowire Surface Emitting LEDs
Authors: Fu Lan
Published: May 2020

III-V compound semiconductor nanowires (NWs) have drawn much attention as nanoscale light sources for integrated photonics due to their nanoscale size, good optical properties and strain relaxation feature enabling the monolithic growth on lattice mismatched substrates. In particular, NWs grown by selective area epitaxy (SAE) technique have many advantages such as controllability of their size and position, high uniformity in diameter and length, as well as complementary metal-oxide-semiconductor (CMOS) process compatibility, facilitating their integration with Si based electronic technologies. With suitable wavelength ranging from 1.3 to 1.6 μm and lattice match of constituent materials, InGaAs/InP quantum wells (QWs) have been being widely used for optical communication applications. However there has been limited understanding on the growth of InGaAs/InP QWs in nanowire architecture and their application for lasers or LEDs. In this work, we present the study of the SAE growth of InGaAs/InP QW NW array by metalorganic chemical vapour deposition (MOCVD) technique, and the demonstration of both single and array nanowire LEDs with an in-depth investigation of their geometry related device properties.
Photophysical Properties and Applications of Exfoliated Near Infrared Fluorescent CaCuSi4O10 Nanosheets
Authors: Kruss Sebastian
Published: May 2020

Imaging in the near infrared range of the spectrum is beneficial due to reduced light scattering, absorption, toxicity and autofluorescence. However, there are only few near infrared fluorescent materials known and suitable for biomedical applications. Here, we exfoliate the near infrared fluorescent layered pigment CaCuSi4O10 (known as Egyptian Blue, EB) into nanosheets (EB-NS) v
ia tip sonication. Dimensions of the nanosheets decreased with sonication time < 20 nm in diameter and heights of single EB layers (around 1 nm). The near infrared fluorescence of EB and the fluorescence life-times at 910 nm are retained in EB-NS and the total fluorescence intensity scales with size. Furthermore, we demonstrate that EB-NS display ultra-high photostability (no bleaching) and are extremely bright compared to other nIR fluorophores. The versatility of EB-NS as nIR fluorophores for biological imaging is demonstrated by in vivo single-particle tracking and microrheology measurements in developing Drosophila embryos. Furthermore, EB-NS can be uptaken by plants and used for remote detection. In summary, we introduce 2D CaCuSi4O10 nanosheets as versatile material for nIR imaging of biological samples.
(Invited) Understanding the Role of Protein Corona on Oligonucleotide Recognition Efficiency in Fluorescent Flares
Authors: Wang Hao , Lee Ki-Bum , Fabris Laura
Published: May 2020

Nanoparticle-based biosensors are developed and implemented to address a wide range of biomedical questions in bioimaging, molecular diagnostics, targeted drug delivery and controlled release, or photothermal cancer therapy. In this respect, gold nanoparticles provide physicochemical and optical properties that make them particularly interesting. Their relevant, and often unique, plasmonic response has enabled their integration with various transduction modalities (e.g. colorimetric, fluorescence, Raman) and led to the development of extremely sensitive and selective detection platforms. Added advantages associated with gold nanoparticles are their excellent biocompatibility and low toxicity compared to some other nanomaterials (notably quantum dots and silver nanoparticles) when used for sensing and imaging purposes in vivo.

In recent years, the performance of gold nanoparticles in the biological milieu has attracted substantial interest. It is well known that, when employing nanoparticles in in vivo studies, proteins present in the biological environment contribute to opsonization, a process that leads to the recognition and attack by macrophages and systematic clearance. For in vitro applications, this process can affect instead the performance of the nanoparticle-based sensors, by reducing in particular sensitivity and selectivity. In both instances, the culprit is the rapid formation of a protein corona around the nanoparticle, which hinders the interaction of any responsive moiety conjugated to its surface with the target molecules present in the surrounding environment. In this talk, I will discuss how the formation of protein corona affects the response of fluorescent flares as they are employed to identify target oligonucleotides in solution. By monitoring the fluorescent response that originates upon hybridization of the nanoflares with their targets, we determined that protein corona, regardless of the identity of the proteins employed to mimic the biological environment, negatively impacts the hybridization dynamics, leading to a reduction in sensitivity by almost 20%, compared to the 2 nM LODs in the absence of corona. We also observed that the presence of protein corona leads to reduced resistance to nucleases, with different effects that depend on the size of the specific proteins, leading us to hypothesize the importance of steric hindrance. Finally, and surprisingly, we observed that polyethylene glycol (PEG) functionalization does not substantially improve the performance of the flares, with further reduced sensitivity due to the lower number of recognition moieties that can be accommodated on the nanoparticle’s surface when PEG is also introduced. We believe that these results will offer further quantitative insight useful for the development of in vivo and in vitro probes based on gold nanoparticles.
(Invited) Isolating an Individual Ion Emitter and Light-Induced Tunneling Upconversion
Authors: Gordon Reuven
Published: May 2020

This talk will review two recent discoveries made in my group.

Single Photon Emitters: Intrigued by the promise of single-photon quantum technologies, many have studied the properties of single ion defect emitters, particularly lanthanides in a crystal matrix (including praseodymium, cerium, and erbium). I will report on a way of reliably isolating individual erbium ion emitters in nanocrystals with the potential for 100% individual emitter yield in post-selection. We used a nanoplasmonic (metal nanostructure) aperture optical tweezer to reliably isolate individual erbium ion emitters in individually trapped NaYF4 nanocrystals. The nanoplasmonic aperture solved two major problems: (1) it enhanced the emission rate so that single ions could be detected reliably in a short time, and (2) it isolated the single Er containing nanocrystal from the other nanocrystals in solution. This new demonstration follows our recently published work showing 400× increased emission using the nanoapertures.

Light-Induced Upconversion Emission: Upconverted light from nanostructured metal surfaces can be produced by harmonic generation and multi-photon luminescence; however, these are very weak processes and require extremely high field intensities to produce a measurable signal. Here we report on bright emission, 5 orders of magnitude greater than harmonic generation, that can be seen from metal tunnel junctions due to light-induced inelastic tunneling. Like inelastic tunneling light emission, which was recently reported to have 2% conversion efficiency per tunneling event, the emission wavelength recorded varies with the local electric field applied; however, here the field is from a 1560 nm femtosecond pulsed laser source. Finite-difference time-domain simulations of the experimental conditions show the local field is sufficient to generate tunneling-based inelastic light emission in the visible regime. This phenomenon is promising for producing ultrafast upconverted light emission with higher efficiency than conventional nonlinear processes.
(Invited) Nanoscale Llight Management Using Three-Dimensional Scanning Near-Field Optical Microscopy
Authors: Fanchini Giovanni
Published: May 2020

In this talk, we will present an overview of aperture and apertureless type scanning near-field optical microscopy (SNOM) techniques that have been developed for the characterization of photonics-grade nanoscale materials, with a focus on three-dimensional (3D) SNOM methods. 3D SNOM has been undertaken to image the local distribution (within ~100 nm of the surface) of the electromagnetic radiation scattered by random and deterministic arrays of

metal nanostructures or photonic crystal waveguides. Individual metal nanoparticles and metal nanoparticle arrays exhibit unique effects under light illumination, including plasmon resonance and waveguiding properties, which can be directly investigated using 3D-SNOM. In the second part of this article, we will review a few applications in which 3D-SNOM has proven to be useful for designing and understanding specific nano-optoelectronic structures and photonic materials. Examples will include the analysis of the nano-optical response phonetic crystal waveguides, aperture antennae and metal nanoparticle arrays, as well as the design of plasmonic solar cells incorporating random arrays of copper nanoparticles as an optical absorption enhancement layer, and the use of 3D-SNOM to probe multiple components of the electric and magnetic near-fields without requiring specially designed probe tips. A common denominator of these examples is the added value provided by 3D-SNOM in predicting the properties-performance relationship of nanostructured systems in photonics grade materials.
Manufacturing Impact on Electrochemical and Mechanical Performance of NMC Cathodes Via Mesoscale Simulation
Authors: Ferraro Mark E. , Trembacki Bradley L. , Brunini Victor E. , Noble David R. , Roberts Scott A.
Published: May 2020

Lithium-ion battery performance is determined by numerous coupled multi-physics effects which can be tuned through various manufacturing methods. Electrode calendering pressure can compress local mesostructures, shortening conductive pathways and introducing contact points where mechanical stresses manifest. The addition of a secondary conductive binder phase alters ionic and electronic conduction pathways, limits available surface area for reaction, and buffers mechanical contacts. Coupled physics simulation can visualize localized behaviors that arise from altering these macroscale conditions.

Here, we use a mesoscale simulation approach to explore the influence of manufacturing conditions on the performance of an NMC333 half-cell. Image-based particle representations are combined with the Conformal Decomposition Finite Element Mesh (CDFEM) algorithm to provide a conformal, solvable mesh for coupled electrochemical/mechanical simulations. Resolution at this particle scale allows analysis of localized phenomena dependent on particle size, shape, and local mesostructure. Our discussion will detail the limiting physics and variations across domains of four different calendering pressures (0, 300, 600, 2000 bar) and conductive binder fraction (90, 92, 94, 96wt% active material). Per-particle analyses will quantify differences between mesostructures and discuss how local variations influence macroscale properties like cell pressure, effective conductivity, and the discharge curve. Furthermore, we will discuss the statistical effects of domain sample selection on electrode-scale behaviors. This mesoscale analysis allows us to isolate the most significant limiting factors for discharge performance, providing suggestions for future battery design.

Sandia National Laboratories is a multi-mission 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-NA0003525.
(Invited) The Mutual Roles of the Plasma and Liquid in Plasma Electrolysis
Authors: Go David B.
Published: May 2020

Plasma electrolysis can be roughly described as replacing one of the solid electrodes in a conventional electrolytic cell with a plasma (i.e., gas discharge) such that charge transfer oxidation or reduction reactions occur at a plasma-liquid interface rather than a solid-liquid interface. One of the most promising aspects of these systems is the chemistry induced in the liquid by the plasma, ranging from the reduction of metal cations to produce colloidal nanoparticles to the oxidation of organic compounds for water remediation. However, because the plasma itself is a dynamic medium, the liquid also has an impact on plasma properties and behavior. Ultimately, the physics and chemistry of both the plasma and liquid are tightly coupled and mutually dependent, and unraveling these interactions is important for understanding, designing, and optimizing these systems. This talk will overview the efforts of our team to understand these roles using a variety of experimental measurements, theory, and simulations. Topics will include the in situ detection of the solvated electron injected by a plasma, the efficiency of those electrons in driving chemistry, and a recent theoretical description of plasma self-organization on the liquid surface.
Unveiling the Mechanisms Leading to the ‘Green’ Synthesis of Metal Oxide Quantum Dots By Plasma Induced Non-Equilibrium Electrochemistry (PINE)
Authors: Padmanaban Dilli babu , McGlynn Ruairi James , Maguire Paul , Mariotti Davide
Published: May 2020

The synthesis of a range of metal oxide quantum dots (QDs) has been demonstrated in the past few years utilizing plasma-induced non-equilibrium electrochemistry (PiNE).1
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4These reports have also shown important features of these QDs with benefits for energy and other applications. The synthesis process has shown a generalized approach for metal oxide QDs that include Cu, Mo, Zn, Ni, Mn and Co. In this contribution we will first overview the opportunities offered by this technique for metal oxides. We will then report on an in-depth investigation to understand the mechanisms and reaction pathways leading to the formation of QDs. This will be mainly based on the synthesis of CuO QDs (< 5 nm diameter), however we will also attempt to extrapolate our findings to understand the synthesis of other metal oxides, highlighting any differences. In particular, we carried out extensive characterization of both the QDs as well as the electrolyte. In addition to materials characterization techniques, we used Fourier transform infra-red spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass (GC-MS) spectroscopy. Further, measurements for pH and other trace products were also carried out as well as optical emission spectroscopy. Overall our work discloses important general aspects of plasma-liquid interactions, in particular when ethanol is used. The specific synthesis of CuO QDs follows a ‘green’ synthesis cycle that only produces water as by-product with traces of hydrogen peroxide and isopropanol.

Reference

(1) Velusamy, T.; Liguori, A.; Macias-Montero, M.; Padmanaban, D. B.; Carolan, D.; Gherardi, M.; Colombo, V.; Maguire, P.; Svrcek, V.; Mariotti, D. Plasma Process. Polym.
2017, 14 (7), 1600224.

(2) Ni, C.; Carolan, D.; Rocks, C.; Hui, J.; Fang, Z.; Padmanaban, D. B.; Ni, J.; Xie, D.; Maguire, P.; Irvine, J. T. S.; Mariotti, D. Green Chem.
2018, 20 (9), 2101–2109.

(3) Ni, C.; Carolan, D.; Hui, J.; Rocks, C.; Padmanaban, D.; Ni, J.; Xie, D.; Fang, Z.; Irvine, J.; Maguire, P.; Mariotti, D. Cryst. Growth Des.
2019, 19 (9), 5249–5257.

(4) Chakrabarti, S.; Carolan, D.; Alessi, B.; Maguire, P.; Svrcek, V.; Mariotti, D. Nanoscale Adv.
2019.
(Invited) Electrochemical Characterization of the Interface between Atmospheric Noble Gas Plasma Jet and Aqueous Solution
Authors: Oldham H.E. (Trey) , Thimsen Elijah
Published: May 2020

Elucidation of general features of the interface between atmospheric pressure plasma jets and aqueous solutions would be beneficial to environmental, agricultural and biomedical applications. Such fundamental descriptions are critically important to design process chemistries and scale-up production. In this presentation, our recent efforts towards that end will be discussed. The focus of the talk will be on free jets of low temperature radiofrequency (RF) plasma generated using noble gas in contact with water, in contrast to the often used two-electrode configuration with e.g. micro-plasmas. Experiments will be presented in support of a perspective that views the plasma-liquid interface as a boundary condition that locally constrains the reduction potential, which can be controlled using parameters such as the plasma gas composition, applied RF power, and jet stand-off distance. A unique spatial distribution of the reduction potential that develops to maintain charge neutrality in the aqueous solution will be presented. The consequences for process design and scale-up will be expanded upon.
Engineering of MnO2 Materials at the Nanoscale By PE-CVD for Photoactivated Technologies
Authors: Bigiani Lorenzo , Barreca Davide , Gasparotto Alberto , Altantzis Thomas , Štangar Urška Lavrenčič , Alessi Bruno , Padmanaban Dilli Babu , Mariotti Davide , Maccato Chiara
Published: May 2020

Photoactivated processes have been widely recognized as cost effective and environmentally friendly routes for both renewable energy generation and purification/cleaning technologies. Great attention has been devoted to the degradation of persistent pollutants in effluent wastewaters, such as dyes from textile, paper and pharmaceutical industries, into harmless products. In addition, increasing efforts have been focused on photoinduced anti-fogging and self-cleaning applications promoted by suitable functional systems endowed with tuneable hydrophobic/hydrophilic properties.

In this context, the present work [1] is focused on the development of supported MnO2-based nanomaterials as platforms for the above mentioned photo assisted applications.

The selected materials were grown on fluorine-doped tin oxide substrates using plasma enhanced-chemical vapor deposition (PE-CVD) between 100 and 400 °C. This technique allows to gain a fine tuning on the resulting material chemico-physical properties, which, in turn, affect the resulting functional performances. PE-CVD experiments yielded the formation β-MnO2 characterized not only by different hierarchical morphologies (from dendritic structures to quasi-1D nanosystems), but also by a concomitant tailoring of the fluorine content, optical absorptions and band gap values as a function of the adopted growth temperature.

Preliminary photo-induced hydrophilicity/photocatalytic functional tests highlighted the possibility of finely tailoring MnO2 nanomaterial performances, thanks to the interplay between their nano-organization, F content and optical absorption capabilities. In addition, the use of Vis illumination instead of UV one did not result in an appreciable performance decrease, paving the way to the use of natural sunlight to activate the target processes. The obtained results, which, to the best of our knowledge, have no precedents to date on the target materials, open challenging perspectives for the development of multi-functional photocatalysts for self-cleaning and antifogging applications, as well as for wastewater treatment.

References

[1] D. Barreca et al. Nanoscale 2019, 11, 98-108
Preparation of Plasmonic Cu Nanoparticles By Pulsed Laser Ablation in Liquid and Their Characterization
Authors: Wang Yong , Ma Dongling , Chaker Mohamed
Published: May 2020

Photocatalysis plays a pivotal role in solar energy transferring into usable energy. In recent years, visible light driven photocatalysts have been attracted more attention due to the broadened solar absorption wavelength. In this regard, the plasmonic photocatalysts based on gold (Au), silver (Ag) and copper (Cu) can strongly absorb visible light due to their localized surface plasmon resonance (LSPR). Compared with most studied Ag and Au nanoparticles, Cu is a low-cost plasmonic material owing to its higher earth abundance. However, the difficulty in fabricating chemically stable Cu nanoparticles limits their application. Here, the colloidal Cu nanoparticles were fabricated via pulsed laser ablation in liquid (PLAL) by Nd:YAG laser (1064 nm) and the size and optical properties of the nanoparticles were characterized by transmission electron microscopy and UV-visible spectrophotometry, respectively. The effect of fabrication parameters, such as laser fluence, ablation time, organic solvent and ablation time was further investigated. In addition, the composition and stability of the as-prepared plasmonic Cu nanoparticle was also studied. The as-prepared plasmonic Cu nanoparticle exhibit strong LSPR absorption peak in the visible region, which is beneficial to the application in photocatalysis, solar energy harvesting, optoelectronics, and biomedical technologies.