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Abstract

HfZrOx-based Si n-/p-type ferroelectric field-effect transistors (n/pFEFETs) were investigated from 300 to 82 K with pulse measurements, which disclosed device physics at low temperatures. Moreover, FEFET shows extremely improved performance (read-after-write latency < 100 ns and write endurance $10^{{10}}$ cycles with no device degradation) at 82 K. Even the lower write voltage is feasible at 82 K than at 300 K although the coercive field increases. The enhancement is attributed to frozen trap sites and increased coercive field at 82 K. Our work not only shows a deep understanding of device physics but also proposes that FEFET could be a promising cold memory.

We investigated the role of graphene interfaces in strengthening and toughening of the Cu-graphene nanocomposite by a combination of in situtransmission electron microscopy (TEM) deformation and molecular dynamics (MD) simulations. In situTEM directly showed that dislocation plasticity is strongly confined within single Cu grains by the graphene interfaces and grain boundaries. The weak Cu-graphene interfacial bonding induces stress decoupling, which results in independent plastic deformation of each Cu layer. As confirmed by the MD simulation, the localized deformation made by such constrained dislocation plasticity results in the nucleation and growth of voids at the graphene interface, which acts as a precursor for crack. The graphene interfaces also effectively block crack propagation promoted by easy delamination of Cu layers dissipating the elastic strain energy. The toughening mechanisms revealed by the present study will provide valuable insights into the optimization of the mechanical properties of metal–graphene nanolayered composites.

Graphical abstract:

The atomic layer deposition (ALD) of Ru using a metal–organic precursor, tricarbonyl(trimethylenemethane)ruthenium [Ru(TMM)(CO)3] and O2as a reactant is reported. The high vapor pressure, thermal stability, and relatively small ligands of the precursor facilitate efficient ALD. Typical self-limiting growth and an ALD temperature window of 220–260 °C are observed along with significantly high growth per cycle (GPC) (∼1.7 Å) and short incubation cycles (∼6) at 220 °C. Density functional theory calculations indicate that the high growth rate and self-limiting behavior can be attributed to the characteristics of the trimethylenemethane ligand. The as-grown polycrystalline films (average grain size ∼20 nm and negligible impurities) were evident from plan-view transmission electron microscopy. The variation in film resistivity with increasing film thickness and deposition temperature was investigated with and without annealing. Films deposited at 260 °C show low resistivity (∼12.9 μΩ cm), which further decreases (∼9.8 μΩ cm) postannealing at 500 °C. A thin Ru film is successfully deposited with 100% step-coverage on a dual-trench structure having an aspect ratio of ∼6.3 (minimum width: ∼15 nm). The interfacial adhesion energy measured using the four-point bending test exceeds 7 J m–2, regardless of the dielectric material and annealing treatment. The Ru precursor permits enhanced nucleation and GPC at relatively low deposition temperatures to construct high-quality Ru films with significantly low resistivity using simple, plasma-free techniques, and is suitable for the fabrication of emerging Ru films to replace Cu-based interconnects.

In this study, a polymer/metal nanowire nanocomposite employing a hard-core-soft-matrix design is developed, demonstrating high strength, recoverability, and electrical conductivity. Incorporation of conductive fillers in PDMS has been of interest, and here a new design in the form of nanocomposite consisting of polyvinyl alcohol/silver nanowire 3D porous composite that is then infiltrated with soft PDMS matrix is demonstrated. The vertically aligned freeze-dried structure within the composite exhibited a remarkable strength increase of up to 3.5 times compared to PDMS alone. The incorporation of hard and soft phases with 3D interfaces effectively hindered fracture propagation within the composite thereby greatly enhancing the stretchability; PVA+AgNW/PDMS nanocomposite demonstrated an excellent recoverability 82.7%. In addition, the silver nanowire network provides sufficient conductivity with small filler concentration of 0.47 vol % that makes PVA+AgNW/PDMS nanocomposite a compelling choice for flexible electronics application requiring a combination of electrical conductivity, high strength, and excellent recoverability.

Traditionally, the manipulation of contact mechanisms has been adopted as the primary strategy to tailor the friction properties of surfaces. On the contrary, the detaching process involving the local deformation and failure at the interface has been considered relatively less important. Here, we present a new approach toward the friction control of amorphous carbon through the plasticity and resultant transition of deformation mode on nanopatterned surfaces. Depending on the topography of the nanopatterns, the mechanical responses of the surfaces alter from elastic fracture to plastic flow, through which the friction coefficient changes by a factor of 5 without manipulation of the intrinsic structure of the material.

Although metal–phenolic species have emerged as one of the versatile material-independent-coating materials, providing attractive tools for interface engineering, mechanistic understanding of their film formation and growth still remains largely unexplored. Especially, the anions have been overlooked despite their high concentration in the coating solution. Considering that the anions are critical in the reactivity of metal–organic complex and the formation and/or property of functional materials, we investigated the anionic effects on the characteristics of film formation, such as film thickness and properties, in the Fe3+–tannic acid coating. We found that the film characteristics were strongly dictated by the counteranions (e.g., SO42–, Cl–, and Br–) of the Fe3+ion. Specifically, the film thickness and properties (i.e., mechanical modulus, permeability, and stability) followed the reversed anionic Hofmeister series (Br–> Cl–> SO42–). Mechanistic studies suggested that more chaotropic anions, such as Br–, might induce a more widely extended structure of the Fe3+–TA complexes in the coating solution, leading to thicker, harder, but more porous films. The reversed anionic Hofmeister effect was further confirmed by the additive effects of various sodium salts (NaF, NaCl, NaBr, and NaClO4).

Although graphene has considerable potential as a next-generation transparent conducting electrode (TCE) material owing to its excellent optical transparency and flexibility, its electrical properties require further improvement for industrial application. This study reports a pathway of doping graphene by selective atomic layer deposition (ALD) of metals to elevate the electrical conductivity of graphene. Introduction of a novel Pt precursor [dimethyl(N,N-dimethyl-3-butene-1-amine-N)platinum(II); C8H19NPt; DDAP] facilitates a low-temperature (165 °C) process. The sheet resistance (Rs) of graphene is reduced significantly from 471 to 86.8 Ω sq–1after 200 cycles of Pt ALD, while the optical transmittance at 550 nm (T) is maintained above 90% up to 200 cycles due to the selective growth of Pt on the defects of graphene. Furthermore, comprehensive analysis, including metal (Ru, Pt, and Ni) ALD on graphene, metal (Ru, Pt, Ni, Au, and Co) evaporation on graphene, and change in the ALD chemicals, demonstrates that ALD allows efficient graphene doping and the oxygen affinity of the metal is one of the key properties for efficient graphene doping. Finally, Pt ALD is applied to a multilayer graphene to further reduce Rsdown to 75.8 Ω sq–1yet to be highly transparent (T:87.3%) after 200 cycles. In summary, the selective ALD of metals opens a way of improving the electrical properties of graphene to a level required for the industrial TCE application and has the potential to promote development of other types of functional metal–graphene composites.

Deposition providing precise control of the film thickness, low deposition temperature, and noncorrosive byproducts is essential for the efficient fabrication of barrier layers in semiconductor devices. Here, molybdenum nitride (MoNx) is deposited for Cu diffusion barrier application at a relatively low temperature (180–300 °C) by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo(CO)6] and ammonia gas (NH3). The density functional theory calculations indicate favorable thermodynamics during the chemisorption of Mo(CO)6on −NH2-terminated Si clusters at 200 °C, confirming the suitability of Mo(CO)6for ALD. However, the films deposited beyond the ALD temperature window are of similar importance though decomposition-induced growth of the film is evident; nevertheless, other advantages exist (e.g., higher growth rate and improved film characteristics). Furthermore, a few experiments using NH3plasma as a reactant show further scope for this process. The as-grown MoNxfilm using thermal ALD is mostly amorphous with significant O impurity. Poorly structured nanocrystalline h-MoN and cubic Mo2N phase are formed in the film above 225 °C. These phases are converted into the crystalline cubic Mo2N phase upon annealing at higher temperature (500–700 °C) in a hydrogen atmosphere. The resistivity of the MoNxfilms decreases sharply with deposition temperature and is significantly reduced further upon post-annealing. The properties of the as-deposited and annealed films are characterized in detail by secondary-ion mass spectroscopy and X-ray photoelectron spectroscopy. The barrier properties against Cu diffusion for the as-deposited thin films (less than 10 nm) grown at 225 and 275 °C are analyzed using ex situ X-ray diffraction (XRD) and electrical impedance spectroscopy (EIS). EIS helps to determine the failure of the MoNxbarrier layer qualitatively by comparing different EIS spectra obtained after annealing at different temperatures. Both XRD and EIS analyses show that the ALD-MoNxfilm deposited at the higher ALD temperature makes a better Cu diffusion barrier layer. This could be attributed to the higher density of the ALD MoNxfilm grown at 275 °C compared with that deposited at 225 °C.

Flexible and stretchable electrochromic supercapacitor systems are widely considered as promising multifunctional energy storage devices that eliminate the need for an external power source. Nevertheless, the performance of conventional designs deteriorates significantly as a result of electrode/electrolyte exposure to atmosphere as well as mechanical deformations for the case of flexible systems. In this study, we suggest an all-transparent stretchable electrochromic supercapacitor device with ultrastable performance, which consists of Au/Ag core–shell nanowire-embedded polydimethylsiloxane (PDMS), bistacked WO3nanotube/PEDOT:PSS, and polyacrylamide (PAAm)-based hydrogel electrolyte. Au/Ag core–shell nanowire-embedded PDMS integrated with PAAm-based hydrogel electrolyte prevents Ag oxidation and dehydration while maintaining ionic and electrical conductivity at high voltage even after 16 days of exposure to ambient conditions and under application of mechanical strains in both tensile and bending conditions. WO3nanotube/PEDOT:PSS bistacked active materials maintain high electrochemical–electrochromic performance even under mechanical deformations. Maximum specific capacitance of 471.0 F g–1was obtained with a 92.9% capacity retention even after 50 000 charge–discharge cycles. In addition, high coloration efficiency of 83.9 cm2C–1was shown to be due to the dual coloration and pseudocapacitor characteristics of the WO3nanotube and PEDOT:PSS thin layer.

Abstract

Binderless, additiveless Si electrode design is developed where a nanoporous ZnO matrix is coated on a Si microparticle electrode to accommodate extreme Si volume expansion and facilitate stable electrochemical cycling. The conversion reaction of nanoporous ZnO forms an ionically and electrically conductive matrix of metallic Zn embedded in Li2O that surrounds the Si microparticles. Upon lithiation, the porous Li2O/Zn matrix expands with Si, preventing extensive pulverization, while Zn serves as active material to form LixZn to further enhance capacity. Electrodes with a Si mass loading of 1.5 mg/cm2were fabricated, and a high initial capacity of ∼3900 mAh/g was achieved with an excellent reversible capacity of ∼1500 mAh/g (areal capacity ∼1.7 mAh/cm2) beyond 200 cycles. A high first-cycle Coulombic efficiency was obtained owing to the conversion reaction of nanoporous ZnO, which is a notable feature in comparison to conventional Si anodes. Ex situanalyses confirmed that the nanoporous ZnO coating maintained the coalescence of SiMPs throughout extended cycling. Therefore, the Li2O/Zn matrix derived from conversion-reacted nanoporous ZnO acted as an effective buffer to lithiation-induced stresses from volume expansion and served as a binder-like matrix that contributed to the overall electrode capacity and stability.

Polymer nanocomposites with inclusion of ceramic nanofillers have relatively high yield strength, elastic moduli, and toughness that therefore are widely used as functional coating and films for optoelectronic applications. Although the mechanical properties are enhanced with increasing the fraction of nanofiller inclusion, there generally is an upper limit on the amount of nanofiller inclusion because the aggregation of the fillers in the polymer matrix, which typically occurs, degrades the mechanical and/or optical performances above 5 vol % of inclusions. Here, we demonstrate an unconventional polymer nanocomposite composed of a uniformly distributed three-dimensional (3D) continuous ceramic nanofillers, which allows for extremely high loading (∼19 vol %) in the polymer matrix without any concern of aggregation and loss in transparency. The fabrication strategy involves conformal deposition of Al2O3nanolayer with a precise control in thickness that ranges from 12 to 84 nm on a 3D nanostructured porous polymer matrix followed by filling the pores with the same type of polymer. The 3D continuous Al2O3nanolayers embedded in the matrix with extremely high filler rate of 19.17 vol % improve compressive strength by 142% compared to the pure epoxy without Al2O3filler, and this value is in agreement with theoretically predicted strength through the rule of mixture. These 3D nanocomposites show superb transparency in the visible (>85% at 600 nm) and near-IR (>90% at 1 μm) regions and improved heat dissipation beyond that of conventional Al2O3dispersed nanocomposites with similar filler loading of 15.11 vol % due to the existence of a continuous thermal conduction path through the oxide network.

Herein, a new methodology for solution-processed ZnO fabrication on Ag nanowire network electrode via combustion reaction is reported, where the amount of heat emitted during combustion was minimized by controlling the reaction temperature to avoid damaging the underlying Ag nanowires. The degree of participation of acetylacetones, which are volatile fuels in the combustion reaction, was found to vary with the reaction temperature, as revealed by thermogravimetric and compositional analyses. An optimized processing temperature of 180 °C was chosen to successfully fabricate a combustion-reacted ZnO and Ag nanowire hybrid electrode with a sheet resistance of 30 Ω/sq and transmittance of 87%. A combustion-reacted ZnO on Ag nanowire hybrid structure was demonstrated as an efficient transparent electrode and electron transport layer for the PTB7-Th-based polymer solar cells. The superior electrical conductivity of combustion-reacted ZnO, compared to that of conventional sol–gel ZnO, increased the external quantum efficiency over the entire absorption range, whereas a unique light scattering effect due to the presence of nanopores in the combustion-derived ZnO further enhanced the external quantum efficiency in the 450–550 nm wavelength range. A power conversion efficiency of 8.48% was demonstrated for the PTB7-Th-based polymer solar cell with the use of a combustion-reacted ZnO/Ag NW hybrid transparent electrode.

In this study, Li[NixCoyMnz]O2cathode composition library was fabricated using combinatorial methodology and characterized using nanoindentation to create a mechanical properties database as a function of Li[NixCoyMnz]O2composition. A single sputter deposition from LiCoO2, LiNiO2, and LiMn2O4compound targets resulted in a composition range of 3–44 at.% Co, 20–80 at.% Ni, and 5–50 at.% Mn. Young’s modulus and hardness values were evaluated before and after charge–discharge cycles, and a strong dependency of the mechanical properties on composition was found; Mn-rich composition showed highest retention of its mechanical properties whereas the properties degraded more significantly for the Ni-rich composition. Electrochemical performance was analyzed and compared to mechanical properties at various Li[NixCoyMnz]O2compositions and a strong correlation between enhanced mechanical properties retention leading to superior discharge capacity retention was found for the Mn-rich compositions. Li[Ni0.33Co0.30Mn0.34]O2composition showed optimized electrochemical and mechanical properties, where it retained 38% and 50% of its Young’s modulus and hardness after cycling while demonstrating 91% discharge capacity retention after 20 cycles at 1 C-rate.

Fatigue behavior of Ag nanowire network subjected to different degrees of compressive bending strain was investigated and compared against the results from tensile bending strain. Ag nanowire network under compression showed excellent reliability showing only a 6.0% increase in fractional resistance at 400,000 cycles, which is superior in comparison to that under tensile strain. The Ag nanowire network under compression was shown to cause buckling of the Ag nanowires, which then relaxed the elastic strain imposed on the Ag nanowire that led to enhanced reliability. The buckled nanowire, however, can cause strain localization especially with small radius of bending, thus causing the failure to occur within the length of individual nanowires unlike in the case of nanowire network under tensile strain that was shown to fail at the junctions with high stress concentrations.

Sn possesses three times higher capacity in comparison to graphite anode (372 mAhg–1) that makes it a promising candidate for enhanced performance Li ion batteries. Contrary to Si, Sn is compliant and ductile in nature and thus is expected to readily relax the Li diffusion-induced stresses. The low melting point of Sn additionally allows for stress relaxations from time-dependent or creep deformations even at room temperature. In this study, numerical modeling is used to reveal the significance of plasticity and creep-based stress relaxations in the Sn working electrode. The maximum elastic tensile hoop stresses for 1 μm micropillar size with 1Ccharging rate conditions reduces down from ∼1 GPa to ∼200 MPa when Sn is allowed to plastically deform at a yield strength of ∼150 MPa. After experimentally determining the creep response of Sn micropillars, creep deformations are incorporated in numerical modeling to show that the maximum tensile hoop stress is further reduced to ∼0.45 MPa under the same conditions. Lastly, the Li-induced stresses are analyzed for different micropillar sizes to evaluate the critical size to prevent fracture, which is determined to be ∼5.3 μm for C/10 charging rate, which is significantly larger than that in Si.

To reduce the cost of the Cu(In,Ga)Se2(CIGS) solar cells while maximizing the efficiency, we report the use of an Ag nanowires (NWs) + poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid transparent electrode, which was deposited using all-solution-processed, low-cost, scalable methods. This is the first demonstration of an Ag NWs + PEDOT:PSS transparent electrode applied to CIGS solar cells. The spin-coated 10-nm-thick PEDOT:PSS conducting polymer layer in our hybrid electrode functioned as a filler of empty space of an electrostatically sprayed Ag NW network. Coating of PEDOT:PSS on the Ag NW network resulted in an increase in the short-circuit current from 15.4 to 26.5 mA/cm2, but the open-circuit voltage and shunt resistance still needed to be improved. The limited open-circuit voltage was found to be due to interfacial recombination that is due to the ineffective hole-blocking ability of the CdS film. To suppress the interfacial recombination between Ag NWs and the CdS film, a Zn(S,O,OH) film was introduced as a hole-blocking layer between the CdS film and Ag NW network. The open-circuit voltage of the cell sharply improved from 0.35 to 0.6 V, which resulted in the best cell efficiency of 11.6%.

Carbon-nanotube (CNT)-based textile supercapacitors with MnO2nanoparticles have excellent power and energy densities, but MnO2nanoparticles can be delaminated during charge–discharge cycles, which results in significant degradation in capacitance. In this study, polypyrrole conductive polymer was coated on top of MnO2nanoparticles that are deposited on CNT textile supercapacitor to prevent delamination of MnO2nanoparticles. An increase of 38% in electrochemical energy capacity to 461 F/g was observed, while cyclic reliability also improved, as 93.8% of energy capacity was retained over 10 000 cycles. Energy density and power density were measured to be 31.1 Wh/kg and 22.1 kW/kg, respectively. An in situ electrochemical–mechanical study revealed that polypyrrole–MnO2-coated CNT textile supercapacitor can retain 98.5% of its initial energy capacity upon application of 21% tensile strain and showed no observable energy storage capacity change upon application of 13% bending strain. After imposing cyclic bending of 750 000 cycles, the capacitance was retained to 96.3%. Therefore, the results from this study confirmed for the first time that the polypyrrole–MnO2-coated CNT textile can reliably operate with high energy and power densities with in situ application of both tensile and bending strains.

Hydro-electric technology has gathered much attention by the virtue of water as the energy source. However, the low energy density of this technology severely limits its practical use. Here, we demonstrate a PEDOT:PSS-based transpiration-driven electrokinetic power generator (p-TEPG) that enables the utilization of a wider variety of real-world water resources for maximizing energy generation efficiencies. In addition to the conventional electrical double layer on the material surface, the p-TEPG builds an additional potential difference in the polymer matrix by the selective penetration of cations into the matrix that contains sulfonate functional groups. p-TEPG exhibits 80–250% higher energy density than carbon-based TEPG at the same resistance. Moreover, seawater produced enhanced volumetric energy/power densities (34.36 mJ cm−3and 44.70 μW cm−3) and areal energy/power densities (410 μJ cm−2and 0.45 μW cm−2), respectively, compared to DI water on a single p-TEPG device, which is sufficient to charge electrical energy storage systems and directly operate low-powered electronic.

Ag nanowire transparent electrode has excellent transmittance and sheet resistance, yet its optical haze still needs to be improved in order for it to be suitable for display applications. Ag nanowires are known to have high haze because of the geometry of the nanowire and the high light scattering characteristic of the Ag. In this study, a Au-coated Ag nanowire structure was proposed to reduce the haze, where a thin layer of Au was coated on the surface of the Ag nanowires using a mild [Au(en)2]Cl3galvanic displacement reaction. The mild galvanic exchange allowed for a thin layer of Au coating on the Ag nanowires with minimal truncation of the nanowire, where the average length and the diameter were 13.0 μm and 60 nm, respectively. The Au-coated Ag nanowires were suspended in methanol and then electrostatically sprayed on a flexible polycarbonate substrate that revealed a clear reduction in haze with a 2–4% increase in total transmittance, sheet resistance ranges of 80–90%, and 8.8–36.8 Ohm/sq. Finite difference time domain simulations were conducted for Au-coated Ag nanowires that indicated a significant reduction in the average scattering from 1 to 0.69 for Au layer thicknesses of 0–10 nm.

In this work, a modified polyol synthesis by adding KBr and by replacing the AgCl with NaCl seed was used to obtain high quality silver nanowires with long aspect ratios with an average length of 13.5 μm in length and 62.5 nm in diameter. The Ag nanowires suspended in methanol solution after removing any unwanted particles using a glass filter system were then deposited on a flexible polycarbonate substrate using an electrostatic spray system. Transmittance of 92.1% at wavelength of 550 nm with sheet resistance of 20 Ω/sq and haze of 4.9% were measured for the electrostatic sprayed Ag nanowire transparent electrode.

Abstract

Abstract

The kinetic study of the nitrogen dissolution was investigated. An isotope exchange technique is employed as a method for measuring the rate of nitrogen dissolution into the molten steel and the effects of O, S, C, Mn, and B addition on surface reaction have been considered at 1873 K.

Metal–ceramic nanolayered composites have been reported to have high strength because of their effective confinement of dislocations at interfaces; however, this unfortunately results in unstable deformation due to the brittleness of the ceramic layer. This study explores the deformation behavior of a metal–ceramic nanolayered composite in which the ceramic layer thickness is varied to examine the effect of brittle-to-ductile transition of the ceramic layer. The thickness of AZO, which is theoretically expected to be ductile, is first fixed at 9 nm while varying the metal thickness. For further comparison, 150 nm Ag/120 nm AZO is studied, where the AZO layer is expected to be brittle. In-situ SEM pillar compression show stable deformation for samples with 9 nm thick AZO, in which co-deformation of metal and ceramic is confirmed by TEM analysis. A systematic increase in strength is observed with reduction of Ag thickness with stable plastic deformation for nanolayered composite with AZO thickness of 9 nm. For the 150 nm Ag/120 nm AZO, unstable deformation is observed in which brittle fracturing of the AZO layer leads to reduction in flow stresses or strain softening. Finite element analysis shows that the stresses in the Ag and the AZO layers reach the stresses required for co-deformation.

Piezoelectric materials are suitable for haptic technology as they can convert mechanical stimuli into electrical signals and vice-versa. However, owing to their disadvantageous mechanical properties such as brittleness (in ceramics) and a low piezoelectric coefficient (in polymers), their application in haptic technology remains challenging. In this paper, we introduce a truss-like 3D hollow nanostructure using zinc oxide (ZnO) that exhibits a drastically improved elastic strain limit while maintaining a piezoelectric coefficient similar to that of single-crystal ZnO. The ZnO hollow nanostructure was fabricated using proximity field nanopatterning (PnP) and atomic layer deposition (ALD) at four different processing temperatures. The piezoelectric characteristics were analyzed through dual AC resonance tracking piezoresponse force microscopy (PFM), and the piezoelectric coefficient was measured to be up to 9.2 pm/V. The nanopillar compression test result showed that the measured elastic strain limit of approximately 10% was at least 3 times greater than the previously reported value. The extended elastic limit of the 3D hollow structure was further supported by finite element simulations. The ZnO hollow nanostructure shows excellent potential for its application to enhanced haptic devices, which mimic the human sense of touch.

Sn is a promising Li ion battery anode with high theoretical capacity, but it can easily pulverize due to repeated application of extreme volumetric strain of 260% during cycling. Sn is a low melting point metal with low modulus and therefore has previously been proposed to be a fracture resistant anode due to its the ability to relax stresses via plasticity and creep deformations. In this study, intrinsic mechanical properties of lithiated Sn at various stages in the lithiation were evaluated using nanoindentation experiments using a special setup. In order to avoid oxidation of the highly reactive lithiated Sn, nanoindentation was performed on specimens submerged in a mineral oil bath. After careful calibration, hardness and modulus of different phases of lithiated Sn were evaluated. With an increase in the lithium content, both the modulus and hardness of the lithiated Sn decreased, as expected, where the modulus and hardness are 28.6 GPa and 0.37 GPa, respectively, for fully lithiated Sn (Li22Sn5) and 58.0 GPa and 0.77 GPa, respectively, for unlithiated Sn. This is the first report on the mechanical properties of lithiated Sn, which is expected to be of importance in theoretical analysis of the diffusion induced stresses in Sn anodes.

Use of nanoscale architecturing that exhibits superior strength-to-weight ratio has been of recent interest, and here we demonstrate a bulk fabrication of a fully recoverable, ultralight 3D porous composite with high strength composed of Ag nanowire/cellulose nanofiber using a freeze-casting method. A one-step process for highly efficient bulk formation of 3D porous structure via ice crystal formation followed by sublimation was demonstrated that can overcome the cost and scalability associated with lithography methods. 3D porous composite with controlled geometry was fabricated by controlling the nucleation and growth kinetics of ice formation that resulted in highly anisotropic compressive strength and resilience that depends on the wall orientations and composition of composite wall. Strength of the 3D porous composite increased with an increase in the Ag nanowire content as the deformation transitioned from bending dominant toward stretch dominant behavior for the case of vertically aligned walls, and an optimized concentration of Ag nanowires resulted in the compressive strength of 100 kPa at a relative density of 0.96%, which has 1.5 times higher strength when normalized by the material density (2.3 ± 0.2 MPa⋅cm3/g) in comparison to that of metal microlattice (1.7 MPa⋅cm3/g) fabricated by lithography methods. Horizontally oriented 3D porous structure interestingly showed a fully reversible deformation while also maintaining sufficient conductivity that makes this new material well-suited for a variety of flexible electronics applications.

Thin films of yttria-stabilized zirconia (Y2O3-stabilized ZrO2, YSZ) with various columnar grain sizes are successfully fabricated by combining a post-annealed seed layer and a successively deposited effective layer by pulsed laser deposition (PLD). As a result, YSZ thin films of different columnar grain sizes (column diameters of ∼15 nm, ∼40 nm, and ∼190 nm) are obtained with identical fabrication parameters except for the seed layer to engineer the grain size. According to analyses of the physical properties, the variation in the grain size induces differences not only in the grain boundary density, but also the strain state in each sample. These changes in physical properties are considered to affect the electrical property of the thin films in a combined way. Measurements of the cross-plane electrical conductivities of the YSZ thin films reveal that the electrical conductivity of the YSZ thin film increases up to 2 times as the columnar grain size increases. The present study provides intelligent and effective method for the design and manipulation of the microstructure of oxide thin films, thus enabling investigations into the correlated properties of interest.

Occasionally, in volume device manufacturing, a large number of particles may be generated on cleaned Si wafers. Surface (ionic, organic and/or metallic) contamination is generally suspected. However, conventional chemical analysis techniques for contamination are generally not able to distinguish between Si wafers with good and poor particle performance. No suspicious chemicals and elements were detected from any wafers regardless of characterization techniques. Surface photovoltage (SPV) measurement barely showed the differences between wafers with good and poor particle performance. Multiwavelength room temperature photoluminescence (RTPL) showed significant differences in intensity between them, indicating the presence of surface quality variations.

This study examined the dimensional effects on the channel strain in transistor structures with epitaxial Si1-xCxstressors embedded in the source/drain region using both nanobeam diffraction and finite element simulations. The sizes of the gate and source/drain exerted a strong influence on the channel strain but in opposite directions: While declining linearly with decreasing source/drain length, the channel strain increases at an escalating rate with decreasing gate length. For source/drain elevation, its effects on the channel strain were found to be quite limited to the top surface region; however, this elevation method could be more effective for short-channel transistors.