Effective Chemical Lift-Off for Air-Tunnel GaN on a Trapezoid-Patterned Sapphire Substrate.

We fabricated an air-tunnel structure between a gallium nitride (GaN) layer and trapezoid-patterned sapphire substrate (TPSS) through the in situ carbonization of a photoresist layer to enable rapid chemical lift-off (CLO). A trapezoid-shaped PSS was used, which is advantageous for epitaxial growth on the upper c-plane when forming an air tunnel between the substrate and GaN layer. The upper c-plane of the TPSS was exposed during carbonization.

Selective-Area Growth Mechanism of GaN Microrods on a Plateau Patterned Substrate.

This study provides experimental evidence regarding the mechanism of gallium nitride (GaN) selective-area growth (SAG) on a polished plateau-patterned sapphire substrate (PP-PSS), on which aluminum nitride (AlN) buffer layers are deposited under the same deposition conditions. The SAG of GaN was only observed on the plateau region of the PP-PSS, irrespective of the number of growth cycles. Indirect samples deposited on the bare c-plane substrate were prepared to determine the difference between the AlN buffer layers in the plateau region and silicon oxide (SiO2).

Effect of Multiple Reflows on the Interfacial Reactions and Mechanical Properties of an Sn-0.5Cu-Al(Si) Solder and a Cu Substrate.

In this study, the interfacial reactions and mechanical properties of solder joints after multiple reflows were observed to evaluate the applicability of the developed materials for high-temperature soldering for automotive electronic components. The microstructural changes and mechanical properties of Sn-Cu solders regarding Al(Si) addition and the number of reflows were investigated to determine their reliability under high heat and strong vibrations. Using differential scanning calorimetry, the melting points were measured to be approximately 227, 230, and 231 °C for the SC07 solder, SC-0.

Plasma-Assisted Surface Modification on the Electrode Interface for Flexible Fiber-Shaped Zn-Polyaniline Batteries.

A novel flexible fiber-shaped zinc-polyaniline battery (FZPB) is proposed to enhance the electrochemical performance, mass loading, and stability of polyaniline cathodes. To this end, electron-cyclotron-resonance oxygen plasma-modified carbon fibers are employed. During plasma treatment, on the carbon-fiber surface, O plasma breaks the C-C, C-H, and C-N bonds to form C radicals, while the O molecules are broken down to reactive oxygen species (O, O, O, and O).

Selective TiO Nanolayer Coating by Polydopamine Modification for Highly Stable Ni-Rich Layered Oxides.

Ni-rich layered oxides are promising cathode materials for developing high-energy lithium-ion batteries. To overcome the major challenge of surface degradation, a TiO surface coating based on polydopamine (PDA) modification was investigated in this study. The PDA precoating layer had abundant OH catechol groups, which attracted Ti(OEt) molecules in ethanol solvent and contributed towards obtaining a uniform TiO nanolayer after calcination.

In-Depth TEM Investigation on Structural Inhomogeneity within a Primary Li Ni Co Al O Particle: Origin of Capacity Decay during High-Rate Discharge.

The structural stability of cathode materials during electrochemical reactions, in particular, under high-rate discharge, is pertinent to the design and development of new electrode materials. This study investigates the structural inhomogeneity that develops within a single LiNi Co Al O (NCA83) particle during a fast discharging process under different cutoff voltages. Some of the NCA83 particles discharged from a high cutoff voltage (4.

Correction: Coaxial-nanostructured MnFeO nanoparticles on polydopamine-coated MWCNT for anode materials in rechargeable batteries.

Correction for 'Coaxial-nanostructured MnFe2O4 nanoparticles on polydopamine-coated MWCNT for anode materials in rechargeable batteries' by Hyeongwoo Kim et al., Nanoscale, 2018, 10, 18949-18960.

Coaxial-nanostructured MnFeO nanoparticles on polydopamine-coated MWCNT for anode materials in rechargeable batteries.

MnFe2O4@PDA-coated MWCNT coaxial nanocables are successfully designed via a simple one-pot process by utilizing the adhesion property of polydopamine (PDA) with cations in aqueous solutions and employing a modified co-precipitation synthesis at a low temperature. The incorporation of the PDA coating layer on the MWCNT leads to the well-dispersed state of the MWCNTs in the aqueous solution due to the hydrophilic functional group of the PDA coating layer. In addition, the catechol-based functional group of the PDA coating layer effectively anchors the Mn and Fe ions from the aqueous solution before the co-precipitation process, eventually resulting in the preferential and homogeneous formation of MnFe2O4 nanoparticles on the MWCNT.

Conducting Polymer Coating on a High-Voltage Cathode Based on Soft Chemistry Approach toward Improving Battery Performance.

The surface of a 5 V class LiNiMnO particle is modified with poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer by utilizing the hydrophobic characteristics of the 3,4-ethylenedioxythiophene (EDOT) monomer and the tail group of cetyl trimethyl ammonium bromide (CTAB) surfactants, in addition to the electrostatic attraction between cationic CTAB surfactant and cathode materials with a negative ζ potential in aqueous solution. With this novel concept, we design and prepare a uniform EDOT monomer layer on the cathode materials, and chemical polymerization of the EDOT coating layer is then carried out to achieve PEDOT-coated cathode materials via a simple one-pot preparation process. This uniform conducting polymer layer provides notable improvement in the power characteristics of electrodes, and stable electrochemical performance can be obtained especially at severe operating conditions such as the fully charged state and elevated temperatures owing to the successful suppression of the side reaction between the oxide particle and the electrolyte as well as the suppression of Mn dissolution from the oxide material.

One-Step Catalytic Synthesis of CuO/Cu2O in a Graphitized Porous C Matrix Derived from the Cu-Based Metal-Organic Framework for Li- and Na-Ion Batteries.

The hybrid composite electrode comprising CuO and Cu2O micronanoparticles in a highly graphitized porous C matrix (CuO/Cu2O-GPC) has a rational design and is a favorable approach to increasing the rate capability and reversible capacity of metal oxide negative materials for Li- and Na-ion batteries. CuO/Cu2O-GPC is synthesized through a Cu-based metal-organic framework via a one-step thermal transformation process. The electrochemical performances of the CuO/Cu2O-GPC negative electrode in Li- and Na-ion batteries are systematically studied and exhibit excellent capacities of 887.

Electrochemical Characteristics of Pyrolytic Carbon Coated Silicon for Anode Materials of Lithium Ion Batteries.

Pyrolytic carbon coated silicon is prepared and employ it as an anode material for lithium secondary batteries. The pyrolytic carbon coating of silicon with sucrose precursor not only provides a suitable carbon matrix but also suppresses the breaking away of Si from the current collector during the insertion and extraction of Li+. The increase of disordered carbon content leads to the increase of discharge capacity retention.

Oxidation-resistant hybrid metal oxides/metal nanodots/silver nanowires for high performance flexible transparent heaters.

Despite its excellent optical, electrical, mechanical, and thermal performances, a silver nanowire (AgNW)-based transparent conducting heater (TCH) still demonstrates several drawbacks such as facile nanowire breakdown on application of a high DC voltage, easy oxidation when exposed to harsh environments, leading to increased surface resistivity, and high resistance among wire junctions causing nonhomogeneous temperature profiles. To overcome these issues, the AgNW was hybridized with other transparent heating materials made of fluorine-doped tin oxide (FTO) thin films and NiCr nanodots (FTO/NiCr/AgNW). The dispersed NiCr nanodots (∼50 nm) and FTO thin films (∼20 nm) electrically bridge the nanowire junctions leading to a decreased sheet resistance and uniform temperature profiles.

Mechanochemical synthesis of Li₂MnO₃ shell/LiMO₂ (M = Ni, Co, Mn) core-structured nanocomposites for lithium-ion batteries.

Core/shell-like nanostructured xLi2MnO3·(1-x)LiMO2 (M = Ni, Co, Mn) composite cathode materials are successfully synthesized through a simple solid-state reaction using a mechanochemical ball-milling process. The LiMO2 core is designed to have a high-content of Ni, which increases the specific capacity. The detrimental surface effects arising from the high Ni-content are countered by the Li2MnO3 shell, which stabilizes the nanoparticles.

Effect of hydrogen plasma pretreatment on the growth of silicon nanowires and their employment as the anode material of lithium secondary batteries.

Silicon nanowires were grown from a silane and argon gas mixture directly on a stainless steel substrate by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) and used without any further treatment as the anode in the fabrication of lithium ion batteries. It was found that suitable pretreatment of the stainless steel substrate was required for the satisfactory growth of the silicon nanowires. In this study, the substrates were polished, etched in HF solution, coated with an aluminum catalyst layer with a thickness of c.

Structural and electrical characteristics of gallium tin oxide thin films prepared by electron cyclotron resonance-metal organic chemical vapor deposition.

Gallium tin oxide composite (GTO) thin films were prepared by electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD). The organometallics of tetramethlytin and trimethylgallium were used for precursors of gallium and tin, respectively. X-ray diffraction (XRD) characterization indicated that the gallium tin oxide composite thin films show the nanopolycrystalline of tetragonal rutile structure.