One-dimensional Microstructures Research Articles

Difficulties in Semiconductor Materials Analysis and Research in China

The semiconductor industry is an important support for the rapid development of the modern electronic information society, so it is important to address the depth and breadth of semiconductor research. This paper classifies and analyzes semiconductors at the chemical level, emphasizes the difficulties faced by the Chinese semiconductor market, and analyzes the semiconductor market, core tools, basic units, software design, and raw materials. Finally compared to the U.S. semiconductor market and technology, for China's status quo from the chip design and material selection point of view puts forward specific aspects can be improved, can be from zinc oxide, new silicon compounds, gallium compounds, and superlattices and one-dimensional microstructures of these four kinds of materials to make specific improvements. It is conducive to mastering the characteristics of market and industry transformation and laying a solid foundation for the development of electronic science and technology, which will help China to gain an advantageous position in the international scientific and technological competition.

Robust, biodegradable and flame-retardant nanocomposite films based on TEMPO-oxidized cellulose nanofibers and hydroxyapatite nanowires

Flammability is a fatal drawback for sustainable packaging materials made from cellulose and its derivatives. Incorporating inorganic nanomaterials is a viable approach to improve the fire-resistant property. However, due to the aggregation of inorganic fillers and weak interactions between components, incorporating inorganic nanomaterials always had an adverse impact on the mechanical properties and optical transparency of cellulose-based nanocomposites. Herein, we presented a robust, biodegradable, and flame-retardant nanocomposite film composed of TEMPO-oxidized cellulose nanofibers (TOCNFs) and inorganic hydroxyapatite nanowires (HNWs). Both TOCNFs and HNWs possessed one-dimensional microstructure and could form unique organic-inorganic networks microstructure. The organic-inorganic networks interact through physical intertwinement and multiple chemical bonds, endowing nanocomposite film with outstanding mechanical properties. This nanocomposite film showed a tensile strength of 223.68 MPa and Young's modulus of 9.18 GPa, which were superior to most reported cellulose-based nanocomposite. Furthermore, this nanocomposite film demonstrated exceptional thermal stability and flame-retardant feature attributed to the inorganic framework formed by HNWs. This nanocomposite film also possessed a high optical transmittance even when HNWs content reached 30 % and could be decomposed quickly in soil. By employing organic-inorganic interpenetrating network structure design and multiple bonding interaction, cellulose-based nanocomposites can overcome inherent limitations and attain desirable comprehensive properties.

Synergistic effect of Pd and Fe2O3 nanoparticles embedded in porous NiO nanofibers on hydrogen gas detection: Fabrication, characterization, and sensing mechanism exploration

Pd and Fe2O3 nanoparticles (NPs)-embedded porous NiO nanofibers (NFs) with high specific surface area were prepared using a facile electrospinning method. Adjusting the amount of Fe2O3 NPs in the precursor solution of electrospinning regulates the morphological evolution and crystallization of oxide heterostructures at elevated temperatures and significantly contribute to the enhanced gas sensing performance for hydrogen (H2) gas testing. Synthesized composites present the highest response of 199.24 at the optimum operating temperature of 250 °C toward 1000 ppm H2 gas, which is 65 times higher than that of only Pd-decorated NiO NFs. The response/recovery times of the sensors decreased significantly from 39/323 s for the pure sample to 11/105 s, along with good selectivity and long-term stability toward H2. The excellent gas sensing properties of the sensors is mainly attributed to the flourishing porous one-dimensional (1D) microstructure containing closely connected p-n heterojunctions of NiO and Fe2O3, which provide large specific surface areas with many active sites to promote the reaction between H2 molecules and O ion on the surface and the catalytic effect of Pd. The results demonstrate the potential of the method to fabricate gas sensors for H2 detection at ppm levels at 250 ℃ environment.

Design of crack deflection induced high toughness laminated Si3N4 ceramics based on hollow oriented one-dimensional microstructure

A laminated silicon nitride (Si3N4) ceramic material with a hollow, oriented, one-dimensional microstructure was successfully prepared based on the tape casting and sacrificial template method. The results show that hollow, oriented, one-dimensional microstructures can effectively induce crack deflection. Different arrangements of the structural design layer and dense layer will have different effects on the material. In particular, bulks with a single-layer orthogonal arrangement of the structural design layer possess high toughness and obvious crack deflection during the fracture process. A kind of multiscale crack deflection mode was realized. Compared with the fracture toughness of the monolithic Si3N4 ceramic bulk (5.55 MPa m1/2), the fracture toughness can reach 8.73 MPa m1/2, and the flexural strength can still reach 391.47 MPa with only a slight decrease.

Heterogeneous rod-like Ni@C composites toward strong and stable microwave absorption performance

Intrinsic physical property and unique nanostructures of microwave absorbing materials play an important role in their electromagnetic energy conversion. One-dimensional microstructure has been considered as an idea structure for microwave absorbers. Herein, heterogeneous rod-like Ni@Carbon (Ni@C) composites were synthesized by a handy hydrothermal reaction and a subsequent calcination treatment. Morphology analysis indicated that the resultant nanorods are composed by carbon and uniformly dispersed Ni nanoparticles (NPs). The rod-like carbon-magnetic structure could be adequately regulated via hydrothermal synthesis, resulting in tunable nano-micro structure and electromagnetic parameters. Benefiting from the magnetic–dielectric synergetic effect, the appropriate calcination temperature could improve the electromagnetic energy loss. In addition, the polarizing effect between nickel and carbon is demonstrated by density functional theory calculation. Therefore, this rod-like Ni@C composite reveals a favorable microwave absorption. The Ni@C nanorods (NC-3) possess a minimum reflection loss (RLmin) of −58.7 dB with a thickness of 1.66 mm at 13.9 GHz and achieved an effective absorption bandwidth (EAB) of 4.4 GHz. Furthermore, the carbon matrix of Ni@C acts as protective layer for Ni NPs, which could provide stable microwave absorbing performance even after one year measurement. This work introduces a facile and versatile strategy to design rod-like carbon structure as high-efficiency and stable microwave absorbers.

Enhanced electromagnetic wave absorption performance of SiCN(Fe) fibers by in-situ generated Fe3Si and CNTs

The SiCN(Fe) fibers with excellent one-dimensional microstructure and electromagnetic wave (EMW) absorption performance were synthesized by combining polymer-derived ceramics (PDCs) method and electrospinning. The in-situ generation of Fe3Si and CNTs by adding ferric acetylacetonate (FA) into the raw materials effectively improved the dielectric properties, magnetic properties and the impedance matching performance of the SiCN(Fe) fibers. The EMW absorption performance of SiCN(Fe) fibers were mainly based on dipole polarization loss, interface polarization loss and eddy current loss. The RLmin value of SiCN(Fe) fibers reached −47.64 dB at 1.38 mm and the effective absorption band (EAB, RL ≤ −10 dB) reached 4.28 GHz (13.72–18 GHz, 1.35 mm).

Available surface electronic transmission of porous SnO2/NiO hollow nanofibers for the enhanced gas-sensing performance toward n-butanol

Porous SnO2/NiO hollow nanofibers with effective surface transmission behavior have been prepared through a facile modified electrospinning method. The introduction of Ni component into the precursor solution can not only regulate the morphological evolution together with the nucleation and crystallization of oxide heterostructures at the elevated temperature action, but also significantly contribute to the enhancement of the gas-sensing performance for testing n-butanol gas. SnO2/NiO composites can present the highest response of 199 at the optimum operating temperature of 280 °C toward 100 ppm n-butanol gas, which is 4.5 times than that of pure SnO2 nanofibers. Meanwhile, the response/recovery times of the sensors can be immensely decreased from 57/16 s of pure sample to 36/10 s as the adding amount of Ni component increasing to 5%, along with the superior selectivity and long-term stability toward n-butanol. The excellent gas-sensing properties of the sensors can be mainly attributed to the flourishing porous one-dimensional (1D) microstructure containing the closely connected p-n heterojunctions of SnO2 and NiO, which can provide large specific surface areas with a mass of active sites to promote the reaction between n-butanol molecule and Oδ− on the surface.

Helical secondary structures and supramolecular tilted chirality in N-terminal aryl amino acids with diversified optical activities

Helix structures at atomic/molecular level have not been found in self-assembled peptide sequence with less than three residues. As β-sheet supramolecular secondary structures have been discovered in solid-state amino acids, we here report the conjugation of simple N-terminal aryl protecting group could give rise to helical supramolecular secondary structures in solid-state, which determines the optical activities of the adjacent aryl groups. The carboxylic acid-involved asymmetric H-bonds in N-terminal aryl amino acids induce the emergence of super-helical structures of amino acid residues and aryl groups. In most cases, supramolecular tilted chirality of aryl groups is opposite to that of amino acid sequences, of which handedness and helical pitch are determined by the H-bond modalities. Determining correlation between supramolecular tilted chirality of aryl segments and their chiroptical activities is firstly unveiled, which was verified by the computational results based on density functional theory. Most aryl amino acids self-assembled by nanoprecipitation method via crystallization induced self-assembly into rigid one-dimensional microstructures with ultra-high Young’s modulus. This study reveals the generic existence of chiral supramolecular structures in aggregated amino acid derivatives and gives an in-depth investigation into the structural-property relationships, which could guide the rational design and screening of chiroptical supramolecular materials.

Laser ablation of Ni in the presence of external magnetic field: Selection of microsized particles

The study presents results of nanosecond laser ablation of a Ni target in a liquid as a method of producing contamination-free micro- and nanosized colloidal structures. The ablation was performed in two liquids – double distilled water and ethanol, as their role on the characteristics of the ablated material is clarified. The laser ablation method in liquid was extended by applying an external magnetic field during the ablation process. A separation of micron and submicron particles from the nanoparticles in the colloidal solution is achieved by placing a substrate in the liquid, where the micron size structures are deposited under the action of the external magnetic field. At certain experimental conditions, the deposition of ordered one-dimensional microstructures on the substrate can be realized. The influence of different laser wavelengths on the features of the nanostructures dispersed in the liquid and microstructures deposited on the substrate was also investigated. On the basis of detailed analyses using Optical Microscopy, Scanning Electron Microscopy, Selected area electron diffraction, and Transmission Electron Microscopy the morphology, composition, and size distribution of the fabricated structures were studied. The presented method allows the fabrication of contamination-free micro- and nanostructures with potential applications in biotechnology, catalysis, and magneto-optics devices.

CZTS counter electrode in dye-sensitized solar cell: enhancement in photo conversion efficiency with morphology of TiO2 nanostructured thin films

In the present investigation, kesterite phase Cu2ZnSnS4 (CZTS) nanoparticle, and one-dimensional (1D) nanorods and three-dimensional (3D) flower-like rutile phase TiO2 thin films were obtained by the conventional hydrothermal method. The (112) plane–oriented single-phase CZTS nanoparticles with chemical composition Cu/(Zn + Sn) = 0.84, 0.90, 1.05 were obtained by changing the copper concentration of the precursor solution. The CZTS thin films were prepared on fluorine-doped tin oxide (FTO) substrate by the doctor blade coating method. The effect of reaction time on growth of the hydrothermal deposited rutile phase TiO2 nanorod thin films were investigated. The detailed structural properties, phase identification, and morphological developments were investigated using X-ray diffraction (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM) techniques. The dye-sensitized solar cells were fabricated with CZTS counter electrodes (CEs) and hydrothermal deposited nanostructured TiO2 photoanodes. The device formed with three-dimensional TiO2 nanostructured photoanode showed higher efficiency (2.65%) than one-dimensional microstructures (1.74%). The study demonstrates that the nanostructure-based morphologies of TiO2 photoanodes affect the performance of CZTS CEs–based dye-sensitized solar cell.

Pea-like Fe/Fe3C Nanoparticles Embedded in Nitrogen-Doped Carbon Nanotubes with Tunable Dielectric/Magnetic Loss and Efficient Electromagnetic Absorption.

One-dimensional microstructure has been regarded as one of the most desirable configurations for magnetic carbon-based microwave absorbing materials (MAMs). Herein, pea-like Fe/Fe3C nanoparticles embedded in nitrogen-doped carbon nanotubes (Fe/Fe3C@NCNTs) are successfully prepared through a direct pyrolysis of the mixture of FeCl3·6H2O and melamine under inert atmosphere. The chemical composition and microstructural feature of these Fe/Fe3C@NCNTs composites are highly dependent on the pyrolysis temperature. As a result, their electromagnetic properties can be also manipulated, where dielectric loss gradually decreases with the increasing pyrolysis temperature and magnetic loss presents a reverse variation trend. When the pyrolysis temperature reaches 600 °C, the as-obtained composite, Fe/Fe3C@NCNTs-600 can perform a maximum reflection loss of -46.0 dB at 3.6 GHz with a thickness of 4.97 mm and a qualified bandwidth of 14.8 GHz with the integrated thickness from 1.00 to 5.00 mm. It is very interesting that the microwave absorption performance of this new kind of composites is not so susceptible to the pyrolysis temperature as those common magnetic carbon-based MAMs because there is an effective balance between dielectric loss and magnetic loss, which accounts for a very stable attenuation ability when the pyrolysis temperature range changes from 600 to 700 °C. These favorable characteristics, including low-cost raw materials, easy preparation, and stable performance, may render Fe/Fe3C@NCNTs composites as a novel kind of MAMs in the future.

Ultrabroadband Near-perfect Anisotropic Metamaterial Absorber Based on a Curved Periodic W/TPX Stack

ABSTRACTA one-dimensional periodic microstructure was presented for an ultrabroadband near-perfect absorber for thermal radiation. The microstructure comprised a curved periodic stack of tungsten (15 nm) and polymethylpentene (TPX) (35 nm) with 20 layers deposited on a half-cylindrical cavity fabricated on a tungsten substrate. Visible to midinfrared regions (200 nm to 10.9 μm) allow an average measured light absorptivity of approximately 90% for transverse magnetic polarized waves at normal incidence; this property is insensitive to polar angle even when the incident angle is 80°. These superior performances were primarily attributed to intrinsic bandgap absorption in tungsten, excitation of SPPs at the air/W interface, and the resonance of the slow-light effect and its higher-order modes. Furthermore, the spectrum range of near-perfect absorption could be tuned by adjusting the center half-cylindrical shell radius, total pair number and dielectric permittivity. Moreover, the imperfection tolerance of the proposed system was studied by varying the filling ratio of metal in a periodic shell. This work may provide new guidelines for designing metamaterials absorbers that can obtain highly enhanced absorption over an ultrabroadband and in a wide range of angle of incidence.

Femtosecond Laser Writing of Waveguide Microstructures in Pb(Zr,Ti)O3 Films and Their Characterization by the Nonlinear Optical Method

Femtosecond laser writing of ferroelectric one-dimensional microstructures possessing waveguide and nonlinear optical properties in Pb(Zr,Ti)O3 films is considered, and the passage of light beams via obtained waveguide structures is traced. The optimum speed and power density of the writing laser beam are within 50–500 μm/s and 1–1.5 MW/cm2, respectively. A two-stage method of writing is proposed, which provides for improved nonlinear optical properties of obtained waveguide microstructures.

Фемтосекундная лазерная запись волноводных микроструктур в пленках Рb(Zr,Ti)О-=SUB=-3-=/SUB=- и их характеризация нелинейно-оптическим методом

AbstractFemtosecond laser writing of ferroelectric one-dimensional microstructures possessing waveguide and nonlinear optical properties in Pb(Zr,Ti)O_3 films is considered, and the passage of light beams via obtained waveguide structures is traced. The optimum speed and power density of the writing laser beam are within 50–500 μm/s and 1–1.5 MW/cm^2, respectively. A two-stage method of writing is proposed, which provides for improved nonlinear optical properties of obtained waveguide microstructures.

Boosted electrochemistry properties of Cu4[(OH)0.29Cl0.71](OH)6 hexagonal prisms by 3D-cage atomic configuration of (100) facet

Abstract The Cu 4 [(OH) 0.29 Cl 0.71 ](OH) 6 hexagonal prisms, nanoplates and nanosheets are prepared by a simple hydrothermal method, and we have mainly investigated their electrochemistry properties. At 31.25, 62.5, 125, 250 and 500 mAg −1 , the discharge capacitances of hexagonal prisms (S0) electrode are 1186, 1023, 969, 934 and 918 mFg −1 , respectively; whereas 547, 508, 469, 438 and 375 mFg −1 for hexagonal nanosheets (S10), respectively. The capacitance of 3–8 μm-long hexagonal prisms (0.25 m 2 g −1 ) is 2 times higher than that of 50–100 nm-thick hexagonal nanosheets (3.54 m 2 g −1 ), which is obviously beyond our imagination. The high capacitance of the former sample has been mainly attributed to the atom configuration of {100} facets and the high electrical conductivity. Compared with the hexagonal tunnel atom configuration of {001} facets, the three-dimensional (3D) cage atom configuration in {100} facets favors for the charge storage, thus leading to a higher capacitance of hexagonal prisms, which has rarely been reported yet. Further, the hexagonal prisms have a higher electrical conductivity than nanoplates and nanosheets, suggesting that the one-dimensional (1D) microstructure is beneficial to the electron transfer. This work enlightens us that the electrochemistry properties of materials can be improved by the exposed facets with unique atom configuration.

Facile method to align crystalline needles composed of organic semiconducting materials using a balance between centrifugal and capillary forces

Methods to align one-dimensional microstructures composed of organic materials have attracted much attention because of their potential applications to devices such as field-effect transistors. Although dip coating is one of the methods (using self-assembly) used for the purpose, its disadvantage is that a larger amount of the material dissolves in the solution than what actually gets deposited on substrate. In this study, we developed a novel method that requires a small amount of precursor solution. By placing a polydimethylsiloxane block on a glass substrate and rotating the substrate using a spin coater, a small amount of the precursor solution was confined in a narrow region along the foot of the block. When we used an organic semiconducting material, 9,10-dibromoanthracene, as a solute, aligned and roughly oriented crystalline needles were precipitated. The thicknesses and lengths of the crystalline needles were controlled by the composition of the solvent and the rotation speed.

Ca-Doped Strontianite–Calcite Hybrid Micropillar Arrays Formed via Oriented Dissolution and Heteroepitaxial Growth on Calcite

Even though heteroepitaxial growth of one-dimensional microstructures or three-dimensional islands has been realized via strategies such as chemical vapor deposition, molecular beam epitaxy, and solution phase, researchers have not succeeded in the formation of one-dimensional hybrid microstructures via the combination of heteroepitaxial growth and oriented dissolution up to now. In this work, well ordered single crystalline calcium-doped strontianite–calcite hybrid micropillar arrays with the long axis along the [001] direction of the two phases were formed on calcite (104) substrates via heteroepitaxial growth of strontianite and oriented dissolution of calcite in aqueous solution for the first time. Energy-dispersive spectroscopy analysis shows that the micropillars are composed of strontianite occluded with about 12 mol % of Ca. During the growth process of strontianite, calcite cores formed in the inner side of the strontianite micropillars at the base stage via the oriented dissolution. The lattices of the strontianite and calcite match very well at the interface of calcite and strontianite. A novel formation mechanism is proposed for the formation of Ca-doped strontianite–calcite hybrid micropillars via the synergetic process of the oriented dissolution of one carbonate mineral and the heteroepitaxial growth of another carbonate mineral in Volmer–Weber growth mode with a small lattice misfit. Ca-doped strontianite micropillar arrays might grow epitaxially on the calcite (001) and (104) planes with small misfits.

Characterization of thermal transport in one-dimensional microstructures using Johnson noise electro-thermal technique

This work reports on the development of a Johnson noise electro-thermal (JET) technique to directly characterize the thermal conductivity of one-dimensional micro-/nanoscale materials. In this technique, the to-be-measured micro-/nanoscale sample is connected between two electrodes and is subjected to steady-state Joule heating. The average temperature rise of the sample is evaluated by simultaneously measuring the Johnson noise over it and its electrical resistance. The system’s Johnson noise measurement accuracy is evaluated by measuring the Boltzmann constant (k B). Our measured k B value (1.375 × 10−23 J/K) agrees very well with the reference value of 1.381 × 10−23 J/K. The temperature measurement accuracy based on Johnson noise is studied against the resistance temperature detector method, and sound agreement (4 %) is obtained. The thermal conductivity of a glass fiber with a diameter of 8.82 μm is measured using the JET technique. The measured value 1.20 W/m K agrees well with the result using a standard technique in our laboratory. The JET technique provides a very compelling way to characterize the thermophysical properties of micro-/nanoscale materials without calibrating the sample’s resistance–temperature coefficient, thereby eliminating the effect of resistance drift/change during measurement and calibration. Since JET technique does not require resistance–temperature correlation, it is also applicable to semi-conductive materials which usually have a nonlinear I–V relation.

Formation kinetics and photoelectrochemical properties of crystalline C70 one-dimensional microstructures

We discovered that solvents play a critical role in determining the morphology, formation process and intrinsic properties of several C70 one-dimensional microstructures, which show superior photoelectrochemical properties.

One-dimensional Microstructure Tungsten Gratings for Thermo Photovoltaic Applications

In this study, a one-dimensional microstructure tungsten grating is optimized for potential application as Thermo Photovoltaic (TPV) emitter. The influence of gratings geometric parameters on the spectral emittance are studied by using the Rigorous Coupled-Wave Analysis (RCWA). The results show that the spectral emittance is affected by the gratings geometrical parameters and insensitive to the direction. The optimum parameters of the proposed structure are grating period 1.4 µm, a filling ratio 0.8 and grating height 0.2 µm. A broad peak of high emittance is obtained at wavelengths between 0.5 and 1.8 μm. A peak emittance close to unity at wavelengths between 0.5 and 2 µm is achieved and it drops below 0.2 at wavelengths above 2 µm. This can be explained by the surface plasmon polaritons excitation coupled with the grating microstructures. At longer wavelengths, the emittance remains low and this is highly desired for thermo photovoltaic applications to reduce the thermal leakage due to low-energy photons that do not produce any photocurrent. The proposed structure can be used as a selective emitter for TPV applications.