Design of a solid-state nanopore-based platform for single-molecule spectroscopy

We numerically assess the light propagation and distribution characteristics of electromagnetic fields on nanopores formed in dielectric and metal/dielectric membranes using a frequency-domain finite element method (3D full-wave electromagnetic field simulation). Results of such studies were used to identify aluminum as an ideal material for use in optically thick metal/dielectric membranes. The comparison between SiN and Al/SiN membranes (with and without a submicron sized aperture) was numerically and experimentally shown to verify the effect of optically thick metal layers on light propagation and fluorescence excitation. The cut-off behavior for Al/SiN membranes with varying pore diameters was investigated in terms of light propagation, distribution of electromagnetic fields, and light attenuation characteristics.     

Giant white and blue light emission from Al(2)O(3) and ZnO nanocomposites

A new and general approach enabling us to amplify not only the bandgap emission of ZnO nanorods but also the defect emission of Al(2)O(3) is proposed. The light intensity of the band edge emission of ZnO nanorods can be improved by as much as 19 times after the decoration of Al(2)O(3) layers. Moreover, white light emission arising from Al(2)O(3) defects in ZnO/Al(2)O(3) nanostructures also shows a large enhancement factor of 12 times. Our new strategy offers an alternative possibility to create strong white and blue light-emitting devices.     

Refraction and diffraction by a metal-dielectric multilayered structure

An optical refraction prism consisting of metal and dielectric, subwavelength, periodic multilayered thin films has been proposed. The multilayered structure of metal and dielectric thin films has a cylindrical dispersion surface for TM polarized light. The light behaviors are very different from those of conventional glass prisms and photonic crystal superprisms. Refraction and diffraction of the light wave for the metal-dielectric multilayered prism has been investigated by numerical simulations and graphical representation based on the dispersion surface. A prism with 0.2 microm period had an angular dispersion of 0.20 degrees /nm for approximately 0.8 microm wavelength light. The finite thick metal-dielectric multilayered structure acted as a slab waveguide.     

Unraveling the Raman Enhancement Mechanism on 1T′‐Phase ReS2 Nanosheets

2D transition metal dichalcogenides materials are explored as potential surface‐enhanced Raman spectroscopy substrates. Herein, a systematic study of the Raman enhancement mechanism on distorted 1T (1T′) rhenium disulfide (ReS₂) nanosheets is demonstrated. Combined Raman and photoluminescence studies with the introduction of an Al₂O₃ dielectric layer unambiguously reveal that Raman enhancement on ReS₂ materials is from a charge transfer process rather than from an energy transfer process, and Raman enhancement is inversely proportional while the photoluminescence quenching effect is proportional to the layer number (thickness) of ReS₂ nanosheets. On monolayer ReS₂ film, a strong resonance‐enhanced Raman scattering effect dependent on the laser excitation energy is detected, and a detection limit as low as 10^?9m can be reached from the studied dye molecules such as rhodamine 6G and methylene blue. Such a high enhancement factor achieved through enhanced charge interaction between target molecule and substrate suggests that with careful consideration of the layer‐number‐dependent feature and excitation‐energy‐related resonance effect, ReS₂ is a promising Raman enhancement platform for sensing applications.     

Role of metal and dielectric nanoparticles in the performance enhancement of silicon solar cells

The suitability of using spherical metal and dielectric nanoparticles on the top of a silicon solar cell has been investigated. An enhancement index factor (EIF) for each wavelength of light and an averaged EIF for the AM 1.5 solar spectrum, weighted by the photon flux, has been introduced. These factors estimate the effect of the nanoparticles in improving the performance of the solar cells, considering the absorption loss due to joule heating, fraction of radiation scattered into the substrate and the front scattered radiation pattern. A systematic comparison between silver and dielectric nanoparticles (silica, silicon nitride, titanium dioxide) shows that titanium dioxide and silicon nitride nano particles of sizes ≥100?nm exhibit larger enhancements compared to that of silver nanoparticles of similar sizes. Further, as the dielectric constant of the dielectric nanoparticles increases, the optimal particle size corresponding to maximal enhancement shifts towards lower value. At optimal particle sizes, the enhancement is 1.5–2 times greater than that due to silver nanoparticles.     

Film-loaded SAW waveguides for integrated acousto-optical polarization converters

We report on a detailed theoretical and experimental investigation of film-loaded surface acoustic wave (SAW) waveguides in lithium niobate (LiNbO3) for integrated acousto-optical (AO) polarization converters. The numerical analysis is based on both a scalar and a full-vectorial model. Dispersion plots and figures of merit for several structures are given, which lead to design parameters for optimized polarization converters. It is pointed out that very attractive structures are metal/dielectric/LiNbO3 strip waveguides and dielectric/LiNbO3 slot waveguides, in which metal is either gold (Au) or aluminum (Al), and the dielectric film is an optical transparent material such as silicon oxide (SiO2), magnesium oxide (MgO), or aluminium oxide (Al2O3). Polarization converters with the designed acoustical waveguides have been realized and characterized by optical conversion and laser probing measurements.     

Propagation of longitudinal leaky surface waves under periodic SiO (2)/Al structure on Li(2)B(4)O(7) substrate

The properties of longitudinal leaky surface waves (LLSW) under a periodic SiO(2)/Al structure on Li(2)B(4)O (7) (LBO) substrate, were investigated theoretically and experimentally, in order to improve the high propagation losses of LLSWs under a periodic Al grating with the normalized thickness over 2%. In the theoretical analysis, the previously presented method based on the boundary integral equations for the periodic metal grating structure on the substrate was extended to include the dielectric layer. In the experiments, devices with Al electrodes recessed into a SiO(2) groove on LBO were fabricated, and the propagation losses of them were estimated. As a result, it was shown that, when the surface of the structure was flattened, the propagation losses were sufficiently low and the first Bragg stopband width decreased.     

High performance flexible organic thin film transistors (OTFTs) with octadecyltrichlorsilane/ Al2O3/poly(4-vinylphenol) multilayer insulators

The incorporation of a thin, atomic layer deposited Al2O3 layer in between a spin-coated poly-4-vinyl phenol (PVP) organic layer and octadecyltrichlorsilane (OTS) in the multilayer gate dielectric for pentacene organic thin film transistors on a n(+)-Si substrate reduced the gate leakage current and thereby significantly enhanced the current on/off ratio up to 2.8 x 10(6). Addition of the OTS monolayer on the UV-treated Al2O3 improved the crystallinity of the pentacene layer, where the OTS/UV-treated Al2O3 surfaces increased their contact angles to 100 degrees. X-ray diffraction (XRD) analysis revealed a more intense (001) crystal reflectance of pentacene deposited on OTS/UV-treated Al2O3 surface than that on OTS/Al2O3 surface. Moreover, the improved pentacene layer contributed to the field effect mobility (0.4 cm2/Vs) and subsequently improved the electrical performances of organic thin film transistor (OTFT) devices. This PVP/UV treated Al2O3/OTS multilayer gate dielectric stack was superior to those of the device with the single PVP gate dielectrics due to the improved crystallinity of pentacene.     

低温共烧氧化铝/玻璃复合基板材料的研究

以低软化点的钙硼硅酸盐玻璃和氧化铝粉末为原料,制备了氧化铝/玻璃低温共烧复合基板材料。所需的玻璃粉体采用溶胶-凝胶法制备。研究了烧结温度和氧化铝含量对复合材料的烧结特性、介电性能以及力学性能的影响。结果表明,当氧化铝质量分数为50%,复合材料经950℃、保温2 h烧结后,其εr=5.92,tanδ=5.7×10-4,ρ=1012Ω.cm,抗弯强度σ=167.82 MPa,热膨胀系数α=4.86×10-6/℃,可望作为低温共烧多层陶瓷基板材料应用。     

Ti/Al_2O_3界面的光电子能谱研究

用X射线光电子谱（XPS）和俄歇电子能谱（AES）研究了Ti／Al_2O_3界面形成的过程。研究表明，活性金属Ti在室温下能与衬底Al2O3（1102）形成约20nm强结合的界面区。从Al，O，Ti的光电子谱形状变化以及它们随着Ti覆盖度的增加而出现结合能位移表明，在界面处形成的反应层中，最初几个单层的Ti很容易被Al2O3表面的活性氧所氧化，从而使Ti／Al2O3界面逐步由具有更强相互作用的TiOx／Al2O3界面所代替，并形成由多相混合体［Ti-O相，（Ti，Al）2O3相以及金属Al相］所组成的界面区。就是说，Ti通过Al—O键的O2-离子转移其电子给Al3 并使它还原成金属Al，从而形成Ti－O键所致。本文用AES强度剖面分析观察到了这种被还原的Al。     

Mn、Fe和Cu氧化物在低温等离子体催化氧化甲苯体系中的活性比较

采用等体积浸渍法制备了MnOx/γ-Al2O3、FeOx/γ-Al2O3和CuOx/γ-Al2O3催化剂,测定了不同催化剂在低温等离子体场内分解甲苯的活性,用X射线衍射(XRD)、氢气程序升温还原(H2-TPR)技术对催化剂进行表征。结果表明催化剂分解甲苯的活性的顺序是MnOx/γ-Al2O3>FeOx/γ-Al2O3>CuOx/γ-Al2O3。催化剂分解臭氧的实验表明,不同催化活性组分对臭氧的催化分解性能顺序与对甲苯的分解性能顺序是一致的。MnOx/γ-Al2O3催化剂的Mn负载量对其催化活性有明显影响,Mn的含量为1%(质量分数)时,催化剂的活性最高,当能量密度为19J/L时,其对甲苯催化氧化的转化率接近100%。催化剂表征结果表明当Mn含量为1%(质量分数)时,氧化锰在载体γ-Al2O3上最接近单层分散量,此时活性组分与载体表面的相互结合力最强,在载体上有很好的分散性,从而表现出对甲苯分解的最好性能。     

Morphotropic phase boundary (MPB) effect in Pb (Zr,Ti)O3 rhombohedral/tetragonal multilayered films

Alternating rhombohedral/tetragonal Pb(Zr_xTi_1−x)O₃ (P_x) multilayered films were prepared via a chemical solution method. It has been found that the P45/P55 multilayers show significant dielectric enhancement comparing with the uniform P45 and P55 films, and this dielectric enhancement increases as the decrease of the layer periodicity. However, the dielectric constant of the Pb(Zr,Ti)O₃ rhombohedral/tetragonal multilayered films decreases when the layer compositions are away from morphotropic phase boundary (MPB), and no remnant polarization enhancement was observed in all the multilayered films. After comparing the dielectric and ferroelectric properties of the multilayers with the corresponding single-phase films, the dielectric enhancement in P45/P55 multilayers was ascribed to the formation of the MPB region around the interfaces between the P45 and P55 layers.     

High-performance low-voltage organic field-effect transistors prepared on electro-polished aluminum wires

We report the preparation of high-performance low-voltage pentacene-based organic field-effect transistors (OFETs) fabricated on a metallic fiber (Al wire) substrate. The surface roughness of the wire was significantly reduced after 10 min of electro-polishing. A 120 nm thick Al(2)O(3) gate dielectric layer was deposited on the anodized wire, followed by octadecyltrichlorosilane (ODTS) treatment. The ODTS-modified Al(2)O(3) gate dielectrics formed around the Al wire showed a high capacitance of 50.1 nF cm(-2) and hydrophobic surface characteristics. The resulting OFETs exhibited hysteresis-free operation with a high mobility of 0.345 cm(2) V(-1) s(-1) within a low operating voltage range of -5 V, and maintained their high performance at an applied tensile strain of bending radius ~2.2.     

金属/绝缘体/金属(Al/Al2O3/Au)隧道结的发光衰减机制

结合Al/Al2 O3 /Au结构MIM(metal/insulator/metal)隧道结I U特性、深度Auger谱及结发光后结面透明度的测试与观察 ,对其发光衰减机制进行了研究。结果表明 ,由于MIM结工作时 ,通过隧道电流等产生的大量焦耳热引起底电极Al膜不断氧化 ,中间栅Al2 O3 的厚度不断增加 ,从而使得隧穿电子激发表面等离极化激元 (surfaceplasmonpolariton ,SPP)的强度不断变弱 ,引起SPP耦合发光的强度不断衰减     

MIM-MIS隧道结的发光光谱特性

对MIM(Au-SiO2-Al)和MIS(Au-SiO2-Si)隧道结的表面等离极化激元(surfaceplasmonpolariton,SPP)的激发与色散关系进行了讨论,对结的发光光谱进行了测试。结果表明其发射峰主峰位于610nm(2.00eV)～630mm(2.00eV)和700mm(1.77eV)～740nm(1.68eV)处,分别与Au/空气及Au/Al2O3(SiO2)界面SPP模式的激发相对应。结的发光过程应该是隧穿电子激发表面等离极化激元SPP,然后SPP与粗糙度耦合形成光发射。     

Microstructure of Co-Ni-Al2O3 Composite Coatings by Electroforming

The metal matrix composite coatings of Co-Ni-Al2O3 were studied by electrolytic codeposition of Co-Ni alloys and Al2O3 on a Cu substrate from a sulfamate electrolyte containing Al2O3 particles. It was illustrated from the examined results of SEM, AFM and     

Spatially resolved stress analysis in Al2O3/3Y-TZP multilayered composite using confocal fluorescence spectroscopy

Fluorescence piezo-spectroscopy (PS) was applied to evaluate the residual stress fields stored in a multilayered Al(2)O(3)/3Y-TZP (3 mol% Y(2)O(3)-stabilized ZrO(2)) composite using the chromophoric fluorescence spectra of Al(2)O(3). The PS results were compared with a theoretical stress distribution in the laminate, calculated according to a repeating unit cell model. However, in practical fluorescence spectroscopy, each measurement point corresponded to a finite volume of material, within which the scattered light experienced fluorescence wavelengths characteristic of the local (weight-average) stress fields. Because of the finite volume of material probed in PS measurements, a comparison between the experimental and calculated values requires that the calculated stresses be convoluted according to the depth-response function of the probe. A pinhole aperture incorporated in the Raman microprobe was used to control the collection probe depth and to modulate the portion of the whole fluorescence emission reaching the detector. According to calibrations of the probe depth and probe response function, probe-convoluted stresses were obtained and a spatially resolved mapping of residual stresses could be obtained.     

Effects of Al2O3—Particulate—Contained Composite Filler Materials on the Shear Strength of Slumina Joints

Al2O3/Al2O3 joints were brazed with a new kind of filler materials,which were formed by adding Al2O3 particulates into Ag-Cu-Ti active filler metal.The results showed that the material parameters (the Ti content,Al2O3 particulate volume fraction) of the composite filler materials affected the shear strength of brazed joints.When the Ti content was 2 wt pct in the filler metal, the shear strength of brazing joints decreased with the increasing the volume ratio of Al2O3 particulate .When the Ti content was 3 wt pct in the filler metal, the shear strength of joints increased from 93.75 MPa(Al2O3 pOvol pct) to 135.32 MPa(Al2O3 p15 vol.pct).     

Investigation of alumina-silica films deposited by pulsed injection metal-organic chemical vapour deposition

This work is devoted to deposition of alumina-silica films using an innovative pulsed injection metal organic chemical vapour deposition technique and aluminium tri(iso-propoxide) (Al(i-OPr)₃) and tetraethoxysilane (TEOS) as precursors. The deposited aluminium silicate films have been characterised by scanning electron microscopy, infrared spectroscopy, X-ray diffractometry and capacitance-voltage (C-V) measurements. The investigation of the deposition at different Si/Al ratios and substrate temperatures has shown that the growth rate increases with the increase of Al(i-OPr)₃ proportion in solution and decreases as the proportion of TEOS increases. We have also shown that aluminium content in the film increases at lower deposition temperatures while silicon content increases at higher temperatures. The permittivity of the films determined from C-V measurements decreases with increasing substrate temperature. It was found that films deposited at substrate temperatures of 600 or 700 °C and with the highest Si/Al ratio have the lowest dielectric permittivity. This research should be useful for further development of MOCVD technology for the deposition of aluminosilicate-based dielectric materials with controlled dielectric permittivity.     

Room temperature observation of size dependent single electron tunneling in a sub-2 nm size tunable Pt nanoparticle embedded metal-oxide-semiconductor structure

In this paper we report size dependent single electron tunneling behavior at room temperature in a metal-oxide-semiconductor structure with uniformly sized Pt nanoparticles embedded in an Al(2)O(3) dielectric. The sub-2 nm size Pt nanoparticles sandwiched between the Al(2)O(3) layers are deposited by a unique tilted target sputter deposition technique which produces metal nanoparticles as small as 0.5 nm with narrow size distributions at room temperature. The charging behavior of these nanoparticles shows clear single electron tunneling peaks due to the Coulomb blockade effect. Moreover, the average single electron addition energy and height of the single electron tunneling current strongly depend on the size of the Pt nanoparticle. These controllable single electron tunneling behaviors suggest a new route for fabrication of single electron devices.