最新刊期
卷 35 ， 期 6 ， 2014
- 摘要：Effect of embedding InAs quantum dots (QDs) on the transport properties of two-dimensional gas (2-DEG) in a modulation-doped AlGaAs/GaAs heterostructure was investigated. Samples with difference thickness (Tch) from QDs layer to 2-DEG were prepared using molecular beam epitaxy. Hall measurements show that the mobility drops dramatically with the decrease of Tch, and the electron concentration shows a same trend. Strain distributions have been measured by means of geometric phase analysis of the high-resolution transmission electron microscope images. The results show that the strain is focused in the edges and above of InAs QDs which are resulted from the extended lattice distortion. And the non-uniform strain field could be another key factor for the drop of the mobility besides coulomb scattering.关键词：quantum dots;two-dimensional electron gas;strain;molecular beam epitaxy104|110|0更新时间：2020-08-12
- 摘要：Ba1.2Ca0.64SiO4:0.10Eu,0.06Mn phosphor was synthesized at 800~1 100℃ by using MCM-41 as Si source. The influence of calcination temperature on the luminescent properties was investigated. The results indicate that the intensity and bandwidth of Eu2+ blue-green emission increase with temperature at first and then decrease. The sample calcined at 1 000℃ has the highest Eu2+ emission intensity. The peak maximum shows red-shift from 450 nm to 480 nm when the calcination temperatures changed from 800℃ and 900℃ to 1 000℃ and 1 100℃. The red emission of Mn2+ arises from the excitation by the Eu2+ emission and increases with temperature. The Eu2+ ions which can transfer energy to Mn2+ are mainly on the ten-coordinated M(1) sites.关键词：Ba1.2Ca0.64SiO4：0.10Eu;0.06Mn;MCM-41;calcination temperature;luminescence104|60|1更新时间：2020-08-12
- 摘要：The most promising application of quantum dots (QDs) is to high throughput quantitative biological information processing because of their advantages with the different emissions for single excitation wavelength. A facile method is presented to integrate Au nanoparticles with QDs for constructing QDs@Au composite nanostructures by electrostatic interaction, in which the Au nanoparticles are synthesized with sodium citrate. Based on this composite structure, the influence of the size of QDs on the FRET efficiency is researched. These results demonstrate that the QDs are effective donors in multi-homogeneous immune-assay based on FRET.关键词：quantum dots;Au nanoparticles;fluorescence resonance energy transfer;homogeneous immune-assay136|347|1更新时间：2020-08-12
- 摘要：ZnO films with diverse nanostructures, including nanorod array, nanotube array, and nanosheet array were prepared. Diameter of the nanorods and nanotubes can be tuned from 50 nm to 300 nm, and from 300 nm to 1 μm, respectively. All the ZnO nanofilms are hydrophobic. The largest contact angle 138° can be achieved without any surface modification. Moreover, the hydrophobic ZnO surface turns to hydrophilic under ultraviolet irradiation. These results provide an important basis for applying ZnO nano-arrays in the relevant aspects.108|187|2更新时间：2020-08-12
- 摘要：A novel aromatic fused heterocyclic 1,1-bis(2-benzoimididazole-yl)-2-(N-ethyl carbazole-3-yl)ethylene was synthesized by Vilsmerier-Haack reaction and Knoevenagel reaction using piperdine as catalyst with a yield of 72.53%. Elemental analysis, FT-IR, UV-Vis, 1H NMR, solution fluorescence, solid fluorescence spectroscopy, cyclic voltammetry electrochemical analysis and TG-DTA thermal analysis were used to study its structure, optical properties, electrochemical properties and thermal stability. The results show that this compound has two UV absorption peaks at 290 nm and 375 nm in the dilute solution of DMF, DMSO and DCM, and a blue-green fluorescence emission peak at 470 nm excited by 375 nm. A significant AIE effect was found through solution fluorescence tests with different V(DMSO):V(DCM) mixed solvent of this compound. Solid fluorescence spectroscopy indicate that the product has two excitation peaks at 327 and 436 nm and an emission peak at 484nm with red shift compared to the solution fluorescence. Cyclic voltammetry (CV) was employed to characterize the Eg, EHOMO, and EA of this compound, which are 2.58, 5.43, 2.85 eV, respectively. This result shows that it has good hole transporting ability and good electron transporting capability. TG/DTA analysis shows that the target product possesses good thermal stability.关键词：synthesis;Knoevenagel reaction;AIE effect;fluorescence properties128|343|1更新时间：2020-08-12
- 摘要：Sr(MoO4)x(WO4)1-x solid solution microcrystallines were synthesized by hydrothermal method. The structure, morphology, and photoluminescent properties of the microcrystallines were studied by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy (SEM), and fluorescence analysis (FA), respectively. The XRD and FT-IR results confirm that the Sr(MoO4)x(WO4)1-x microcrystallines are all typical scheelite structure with tetragonal symmetry. The SEM results show that the obtained phosphors are uniform spherical-like particles with smooth surface. Under the excitation of 275 nm ultraviolet radiation, the emission intensity in 350 nm decreases with the increasing of x, while 470 nm emission intensity increases with the increasing of x.关键词：Sr(MoO4)x(WO4)1-x solid solution;hydrothermal methods;luminescent properties89|78|2更新时间：2020-08-12
- 摘要：ZnO microstructure was prepared by solvothermal method. The morphology varied only with the proportion of deionized water and ethanol in the solvent. The morphology and size of the ZnO microstructure were observed by scanning electron microscope (SEM). The spectra of the individual particles with different morphology have been carried based on a detailed characterization by cathodoluminescence (CL) technique which could achieve nanoscale region optical properties. The spatially dependent CL results of the synthesized ZnO microstructure were obtained. It is found that the luminescence properties are related to the morphology of ZnO materials, because the morphology difference would lead to the differences on the crystal quality, interface defects, the charge distribution on the surface, and the terminated lattice face of the crystal. The luminescence properties are finally determined by these factors together.关键词：ZnO;cathodoluminescence;morphology108|127|1更新时间：2020-08-12
- 摘要：A series of MgxZn1-xO alloy films were grown on m-plane sapphire by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). Optical and structural characterizations indicated that the films with Zn mole fraction up to 55% are single-cubic-phased, and the optical bandgap of Mg0.45Zn0.55O film is 4.7 eV. The epitaxial [JP2]relationships between substrate and rocksalt MgZnO layers were determined as (110)MgznO‖(1010)sapphire,[001]MgZnO‖[1210]sapphire, and [110]MgZnO‖[0001]sapphire. The fixed uniform orientation of the films was accompanied by an improvement in crystal quality. A metal-semiconductor-metal structured solar-blind ultraviolet detector fabricated on Mg0.45Zn0.55O film showed a response peak at 260 nm and a sharp cutoff at 278 nm.关键词：cubic MgZnO;(110)-oriented;solar-blind UV photodetectors;MOCVD132|68|0更新时间：2020-08-12
- 摘要：Mg1-xZnxO thin films were deposited by pulsed laser deposition method. When growth pressure increased through inducing inert Ar during growth process, the migration energy of reactive Mg, Zn and O atoms decreased, the growth orientation of MgZnO thin film shifted from (200) to (111). The band gap value of MgZnO thin films changed with the contents of Mg and Zn atoms that combined with O atoms in MgZnO crystal lattice at different pressure, but not changed with the Mg and Zn content of the whole MgZnO thin films as reported results.关键词：ZnO;MgZnO;pulsed laser deposition;UV detector95|79|0更新时间：2020-08-12
- 摘要：Using Mg0.04Zn0.96O target, N doped MgZnO films were prepared on quartz substrate by radio frequency magnetron sputtering technique. The effects of N2/(N2+Ar) flux ratio on the morphology, structure and properties of annealed MgZnO thin films were investigated. With the increasing flux ratio of N2/(N2+Ar), the content of Mg increases, the average grain size becomes smaller, the crystal quality degrades, the resistivity increases, and the conductivity of the film changes. When the flux ratio of N2/(N2+Ar) is 20%, the MgZnO:N film behaves the best p-type conductivity property. Furthermore, the Raman peaks of the N for O site (NO) at 272 and 642 cm-1 become stronger with the flux ratio of N2/(N2+Ar) increasing. It can be concluded that the doping concentration of N for O site (NO) increases with the flux ratio of N2/(N2+Ar) increasing.关键词：radio frequency magnetron sputtering technique;N doped MgZnO films;flux ratio of N2/(N2+Ar);photoelectric properties110|98|1更新时间：2020-08-12
- 摘要：In2O3/CuO nano-heterojunction composites were prepared by sol-gel method combined electrospinning technology. X-ray diffraction and Raman spectra show that the content of CuO in the composites is increased with increasing ratios of Cu/In in the precursor solution. Absorption spectra indicate that the composite nanostructures present enhanced visible light absorption with increasing CuO content. Photocatalytic experiments show that In2O3/CuO nano-heterojunction composites have improved photocatalytic properties which could be attributed to the enhanced photogenerated charge separation of the heterojunction.关键词：In2O3;CuO;heterojunction;photocatalytic104|68|1更新时间：2020-08-12
- 摘要：Graphene-ZnO nanocomposites and pure ZnO samples were prepared by solvothermal method under the same conditions. The morphology and structure of nanocomposites were characterized by SEM, TEM, Raman and infrared spectroscopy. The results show that ZnO nanoparticles have dispersed on a few layers graphene. Compared with the morphology of graphene-ZnO nanocomposites, it is found that pure ZnO can grow into a preferred orientation of hexagonal structure, while ZnO aggregates into sphere in the presence of graphene which is attributed to the graphene hindered the preferred orientation of ZnO growth. From the PL spectra, the ultraviolet emission peak intensity of graphene-ZnO is stronger than that of pure ZnO, and accompanied by blue shift phenomenon. The difference of ultraviolet photoluminescence between ZnO and graphene-ZnO comes from the difference of morphology and the plasma effect of grapheme, while the plasma effect of graphene plays a key role.关键词：graphene;ZnO;morphology;photoluminescence101|167|0更新时间：2020-08-12
- 摘要：Carbon nanoparticles were synthesized via hydrothermal oxidation of glucose. The carbon dots were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectrophotometry, fluorescene spectrophotometry and Fourier transform infrared spectrophoto-metry (FTIR). The results indicate that the carbon dots have appropriate spherical morphology, uniform size, good dispersion, non-agglomeration. The carbon dots can emit bright green photoluminescence under UV excitation, and exhibit excitation-dependent PL behavior.关键词：hydrothermal method;photoluminescence;carbon dots453|319|15更新时间：2020-08-12
- 摘要：Low carrier mobility of organic materials limits the number of carriers extracted by electrodes. By increasing light absorption in the active layer, more excitons could be produced so as to increase current which extracted by electrodes. And the performance would be improved by this way. Photoelectric field distribution and excitons generated in P3HT:PCBM active layer were studied by the numerical modeling method. Based on it, the method of coating multilayer high reflectance films behind the cathode was proposed. Simulations reveal that the thickness of active layer plays a leading role in optical absorption. When the thickness of active layer is less than 160 nm and the thickness of Ag is less than 20 nm, coating multilayer high reflectance films could improve the optical performance of solar cells largely. Excitons increase fast with the thickness of active layer, and the number of excitons reaches an optimal value when the thickness of active layer is about 150 nm.关键词：organic film solar cells;transfer-matrix theory;multilayer high reflectance films;optical performance97|175|1更新时间：2020-08-12
- 摘要：High-efficiency red, green and blue organic light-emitting devices (OLEDs) were successfully fabricated by doping three corresponding dye into the same bipolar host material 2,7-bis(di-phenylphosphoryl)-9-[4-(N,N-dipheny-lamino]-9-phenylfluorene (POAPF). These three devices share the similar device structures which are only different in the emission layer (EML). Furthermore, a white light-emission OLED was achieved by co-doping two complementary dyes into POAPF with appropriate concentration. This white-emission device adopted a single EML structure, of which exhibit a relatively stable electroluminescent spectrum under different bias. The maximum power efficiency of these four devices is 16.50,43.72,29.78,32.83 lm/W, respectively.关键词：organic electroluminescence;phosphorescence;bipolar host;single-emissive layer109|124|4更新时间：2020-08-12
- 摘要：Al-doped ZnO conductive ceramics were fabricated in order to determine the effects of Al doping concentration on ZnO energy absorption materials. The experimental results show that Al doping concentration has great effects on the linearity, conductivity, and energy absorption density of ZnO energy absorption materials. The doping of Al2O3 can improve the linearity of ZnO conductive ceramic by reducing the barriers of ZnO grains, and the nonlinear coefficient can be as low as 1.02. When the doping mole fraction of Al is 1%, the resistivity of ZnO conductive ceramic is the lowest (0.54 Ω·cm). Al doping can improve the uniformity and density of ZnO conductive ceramic, as a result, the energy absorption density reaches to 720 J/cm3, 2~3 times higher than that of metal energy-release materials.关键词：ZnO energy absorption materials;conductivity;energy absorption density;linearity84|175|0更新时间：2020-08-12
- 摘要：GaN epitaxial films with different thickness of AlN buffer layers were grown on Si (111) by metal-organic chemical vapor deposition (MOCVD). The effects of AlN buffer thickness on in-plane stress, surface morphology and crystal quality of GaN materials were investigated. It is observed that the AlN buffer with thickness of 15 nm can effectively suppress the diffusion of Si from the substrate. Moreover, the AlN buffer can also introduce a relatively large compressive stress to GaN layers and eliminate the crack. The crack-free and mirror-like GaN layer was obtained by depositing on the AlN buffer layer with thickness of 15 nm. The full width at half maximum of the film is as low as 536 arcsec for (0002) and 594 arcsec for (1012) reflection, the in-plane tension stress is 0.3 GPa, and the RMS roughness tested by atomic force microscopy is 0.2 nm.关键词：AlN buffer layer;GaN;Si substrate;tension stress;MOCVD216|91|0更新时间：2020-08-12
- 摘要：In order to improve the electrochemical properties of lithium-ion batteries anode material ZnFe2O4, we have prepared ZnFe2O4 and a composite modified with carbon nanotubes by solvothermal reaction. The as-prepared CNT-ZnFe2O4 composite displays an excellent cycle stability with the discharge capacity of 860 mA·h·g-1 after 50 cycles. In addition, the CNT-ZnFe2O4 composite has good electrical conductivity because of the excellent electrical conductivity and thermal conductivity of the carbon nanotubes.关键词：ZnFe2O4;carbon nanotube;metal oxide;Li-ion batteries148|59|0更新时间：2020-08-12
- 摘要：In order to further clarify SPP (surface plasmon polariton) mode feature in MIM(metal-insulator-metal)waveguide, we established the theoretical pattern of SPP model relationships in which excitation and reflection coefficients are obtained. A series of results have been derived from numerical simulation. TE mode is similar to dielectric waveguide with distortion, and its propagation distance is much larger than TM0. Q value in the cavity of MIM structure increases with the length, which indicates a limited reflection of SPP. The change of quality factor in the cavity has close connection with the end face. MIM waveguide ensures better coupling of light into the desired pattern SPP in the condition of greater Q value.关键词：plasmonic;MIM waveguide;model relationships;quality factor137|388|3更新时间：2020-08-12
- 摘要：A new heatsink structure of laminated high heat conductivity pure aluminum plate was proposed for the thermal management of high power integrated LED for high mast lighting. An investigation of experiment and finite element simulation was carried out for the demonstration of the heat dissipation performance. The transient process of LED drive is longer and the steady state temperature is within the range of required operation temperature. The LED junction temperature can be effectively decreased due to the increasing of the heat dissipation area. The experiment results show that the designed heatsink and selected LED drive can satisfy the heat dissipation requirement of 250 W high power high mast lamp.关键词：high-power LED;heat sink;thermal analysis;FEM109|646|9更新时间：2020-08-12
- 摘要：Multispectral imaging is an emerging non-destructive detection technology that combines traditional two-dimensional imaging and spectroscopy techniques. In this paper, a multispectral fluorescence imaging system was developed for fast detection of pesticide residues on leaves. It took advantage of fluorescence characteristics of organophosphorus pesticide, combined with multispectral imaging technology and fluorescence excitation technique. Excited by UV-light from 190 to 300 nm, the configured organophosphorus pesticide Omethoate can emit 440 nm fluorescence, and the peak values bear a linear relationship with the concentrations of pesticide.The development of multispectral imaging system with exchangeable filters and experiment results within this article provide the technical support and theoretical basis for the construction of real-time on-line non-destructive detection system of pesticide residues.关键词：multispectral imaging;non-destructive detection;pesticide residues;fluorescence characteristics;realtime online149|465|5更新时间：2020-08-12
- 摘要：In order to investigate the energy transport process in Al film irradiated by 10 ps lasers, a semi-classical two temperature model (TTM) was applied, and a 1D finite element calculation model was constructed with finite element software. Considering phase change region of material during laser ablation, reasonable expression was added to the TTM. According to the calculation, the surface lattice temperature evolutions along with time for single pulse lasers with different powers were presented. In order to investigate the surface plasma reflectivity and the heat absorption coefficient changing with lattice temperature during laser irradiation, the free-electron gas theory was applied. Moreover, the laser generated thermoelectric field and the electron drift velocity distribution map were depicted. The results verify that the thermoelectric field is the major reason for the electron drift movement, and the location of maximum velocity is changed with time. The spatial and temporal lattice temperature distribution map of Al film irradiated by 0.12 W picosecond laser was depicted. According to the calculation, the phase explosion is the reason for ablation, and it occurs during the process of laser energy deposition. The over-heated zone (OHZ) was defined, and the relationship between ablated depths and time was found. The calculated ablation depths of single pulses coincide with the experiment for 10 ps laser.关键词：laser technique;semi-classical two temperature model;finite element method;free-electron gas theory;thermoelectric field127|238|5更新时间：2020-08-12
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China Postal code：130033
- Tel：0431-86176862 Email：fgxbt@126.com
- Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0