[en] (Ta₂O₅)_1-x(TiO₂)_x has been the most promising capacitor material to be used in the near future dynamic random access memories (DRAMs), because of its high dielectric constant, thermal and chemical stability, and good step coverage. To explore the composition dependence of dielectric properties, (Ta₂O₅)_1-x(TiO₂)_x ceramics for 0.00≤x≤0.12 with an interval of 0.01 were prepared and studied utilizing an HP4192A impedance analyzer, Raman scattering and X-ray diffraction (XRD) techniques. The dielectric properties of (Ta₂O₅)_1-x(TiO₂)_x ceramics are greatly dependent on the compositions in this range. The greatest enhancement of dielectric constant occurs when TiO₂ substitution reaches 8%. The Raman scattering and XRD studies indicate that there is some kind of phase structure appearing when a small quantity of TiO₂ is doped into Ta₂O₅. But in vicinity of x=0.08, the phase structure of these compositions is same as that of pure Ta₂O₅, which is different from the previous studies

[en] This letter describes the increase in electrical conductivity of poly(vinylidene fluoride) induced by excimer laser irradiation with λ=248 nm. The electrical conductivity was found to increase from 10^-13 to 10^-4 Ω^-1 cm^-1. As a result, experiments produced a transition in the property of the material from an insulator to a conductor. Optimal conditions for laser irradiation were determined in terms of the laser energy density, the repetition frequency, and the total number of laser shots. This letter also discusses the micromechanics of increasing conductivity in the light of Raman spectroscopy and x-ray photoelectron spectroscopy

[en] Highlights: • Photoluminescent properties from Au/ZnO/sapphire and ZnO/Au/sapphire structures have been investigated. • The enhancement of UV intensity is a result of the enhanced electric field intensity of the 325 nm excitation light. • Electron transfer which induced by the local surface may be also account for the enhancement of UV emissions. • The suppression of the visible emissions might be due to the flowing of electrons in the defect states to the Au. - Abstract: Photoluminescent properties from Au/ZnO/sapphire and ZnO/Au/sapphire structures have been investigated. It is found that due to the co-interaction between the incident light and local surface plasmons, the ultraviolet (UV) emissions from the two structures were both enhanced and the visible emissions related to the defects were suppressed. By the means of electromagnetic simulation, it indicates that the enhancement of UV intensity is a result of the enhanced electric field intensity of the 325 nm excitation light, which is induced by localized surface plasmons resonance (LSPR). On the other hand, electron transfer which is induced by the local surface also account for the enhancement of UV emissions. The suppression of the visible emissions might be due to the flowing of electrons in the defect states to the Au, which caused the reduction of the electrons in the defect states

[en] Graphical abstract: - Highlights: • Substrate effect on the near-field enhancement of microsphere-assisted laser processing was studied. • The studied substrates include silica, ITO and SiC with increased refractive index. • High refractive index of substrate results in enormous enhancement inside sphere. • The field intensity spreads deeper into the substrate with the oscillations. • The efficient near-field optical enhancement distance can be achieved about λ/2. - Abstract: Close-packed monolayer silica spheres organized through a self-assembly process have been widely used in micro/nano fabrications. In this study, we present the effects of substrate on the near-field enhancement of microsphere-assisted laser processing. There are significant differences in the surface morphology of sub-micro hole arrays on substrates with different refractive indices, which were fabricated at the same laser fluence by a KrF excimer laser (λ = 248 nm). It is found that the position of the maximum enhancement removes from the exit surface of the silica sphere into the sphere as the refractive index of substrate increased based on the simulation. In addition, the field distribution curve oscillates when there is a substrate under the microsphere, and oscillation spreads deeper into the substrate with a high refractive index. The results contribute toward the optimization of the process conditions of the microsphere-assisted laser micro/nano patterning technique and make the modification profile of the material more controllable.

[en] At room temperature, the effect of KrF pulsed excimer laser irradiation on the structural, photoluminescence, and electrical properties and on the surface morphology of ZnO thin films under different laser energy densities was investigated. Compared to the as grown sample, at an irradiation energy density of about 450 mJ/cm², the ZnO thin film exhibits a series of desirable properties: UV emission is distinctly higher, resistivity is decreased by three orders of magnitude, and the surface is flat and smooth and, at the same time, it maintains a good epitaxial orientation and a wurtzite crystal lattice structure. UV emission enhancement after laser irradiation is discussed in detail. It is suggested that the mechanism responsible for the UV enhancement is the increase in donors and not the improvement in the crystalline quality

[en] To study the physical properties of two-dimensional dodecagonal quasicrystals, the electric susceptibility, piezoelectric, elastic, photoelastic, Brillouin and Raman tensors for the point groups C₁₂, S₁₂, C_12h, C_12υ, D₁₂, D_12h are required. These tensors are tabulated here. (orig.)

[en] La_0.67Ba_0.33MnO₃ (LBMO) thin films of high quality were successfully fabricated at low temperature (400-450 deg. C) using pulsed laser deposition assisted by CO₂ laser irradiation. It is shown that, at a low deposition temperature, LBMO thin films exhibit poor crystallinity and electrical and magnetic properties. With the aid of laser irradiation, LBMO thin films are significantly improved in their structure and quality and display a resistivity maximum of 6.3 mΩ cm at 304 K, a large magnetoresistance of 20% (at 300 K, H = 2 T) and a ferromagnetic Curie temperature of ∼320 K, which are close to those of the LBMO thin films deposited at 800 deg. C. The observed improvement in the properties of the LBMO thin films deposited at low temperature is inferred to be largely associated with the enhanced crystallinity of the film and a decrease in the oxygen deficiency due to laser irradiation.

[en] The authors report significant improvement in the electrical and magnetic properties of La_0.67Ca_0.33MnO₃ thin film irradiated by CO₂ laser in air for several dozens of seconds. It is shown that after CO₂ laser irradiation the crystallinity of the film is strongly enhanced, and the surface structure is remarkably modified and displays a plainlike morphology with a lower surface roughness. The authors find that CO₂ laser irradiation results in a sharp decrease in the resistivity and a notable increase in the temperature coefficient of resistance, the insulator-metal transition temperature, and ferromagnetic transition temperature. The experimental results suggest that CO₂ laser irradiation is a fast and effective method to optimize colossal magnetoresistance materials for technological applications

[en] The tantalum-pentoxide ceramics with significantly enhanced dielectric permittivities around 60-70 (up to 71.62) at 1 MHz and 20 deg. C were prepared by CO₂ laser irradiation. The dielectric loss and the temperature coefficient of dielectric permittivity could be 0.0128 and 721 ppm/ deg. C, respectively. Dielectric properties were investigated over the temperature range from -60 to 100 deg. C at 1 MHz. The frequency dependence of the dielectric properties was also investigated between 1 kHz and 1 MHz at 20 deg. C. The stabilization of high-temperature phase at RT and crystallographic orientation in the ceramics by laser irradiation can explain the strong enhancement of the dielectric permittivity

[en] The nonlinear optic characteristics of an intense laser pulse propagating in partially stripped plasmas are investigated analytically. The phase and group velocity of the laser pulse propagation as well as the three general expressions governing the nonlinear optic behavior, based on the photon number conservation, are obtained by considering the partially stripped plasma as a nonlinear optic medium. The numerical result shows that the presence of the bound electrons in partially stripped plasma can significantly change the propagating property of the intense laser pulse.