In the last 30 days

• Open/close Development and Characterization of Metal-Insulator-Metal Capacitors with SiN_x Thin Films by Plasma-Enhanced Chemical Vapor Deposition

  Wang Cong et al 2010 Chinese Phys. Lett. 27 078101 Tag this article

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  We report the fabrication of high breakdown voltage metal-insulator-metal (MIM) capacitors with 200-nm silicon nitride deposited by plasma-enhanced chemical vapor deposition with 0.957 SiH ₄/NH ₃ gas mixing rate, 0.9 Torr working pressure, and 60 W rf power at 250° C chamber temperature. Some optimized mechanisms such as metal source wiping, pre-melting and evaporation rate adjustment are used for increasing the yield of the MIM capacitors. N ₂ annealing and O ₂/H ₂ plasma pre-deposition treatment is proposed to increase the reliability of the MIM capacitors in high-temperature, high-pressure, and high-humidity environments. A 97% yield and up to 148 V breakdown voltage of a 13.06 pF MIM capacitor with 0.04 mm ² die area can be fabricated.

• Open/close Chaotic Dynamics in a Sine Square Map: High-Dimensional Case (N ≥ 3)

  Xu Jie et al 2010 Chinese Phys. Lett. 27 080506 Tag this article

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  We study an N-dimensional system based on a sine square map and analyze the system behaviors of cases of dimension N ≥ 3 with the tools of nonlinear dynamics. In the three-dimensional case, bifurcations in the parameter plane, invariant manifolds, critical manifolds and chaotic attractors are studied. Then we extend this study to the cases of higher dimension (N > 3) to understand generalized properties of the system. The analysis and experimental results of the system demonstrate the existence of bounded chaotic orbits, which can be considered for secure transmissions.

• Open/close Ground State Energy of One-Dimensional δ-Function Interacting Bose and Fermi Gas

  You Yi-Zhuang 2010 Chinese Phys. Lett. 27 080305 Tag this article

  Article References Full text PDF (333 KB)

  The ground state energy curves of one-dimensional δ-function interacting bose and fermi gas are fitted with simple algebraic approximations according to their asymptotic behaviors.

• Open/close Effect of Microstructure of TiO₂ Thin Films on Optical Band Gap Energy

  Tian Guang-Lei et al 2005 Chinese Phys. Lett. 22 1787 Tag this article

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  TiO ₂ coatings are prepared on fused silica with conventional electron beam evaporation deposition. After annealed at different temperatures for four hours, the spectra and XRD patterns of TiO ₂ thin film are obtained. XRD patterns reveal that only anatase phase can be observed in TiO ₂ coatings regardless of the different annealing temperatures, and with the increasing annealing temperature, the grain size gradually increases. The relationship between the energy gap and microstructure of anatase is determined and discussed. The quantum confinement effect is observed that with the increasing grain size of TiO ₂ thin film, the band gap energy shifts from 3.4 eV to 3.21 eV. Moreover, other possible influence of the TiO ₂ thin-film microstructure, such as surface roughness and thin film absorption, on band gap energy is also expected.

• Open/close Waveguide Bend of 90° in Two-Dimensional Triangular Lattice Silicon Photonic Crystal Slabs

  Zhou Chang-Zhu et al 2010 Chinese Phys. Lett. 27 084203 Tag this article

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  We design and realize a 90° waveguide bend in two-dimensional triangular lattice silicon photonic crystal slabs by connecting linear waveguides along the orthogonal Γ – K and Γ – M directions. A pass band of 70 nm is realized by optimizing the geometry of the Γ – M waveguide. The connection region of the waveguide bend is optimized to improve the transmission efficiency of infrared light through the two different kinds of waveguides. The transmission efficiency of an optimized single bend is about 75% in simulation and 45% in measurement.

• Open/close On the Generalized Continuity Equation

  Arbab I. Arbab and Hisham. M. Widatallah 2010 Chinese Phys. Lett. 27 084703 Tag this article

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  A generalized continuity equation extending the ordinary continuity equation is found using quanternions to show it is compatible with Dirac, Schrödinger, Klein–Gordon and diffusion equations. This generalized equation is Lorentz invariant. The transport properties of electrons are found to be governed by the Schrödinger-like equation and not by the diffusion equation.

• Open/close Thermoelectric Performances of Free-Standing Polythiophene and Poly(3-Methylthiophene) Nanofilms

  Lu Bao-Yang et al 2010 Chinese Phys. Lett. 27 057201 Tag this article

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  Thermoelectric performances of free-standing polythiophene (PT) and poly(3-methylthiophene) (PMeT) nanofilms with high tensile strength electrosynthesized from boron trifluoride diethyl etherate (BFEE) are systematically investigated. They display decent electric conductivity (47 and 73 S · cm ⁻¹), high Seebeck coefficient (130 and 76 μ V · K ⁻¹) and low thermal conductivity (0.17 and 0.15 W · m ⁻¹ · K ⁻¹) at room temperature. Their figure of merit can reach 3.0 × 10 ⁻² at 250K, higher than that of many other conducting polymers. The decrease of charge carrier concentration resulting from volatile and water-sensitive dopants from BFEE leads to the decrease of electrical conductivity but a substantial increase of the Seebeck coefficient, making their figure-of-merit values maintained at more than 10 ⁻² even after prolonged storage (two months). Moreover, free-standing PT and PMeT exhibit much better thermoelectric performances than those in pressed pellets due to the good arrangement of the polymer chains and preferably oriented structure in films. It therefore provides a way to improve the thermoelectric performances of conducting polymers by controlling regularity of the extended conjugated chain structure and/or the chain packing to achieve high charge mobility.

• Open/close Spin ½ Fermions in 1D Harmonic Trap with Repulsive Delta Function Interparticle Interaction

  Ma Zhong-Qi and C. N. Yang 2010 Chinese Phys. Lett. 27 080501 Tag this article

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  Following the general theory developed in our earlier papers I [ Chin. Phys. Lett. 26 (2009) 120506] and II [ Chin. Phys. Lett. 27 (2010) 020506] for Bosons, we extend the investigation to trapped spin ½ Fermions.

• Open/close Laser-Driven Silver Nanowire Formation: Effect of Femtosecond Laser Pulse Polarization

  Bian Fei et al 2010 Chinese Phys. Lett. 27 088101 Tag this article

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  We report our laser-driven method used to make large quantities of straight thin silver nanowires, and experimentally demonstrate that femtosecond laser pulse polarization has a prominent effect on formation of non-spherical shapes of nanoscale particles. Further, our experiment directly reveals that the underlying mechanism is plasmon-plasmon interaction, which can be controlled by polarization and plays a decisive role in this non-synthetic method for metal nanowire formation.

• Open/close Kondo Effect in Self-Assembled Manganese Phthalocyanine Monolayer on Pb Islands

  Ji Shuai-Hua et al 2010 Chinese Phys. Lett. 27 087202 Tag this article

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  The Kondo effect in two-dimensional manganese phthalocyanine (MnPc) self-assembled monolayer films on Pb(111) islands is studied by low-temperature scanning tunneling microscopy. Variation of the Kondo temperature from 50 K to 300 K at different molecule adsorption sites is revealed. It is shown that the variation is mainly due to the change in the width of d orbital, rather than the shift of its energy. The two-dimensional dI/dV mapping reveals the periodic modulation of the Kondo resonance in the self-assembled MnPc monolayer.