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MEMS, NANO and Smart Systems, 2005. Proceedings. 2005 International Conference on

Date 24-27 July 2005

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  • Proceedings. 2005 International Conference on MEMS, NANO and Smart Systems

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  • 2005 International Conference on MEMS,NANO and Smart Systems - Title Page

    Page(s): i - iii
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  • 2005 International Conference on MEMS,NANO and Smart Systems - Copyright

    Page(s): iv
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  • 2005 International Conference on MEMS,NANO and Smart Systems - Table of contents

    Page(s): v - xiv
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  • Preface

    Page(s): xv
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  • Conference Committee

    Page(s): xvi - xxiv
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  • Novel one dimensional nanostructures

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    Summary form only given, as follows: the combination of remarkable mechanical properties and unique electronic properties of carbon nanotubes (CNTs) offers significant potential for revolutionary applications in electronics devices, computing and data storage technology, chemical and biosensors, composites, nanoelectromechanical systems (NEMS), and as tip in scanning probe microscopy (SPM) for imaging and nanolithography, most of-which are the subject areas of ICMENS2005. The ability to grow inorganic nanowires with controlled properties and orientation provides another competitive avenue for some of the applications mentioned above particularly in sensors and electronics. In this talk growth and characterization of both CNTs and inorganic nanowires such as germanium and high temperature oxides will be discussed with a focus on the applications. View full abstract»

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  • The intrinsic spin Hall effect

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    Summary form only given, as follows: a recent theory predicts that dissipationless spin currents can be induced purely by an electric field in conventional semiconductors. The dissipationless spin current is derived from a novel topological structure in momentum space, is independent of the sample disorder and leads to the intrinsic spin Hall effect. In hole doped semiconductors, with or without inversion symmetry breaking, there are no vertex corrections due to impurities scattering, and there are no extrinsic contributions to the spin Hall effect in the clean limit. The author analyzes a recent experiment on the spin Hall effect, and shows that it is consistent with the intrinsic nature of the effect. The author also shows that the spin Hall effect can be quantized in semiconductors with appropriate strain gradients, but in the absence of any external magnetic fields or the associated time reversal symmetry breaking. View full abstract»

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  • Efficient spin injection using tunnel injectors

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    Summary form only given, as follows: semiconductor spintronics aims to develop novel sensor, memory and logic devices by manipulating the spin states of carriers in semiconducting materials. This talk will focus on electrical spin injection into semiconductors, which is a prerequisite for spintronics and, in particular, on tunnel based spin injectors that are potentially operable above room temperature. The spin polarization of the electron current within the semiconductor is detected by measuring the circular polarization of the electroluminescence from a quantum well light emitting diode structure. The temperature and bias dependence of the electroluminescence polarization provides insight into the spin relaxation mechanisms within the semiconductor heterostructure. View full abstract»

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  • Spin-transfer induced switching in magnetic nanopillars

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    Summary form only given, as follows: the author reviews the basic experimental findings of spin-induced magnetic switching in sub-100 nm magnetic nanopillar spin valves. Issues include the basic physics of a spin-current-induced torque on a nanomagnet, sample fabrication techniques, and device properties in terms of current-induced magnetic excitation and magnetic switching dynamics. Potentials for future applications in magnetic memory technology and related challenges will also be briefly discussed. View full abstract»

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  • Injecting and controlling spin populations and currents in semiconductors using optically induced quantum interference effects

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    Summary form only given. This paper reviews the recent developments of epitaxial ferromagnetic heterostructures based on semiconductors for spintronics. The magnetotransport of prepared ferromagnetic III-V semiconductor heterostructures (Mn-delta-doped GaAs/Be-doped AlGaAs) and the control of ferromagnetism in the heterostructures by using gate electric field and light irradiation at relatively high Curie temperature (TC) (∼100 K) are also studied. This paper proposes and theoretically analyzes a spin MOSFET consisting of a MOS gate and ferromagnetic contacts for the source and drain. The spin MOSFET has large magnetocurrent ratios (spin dependent transport similar to the GMR or TMR devices), high transconductance (gm), and good compatibility with CMOS technology, which are very important for integrated circuit applications. View full abstract»

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  • Instability of submicron anisotropic liquid cylinders and jets in magnetic field

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    The capillary instability of a magnetically anisotropic liquid cylinder and jets, such as Nematic liquid crystals (LC), in magnetic fields, is considered using an energy approach. The boundary problem is solved in the linear approximation of the anisotropy χa of the magnetic susceptibility χ. The effect of the anisotropy, in the region 1 |χ|>| χa| χ2, can be strong enough to counteract and even reverse the tendency of the field to enhance stabilization by increasing the cut-off wave number ks, beyond the conventional one set by Rayleigh. It is shown that the elastic effect, which is typical of LC, is significant on the scale of nano-jets, where it prevails over the magnetic effect. The jet instability is determined by surface tension, elasticity, and magnetic permeability and anisotropy. The relative influence of the elasticity and permeability on the jet stability depends on its radius. This is particularly true on the nano-scale. View full abstract»

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  • On the effect of cationic surfactants in the rinse to reduce pattern collapse in high aspect ratio patterning of photoresists

    Page(s): 14 - 15
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    This paper presents a novel concept based on the mechanism of cationic surfactant adsorption on the photoresist surface. The minimum capillary forces calculated from the study with model photoresist surfaces and surfactant solutions correlated with a maximum of pattern collapse reduction obtained in the photolithographic process. View full abstract»

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  • A disjoining pressure isotherm for curved, interfacial boundaries

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    Summary form only given, as follows: the disjoining pressure (DP) concept was introduced as an explanation for the excess pressure that must be applied to offset the tendency of the film phase to separate or disjoin from the confining bulk phases. It is considered to be a function of the separation distance between the confining phases with expressions for dispersion, electrostatic, structural and steric components. These component expressions permit DP isotherms, as a function of separation, to be calculated. In this paper an alternative approach is adopted whereby the energy of the film is allowed to possess a greater functional dependence (i.e. both separation and radial distance dependence). A variational approach to obtain an Euler-Lagrange equation for the DP isotherm and its local and global equilibrium structure shows that the isotherm has specific functional forms that are limited when subjected to geometric constraints (i.e. solid boundary). View full abstract»

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  • Influence of solid-liquid-liquid interactions on multiphase transport behavior in porous media

    Page(s): 17 - 18
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    This paper examines the effect of two types of surfactants (one nonionic and the other anionic) on wettability and multiphase flow characteristics by conducting contact angle measurements and flow tests through porous media using three different rock-fluids systems. The contact angle measurements have been made using the Dual-Drop Dual-Crystal (DDDC) technique and the multiphase flow characteristics are reported as oil-water relative permeabilities computed using a simulator by history matching the pressure drop and production data obtained during flow tests. View full abstract»

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  • Non-invasive mapping of fluid temperature and flow in microsystems

    Page(s): 21 - 26
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    Currently available temperature and fluid flow measurement methods have shown limitations in microscale systems. This research concerns the development of a non-invasive optical measurement technique and sensor for mapping two-dimensional temperature fields and, ultimately fluid flows. The system is based on the Shack-Hartmann wave-front sensor. Analytical considerations underlying the mapping technique and preliminary experimental results are presented. Two experimental rigs involved in this study are also discussed. View full abstract»

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  • Avery Dennison micro-nano replication capabilities for MEMS and microfluidics

    Page(s): 27 - 29
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    Polymers can be used as one of most promising materials for MEMS applications. In this paper, we successfully demonstrated embossing micro-nano structures on polymers, especially high temperature polymers (>300°C) by using Avery's unique proprietary embossing technology. Also in this paper, we demonstrated a roll-to-roll embossing/lamination method for manufacturing low cost plastic microfluidics devices. View full abstract»

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  • A parametric study of thermal effects on the reliability of RF MEMS switches

    Page(s): 30 - 31
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    The influence of thermal effects on the reliability of RF MEMS switches is investigated in this paper. Low power consumption and capacity to handle high power at very high frequency elevate the scope of RF MEMS in the field of satellite and mobile communication technology immensely. The reliability of these switches are still under consideration as they fail due to thermal stresses developed during operation. A significant temperature rise occurs while transmitting high power at high frequency. In this paper, we introduced design parameters and investigated their influence to improve the switch's resistance to acute thermal stresses. A three dimensional finite element model of RF MEMS switch was simulated. A current density model and a thermal model were coupled to calculate the current density, heat loss and temperature rise within the domain. The maximum frequency and power range that the switch can handle before buckling failure were estimated. View full abstract»

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  • Optimization of turn geometries in microfluidic channels

    Page(s): 32 - 35
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    Microfluidic separation systems often use channels with turns to achieve long separation distance within a compact region. But the bends or curves degrade the performance of separation efficiency. To tackle this problem, channels are modeled with different types of 90 degree turns to reduce the "racetrack" effect. In this paper, the finite element method is used to numerically solve the equations governing electroosmotic flow and mass transport in a microchannel. The detailed results show that the sample plug broadening due to turns can be reduced when the outside of the turn is dented. It is also suggested that the band tilting can be corrected. View full abstract»

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  • Spin polarized transport effects in III-V semiconductor heterostructures

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    Summary form only given. In the field of spintronics, GaMnAs, a ferromagnetic semiconductor, offers many advantages to study tunnel magnetotransport properties when used as an electrode. The complexity of the transport mechanisms associated with spin orbit coupled states make this material a powerful means for finding novel effects; also it provides new challenges for a theoretical understanding. This includes the tunnel magnetoresistance (TMR) across single or double barriers, tunneling anisotropic magnetoresistance (TAMR) and current induced magnetic switching (CIMS), as recently reported in such systems. I will discuss on the basis of magnetoresistance experiments with tunnel junctions the key elements to observe and understand such effects. View full abstract»

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  • Injecting and controlling spin populations and currents in semiconductors using optically induced quantum interference effects

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    It is widely known that interband optical excitation of semiconductors such as GaAs using circularly polarized light can induced a net electron spin polarization because of the spin-orbit interaction which modifies the valence band states. In the last few years we have undertaken a series of theoretical and experimental investigations to explore how all-optical processes can be used to inject and control not only pure spin populations but also pure spin currents and pure charge currents or combinations of these. The various excitation schemes can be understood in terms of quantum interference of absorption pathways or, on a macroscopic level, nonlinear optical processes. The controlled currents and spin populations are typically generated by femtosecond laser pulses and detected via pump-probe techniques based on induced transmission changes or emitted THz radiation. View full abstract»

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  • Spinwaves in spintronics structures

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    We have been applying in situ and ex situ spin-wave Brillouin Light Scattering (BLS) techniques to spinwave structures we are growing by Molecular Beam Epitaxy (MBE). The sensitivity of our BLS technique is illustrated by our ability to measure spin-wave excitations for samples as thin as 1 monolayer of Co buried by as much as 20 nanometers of Au. This talk will describe the use of in situ and ex situ BLS in combination with appropriate structural probes to determine the origin of several interesting and useful physical phenomena in spintronics structures. View full abstract»

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  • Ferromagnetic III-V semiconductor films with high transition temperature

    Page(s): 42 - 44
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    The fabrication process of the GaAs-based materials included the deposition of the (Ga,Mn)As alloy at low temperature by conventional solid-source molecular beam epitaxy (MBE) and subsequent thermal annealing. The ferromagnetic and paramagnetic phases are found to coexist in the whole temperature range below Tc. Rapid thermal annealing turns the ferromagnetic (Ga,Mn)As into a paramagnetic matrix. The structural and magnetic properties of granular films prepared by using different annealing recipes have been investigated by X-ray diffraction, superconducting quantum interference device magnetometry, and transmission electron microscopy. The temperature dependence of the lattice parameter a of the nanoclusters also exhibits a significant variation around the bulk MnAs phase transition temperature. View full abstract»

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  • New trends in rough surface characterization: when the wrinkle is beautiful

    Page(s): 47 - 48
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    The rough material can improve the friction, the adhesion, as well as reduce the wetting which were characterised by Brownian surface. The work is to analyse the possible relationship between different classical roughness parameters, the maximum surface amplitude, the Hurst exponent, the lacunarity. The topographies were obtained using the atomic force microscopy. View full abstract»

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  • Superhydrophobic behavior of a microtextured surface: a thermodynamic approach

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    A pillar microtexture, which has been intensively investigated in experiments, is chosen as a typical example and thermodynamically analyzed in detail. To gain a comprehensive insight into superhydrophobic behavior, the roles of pillar height, width and spacing (or roughness and solid fraction), intrinsic CA, drop size, and vibrational energy as well as fractal structure and formation of liquid films are systematically investigated. Solid surface fraction is shown by f. Free energy (FE) and free energy barrier (FEB) are calculated using a simple and robust 2D model. Based on the calculations of FE and FEB, various CAs, including apparent, equilibrium (stable), advancing and receding CAs, and CA hysteresis (CAH) can be determined. Especially, the design of practical surephydrophobic surfaces is emphasized in connection with the transition between noncomposite and composite states; a criterion for judging such transition is proposed. The theoretical results are consistent with Wenzel's and Cassie's equations and experimental observations. Furthermore, based on these results and the proposed criterion, some general principles to achieve superhydrophobic performance are suggested. View full abstract»

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