New Internal Stress Driven on-Chip Micromachines for Extracting Mechanical Properties of Thin Films

A new concept of micromachines has been developed for measuring the mechanical properties of thin metallic films. The actuator is a beam undergoing large internal stresses built up during the deposition process. Al thin films are deposited partly on the actuator beam and on the substrate. By etching the structure, the actuator contracts and pulls the Al film. Full stress strain curves can be generated by designing a set of micromachines with various actuator lengths. In the present study, the displacements have been measured by scanning electronic microscopy. The stress is derived from simple continuum mechanics relationships. The tensile properties of Al films of various thicknesses have been tested. A marked increase of the strength with decreasing film thickness is observed.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Raman-scattering study of the phonon dispersion in twisted bi-layer graphene

Bi-layer graphene with a twist angle \theta\ between the layers generates a superlattice structure known as Moir\'{e} pattern. This superlattice provides a \theta-dependent q wavevector that activates phonons in the interior of the Brillouin zone. Here we show that this superlattice-induced Raman scattering can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG). The effect reported here is different from the broadly studied double-resonance in graphene-related materials in many aspects, and despite the absence of stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are observed.Comment: 18 pages, 4 figures, research articl

The Rarita-Schwinger spin-3/2 equation in a nonuniform, central potential

The equations of motion for a massive spin-3/2 Rarita-Schwinger field in a finite-range, central, Lorentz scalar potential are developed. It is shown that the resulting density may not be everywhere positive definite.Comment: 9 pages, RevTe

High-frequency performance of Schottky source/drain silicon pMOS devices

A radio-frequency performance of 85-nm gate-length p-type Schottky barrier (SB) with PtSi source/drain materials is investigated. The impact of silicidation annealing temperature on the high-frequency behavior of SB MOSFETs is analyzed using an extrinsic small-signal equivalent circuit. It is demonstrated that the current drive and the gate transconductance strongly depend on the silicidation anneal temperature, whereas the unity-gain cutoff frequency of the measured devices remains nearly unchanged

Predictions from a stochastic polymer model for the MinDE dynamics in E.coli

The spatiotemporal oscillations of the Min proteins in the bacterium Escherichia coli play an important role in cell division. A number of different models have been proposed to explain the dynamics from the underlying biochemistry. Here, we extend a previously described discrete polymer model from a deterministic to a stochastic formulation. We express the stochastic evolution of the oscillatory system as a map from the probability distribution of maximum polymer length in one period of the oscillation to the probability distribution of maximum polymer length half a period later and solve for the fixed point of the map with a combined analytical and numerical technique. This solution gives a theoretical prediction of the distributions of both lengths of the polar MinD zones and periods of oscillations -- both of which are experimentally measurable. The model provides an interesting example of a stochastic hybrid system that is, in some limits, analytically tractable.Comment: 16 page

Dynamic compartmentalization of bacteria: accurate division in E. coli

Positioning of the midcell division plane within the bacterium E. coli is controlled by the min system of proteins: MinC, MinD and MinE. These proteins coherently oscillate from end to end of the bacterium. We present a reaction--diffusion model describing the diffusion of min proteins along the bacterium and their transfer between the cytoplasmic membrane and cytoplasm. Our model spontaneously generates protein oscillations in good agreement with experiments. We explore the oscillation stability, frequency and wavelength as a function of protein concentration and bacterial length.Comment: 4 pages, 4 figures, Latex2e, Revtex

Red-giant stars in eccentric binaries

The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs

Roughness Analysis In Strained Silicon-on-insulator Wires And Films

Strained silicon is used to enhance performance in state-of-the-art CMOS. Under device operating conditions, the effect of strain is to reduce the carrier scattering at the channel by a smoother semiconductor surface. This has never been completely understood. This paper gives first evidence of the variation in surface roughness under realistic strained conditions. At the nanoscale, the SiO2/Si interface roughness is dependent on the scale of observation (self-affinity). To date, there is no experimental study of the SiO2/Si interface roughness scaling with strain. This work presents the effect of uniaxial and biaxial strains on the surface roughness of strained silicon-on-insulator films and wires using atomic force microscopy. Levels of strain ranging from 0% to 2.3%, encompassing those used in present CMOS devices have been investigated. It is shown that the silicon surface is affected by uniaxial and biaxial strains differently. Three surface roughness parameters have been analyzed: root mean square roughness, correlation length, and the Hurst exponent, which is used to describe the scaling behavior of a self-affine surface. The results show that the root mean square roughness decreases (up to ∼ 40%) with increasing tensile strain, whereas the correlation length increases (up to ∼ 63nm/%) with increasing tensile strain. The Hurst exponent also varies with strain and with the undulation wavelength regime (between ∼ 0.8 and 0.2). This dependency explains why some models used to determine the carrier mobility from experiments fit the data better with a Gaussian form, whereas other models fit the data better with an exponential form.11612EPSRC; Engineering and Physical Sciences Research CouncilSong, Y., Zhou, H., Xu, Q., Luo, J., Yin, H., Yan, J., Zhong, H., (2011) J. Electron. Mater., 40, p. 1584Lee, M.L., Fitzgerald, E.A., Bulsara, M.T., Currie, M.T., Lochtefeld, A., (2005) J. Appl. Phys., 97, p. 011101Chu, M., Sun, Y.K., Aghoram, U., Thompson, S.E., (2009) Annu. Rev. Mater. Res., 39, p. 203Zhao, Y., Takenaka, M., Takagi, S., (2009) IEEE Electron Device Lett., 30, p. 987Cheng, Z.Y., Currie, M.T., Leitz, C.W., Taraschi, G., Fitzgerald, E.A., Hoyt, J.L., Antoniadas, D.A., (2001) IEEE Electron Device Lett., 22, p. 321Rim, K., Hoyt, J.L., Gibbons, J.F., (2000) IEEE Trans. Electron Devices, 47, p. 1406Fischetti, M.V., Gamiz, F., Hansch, W., (2002) J. Appl. Phys., 92, p. 7320Bonno, O., Barraud, S., Mariolle, D., Andrieu, F., (2008) J. Appl. Phys., 103, p. 063715Escobedo-Cousin, E., Olsen, S.H., Pardoen, T., Bhaskar, U., Raskin, J.-P., (2011) Appl. Phys. Lett., 99, p. 241906Pirovano, A., Lacaita, A.L., Ghidini, G., Tallarida, G., (2000) IEEE Electron Device Lett., 21, p. 34Goodnick, S.M., Ferry, D.K., Wilmsen, C.W., Liliental, Z., Fathy, D., Krivanek, O.L., (1985) Phys. Rev. B, 32, p. 8171Mazzoni, G., Lacaita, A.L., Perron, L.M., Pirovano, A., (1999) IEEE Trans. Electron Devices, 46, p. 1423Zhao, Y., Matsumoto, H., Sato, T., Koyama, S., Takenaka, M., Takagi, S., (2010) IEEE Trans. Electron Devices, 57, p. 2057Ishihara, T., Matsuzawa, K., Takayanagi, M., Takagi, S.I., (2002) Jpn. J. Appl. Phys., Part 1, 41, p. 2353Pirovano, A., Lacaita, A.L., Zandler, G., Oberhuber, R., Int. Electron Devices Meet. Tech. Dig., 1999, p. 527Yoshinobu, T., Iwamoto, A., Sudoh, K., Iwasaki, H., (1995) J. Vac. Sci. Technol. B, 13, p. 1630Mandelbrot, B.B., (1982) The Fractal Geometry of Nature: Updated and Augment, , (W. H. Freeman and Company)Pelliccione, M., Lu, T.-M., (2007) Evolution of Thin-film Morphology: Modeling and Simulations, , (Springer, Dordrecht)Zhao, Y.P., Wang, G.C., Lu, T.-M., Graef, M.D., Lucatorto, T., (2000) Characterization of Amorphous and Crystalline Rough Surface: Principles and Applications, , (Elsevier Science)Sinha, S.K., Sirota, E.B., Garoff, S., Stanley, H.B., (1988) Phys. Rev. B, 38, p. 2297Stommer, R., Martin, A.R., Geue, T., Goebel, H., Hub, W., Pietsch, U., (1999) Adv. X-Ray Anal., 41, p. 101Vicsek, T., Cserzo, M., Horváth, V.K., (1990) Physica A, 167, p. 315Arnault, J.C., Knoll, A., Smigiel, E., Cornet, A., (2001) Appl. Surf. Sci., 171, p. 189Bhaskar, U.K., Passi, V., Houri, S., Escobedo-Cousin, E., Olsen, S.H., Pardoen, T., Raskin, J.-P., (2012) J. Mater. Res., 27, p. 571Passi, V., Bhaskar, U.K., Pardoen, T., Sodervall, U., Nilsson, B., Petersson, G., Hagberg, M., Raskin, J.P., (2012) J. Microelectromech. Syst., 21, p. 822Bhaskar, U.K., Pardoen, T., Passi, V., Raskin, J.-P., (2013) Appl. Phys. Lett., 102, p. 031911Liu, X.H., Chen, J., Chen, M., Wang, X., (2002) Appl. Surf. Sci., 187, p. 187Vicsek, T., (1992) Fractal Growth Phenomena, , 2nd ed. (World Scientific)Silva, J.B.D., Jr., Vasconcelos, E.A.D., Santos, B.E.C.A.D., Freire, J.A.K., Freire, V.N., Farias, G.A., Silva, E.F.D., Jr., (2005) Microelectron. J., 36, p. 1011Liu, Z.J., Jiang, N., Shen, Y.G., Mai, Y.W., (2002) J. Appl. Phys., 92, p. 3559Gravier, S., Coulombier, M., Safi, A., Andre, N., Boe, A., Raskin, J.-P., Pardoen, T., (2009) J. Microelectromech. Syst., 18, p. 555Bunshah, R.F., (1994) Handbook of Deposition Technologies for Films and Coatings - Science, Technology and Applications, , 2nd ed. (William Andrew Publishing/Noyes)Ureña, F., Olsen, S.H., Šiller, L., Bhaskar, U., Pardoen, T., Raskin, J.-P., (2012) J. Appl. Phys., 112, p. 114506Ureña, F., Olsen, S.H., Raskin, J.-P., (2013) J. Appl. Phys., 114, p. 144507Ghyselen, B., Hartmann, J.M., Ernst, T., Aulnette, C., Osternaud, B., Bogumilowicz, Y., Abbadie, A., Mazure, C., (2004) Solid-State Electron., 48, p. 1285Lai, L., Irene, E.A., (1999) J. Appl. Phys., 86, p. 1729Schwarzenbach, W., Daval, N., Kerdilès, S., Chabanne, G., Figuet, C., Guerroudj, S., Bonnin, O., Maleville, C., (2012) Proceedings of the IEEE International Conference on Integrated Circuit Design and Technology, , (Austin, TX, USA)Xie, Y.H., Gilmer, G.H., Roland, C., Silverman, P.J., Buratto, S.K., Cheng, J.Y., Fitzgerald, E.A., Citrin, P.H., (1994) Phys. Rev. Lett., 73, p. 3006Michielis, M.D., Conzatti, F., Esseni, D., Selmi, L., (2011) IEEE Trans. Electron Devices, 58, p. 321