The Experts below are selected from a list of 9033 Experts worldwide ranked by ideXlab platform
G Scoles - One of the best experts on this subject based on the ideXlab platform.
-
structure of pentacene thin films
Applied Physics Letters, 2004Co-Authors: Ricardo Ruiz, Bert Nickel, G Scoles, Alex C Mayer, George G Malliaras, A Kazimirov, Randall L Headrick, Zahirul IslamAbstract:Grazing incidence x-ray diffraction, x-ray reflectivity and atomic force microscopy have been performed to study the structure of pentacene thin films on Oxidized Si substrates from submonolayer to multilayer coverages. The volume of the unit cell in the thin film phase is almost identical to that of the bulk phase, thus the molecular packing efficiency is effectively the same in both phases. The structure forming from the first monolayer remains the same for films at least 190A thick. The in-plane structure of the submonolayer islands also remains unchanged within a substrate temperature range of 0
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 μm - 2 . Second monolayer (ML) formation starts at a coverage of Θ=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 μm - 2 ). Second ML formation also starts at Θ=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}.$ Second monolayer (ML) formation starts at a coverage of \ensuremath{\Theta}=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}).$ Second ML formation also starts at \ensuremath{\Theta}=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
Ricardo Ruiz - One of the best experts on this subject based on the ideXlab platform.
-
structure of pentacene thin films
Applied Physics Letters, 2004Co-Authors: Ricardo Ruiz, Bert Nickel, G Scoles, Alex C Mayer, George G Malliaras, A Kazimirov, Randall L Headrick, Zahirul IslamAbstract:Grazing incidence x-ray diffraction, x-ray reflectivity and atomic force microscopy have been performed to study the structure of pentacene thin films on Oxidized Si substrates from submonolayer to multilayer coverages. The volume of the unit cell in the thin film phase is almost identical to that of the bulk phase, thus the molecular packing efficiency is effectively the same in both phases. The structure forming from the first monolayer remains the same for films at least 190A thick. The in-plane structure of the submonolayer islands also remains unchanged within a substrate temperature range of 0
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 μm - 2 . Second monolayer (ML) formation starts at a coverage of Θ=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 μm - 2 ). Second ML formation also starts at Θ=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}.$ Second monolayer (ML) formation starts at a coverage of \ensuremath{\Theta}=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}).$ Second ML formation also starts at \ensuremath{\Theta}=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
K Hono - One of the best experts on this subject based on the ideXlab platform.
-
l10 ordered high coercivity fept ag c granular thin films for perpendicular recording
Journal of Magnetism and Magnetic Materials, 2010Co-Authors: Li Zhang, A Perumal, Y K Takahashi, K HonoAbstract:Abstract We report (FePt)Ag–C granular thin films for potential applications to ultrahigh denSity perpendicular recording media, that were processed by co-sputtering FePt, Ag, and C targets on MgO underlayer depoSited on thermally Oxidized Si substrates. (FePt) 1− x Ag x – y vol%C (0 x y o C. We found that the Ag additions improved the L 1 0 ordering and the granular structure of the FePt–C films with the perpendicular coercivity ranging from 26 to 37 kOe for the particle Size of 5–8 nm. The (FePt) 0.9 Ag 0.1 –50vol%C film showed the optimal magnetic properties as well as an appropriate granular morphology for recording media, i.e., average grain Size of D av =6.1 nm with the standard deviation of 1.8 nm.
-
spin polarization of co fe alloys estimated by point contact andreev reflection and tunneling magnetoreSistance
Journal of Applied Physics, 2009Co-Authors: S V Karthik, T M Nakatani, A Rajanikanth, Yoshihiro Takahashi, K HonoAbstract:The compoSitional dependence on spin polarization of Co100−xFex alloys has been studied by point contact Andreev reflection (PCAR) and tunneling magnetoreSistance (TMR) measurements. The intrinSic spin polarization for bcc Co75Fe25 alloy is P=0.58±0.03 at 4.2K contrary to the pure Fe (P=0.46±0.03) and Co (P=0.45±0.03). The tunneling spin polarization values of Co75Fe25 (110) textured polycrystalline electrode and (001) epitaxially grown electrode was estimated to be PT=0.5±0.01 and PT=0.57±0.01 at 8K from the TMR ratios uSing Julliere’s model for the MTJs prepared on Oxidized Si and MgO (001) substrates. The spin polarization obtained from the tunneling junctions and PCAR experiments have been discussed.
-
l10 fept c nanogranular perpendicular anisotropy films with narrow Size distribution
Applied Physics Express, 2008Co-Authors: A Perumal, Y K Takahashi, K HonoAbstract:We report the study of L10 FePt–C nanogranular perpendicular anisotropy films fabricated on Oxidized Si substrates with a (100) textured MgO intermediate layer. The addition of a small amount of C (<12%) to a FePt (4 nm) film results in the formation of interconnected FePt particles, while a higher C addition leads to the formation of well-isolated L10 FePt nanoparticles with a c-axis texture. The FePt particle Size can be reduced to 5.5 nm with a Size distribution of 2.3 nm in variance by adjusting FePt thickness. Perpendicular coercivity is controllable between 8 and 15 kOe with high squareness. These results demonstrate that the FePt–C system can accomplish a nanogranular structure suitable for ultrahigh denSity perpendicular recording media.
-
particulate structure of l10 ordered ultrathin fept films for perpendicular recording
Applied Physics Letters, 2008Co-Authors: A Perumal, Y Takahashi, Tomoko Seki, K HonoAbstract:We report the investigation of microstructure and magnetic properties of ultrathin FePt (1–10nm) films grown on Oxidized Si substrates with a 10nm MgO(100) intermediate layer. The isolated FePt particles with high degree of L10 ordering and large magnetocrystalline anisotropy could be fabricated with a thickness of less than 5nm. Perpendicular coercivity of isolated FePt particles is controllable between 15 and 25kOe. These results are promiSing and highly deSirable for magnetic recording applications.
Bert Nickel - One of the best experts on this subject based on the ideXlab platform.
-
structure of pentacene thin films
Applied Physics Letters, 2004Co-Authors: Ricardo Ruiz, Bert Nickel, G Scoles, Alex C Mayer, George G Malliaras, A Kazimirov, Randall L Headrick, Zahirul IslamAbstract:Grazing incidence x-ray diffraction, x-ray reflectivity and atomic force microscopy have been performed to study the structure of pentacene thin films on Oxidized Si substrates from submonolayer to multilayer coverages. The volume of the unit cell in the thin film phase is almost identical to that of the bulk phase, thus the molecular packing efficiency is effectively the same in both phases. The structure forming from the first monolayer remains the same for films at least 190A thick. The in-plane structure of the submonolayer islands also remains unchanged within a substrate temperature range of 0
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 μm - 2 . Second monolayer (ML) formation starts at a coverage of Θ=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 μm - 2 ). Second ML formation also starts at Θ=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
-
pentacene ultrathin film formation on reduced and Oxidized Si surfaces
Physical Review B, 2003Co-Authors: Ricardo Ruiz, Bert Nickel, Norbert Koch, L C Feldman, R F Haglund, Antoine Kahn, G ScolesAbstract:We have compared the nucleation of pentacene on reduced and Oxidized Si surfaces by a combination of x-ray reflectivity measurements and atomic force microscopy. For the reduced surface, the nucleation denSity is 0.007 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}.$ Second monolayer (ML) formation starts at a coverage of \ensuremath{\Theta}=0.6 ML, and the first layer is completely closed at a total coverage of 2 ML. For the Oxidized surface, the nucleation denSity is larger by a factor of 100 (0.7 $\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}2}).$ Second ML formation also starts at \ensuremath{\Theta}=0.6 ML, but the first layer closes already at 1.1 ML coverage, indicating nearly ideal layer-by-layer growth. For both terminations, the electron denSity obtained for the closed first monolayer is only 75% of the bulk value, indicating a reduced mass packing efficiency of the layer. Second ML islands are aligned relative to each other on an area limited by the lateral Size of first ML islands, which act as templates for epitaxial growth.
Lucio Colombi Ciacchi - One of the best experts on this subject based on the ideXlab platform.
-
development of a clasSical force field for the Oxidized Si surface application to hydrophilic wafer bonding
Journal of Chemical Physics, 2007Co-Authors: Daniel J Cole, M C Payne, Mark S Spearing, Gabor Csanyi, Lucio Colombi CiacchiAbstract:We have developed a clasSical two- and three-body interaction potential to Simulate the hydroxylated, natively Oxidized Si surface in contact with water solutions, based on the combination and extenSion of the Stillinger-Weber potential and of a potential originally developed to Simulate SiO2 polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tenSile surface stress, and interactions with Single water molecules of a natively Oxidized Si surface model previously obtained by means of accurate denSity functional theory Simulations. We have applied the potential to the case of hydrophilic Silicon wafer bonding at room temperature, revealing maximum room temperature work of adheSion values for natively Oxidized and amorphous Silica surfaces of 97 and 90mJ∕m2, respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively Oxidized surface with liquid water, resulting in a higher heat of immerSio...
-
development of a clasSical force field for the Oxidized Si surface application to hydrophilic wafer bonding
Journal of Chemical Physics, 2007Co-Authors: Daniel J Cole, M C Payne, Mark S Spearing, Gabor Csanyi, Lucio Colombi CiacchiAbstract:We have developed a clasSical two- and three-body interaction potential to Simulate the hydroxylated, natively Oxidized Si surface in contact with water solutions, based on the combination and extenSion of the Stillinger-Weber potential and of a potential originally developed to Simulate SiO(2) polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tenSile surface stress, and interactions with Single water molecules of a natively Oxidized Si surface model previously obtained by means of accurate denSity functional theory Simulations. We have applied the potential to the case of hydrophilic Silicon wafer bonding at room temperature, revealing maximum room temperature work of adheSion values for natively Oxidized and amorphous Silica surfaces of 97 and 90 mJm(2), respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively Oxidized surface with liquid water, resulting in a higher heat of immerSion (203 vs 166 mJm(2)), and may be explained in terms of the more pronounced water structuring close to the surface in alternating layers of larger and smaller denSities with respect to the liquid bulk. The computed force-displacement bonding curves may be a useful input for coheSive zone models where both the topographic details of the surfaces and the dependence of the attractive force on the initial surface separation and wetting can be taken into account.
