Kelvin probe force microscopy was used to study the impact of contacts and topography on the local potential distribution on contacted, individual functionalized graphene sheets (FGS) deposited on a SiO2/Si substrate. Negligible contact resistance is found at the graphene/Ti interface and a graphene resistance of 2.3 k Omega is extracted for a single sheet with sub-mu m size. Pronounced steps in the topography, which we attribute to a variation of the spacing between graphene and substrate, result in a significant change of the local resistivity.
The patterning of ceramic thin films is of great interest for use in MEMS and other applications as discussed in the chapters by Maeda et al. and by Muralt and Baborowski. However, the complex chemistries of certain materials make the use of traditional photolithography techniques prohibitive. In this chapter, a number of low-cost, high throughput techniques for the patterrning of ceramic thin films derived from chemical solution precursors, such as sol-gels and ceramic slurries, are presented. Most of these methods are derived from soft lithographic methods using elastomer molds, a method that is categorized as the next generation lithography in the chapter by Alexe et al. Two categories of techniques are discussed: first, the focus is on methods that rely on the principles of confinement within the physical features of the mold to define the pattern on the substracte surface. Then, subtractive patterning techniques that rely on transferring a pattern to a spin-cast large-area continuous thin film are described. Most techniques have been demonstrated with fidelities on the order of 100 nm; however, their inability to precisely register and align the patterns as part of a hierarchical fabrication scheme has hindered their commercial implementation thus far. This chaper has been updated from the original manuscript to reflect the most recent available literature and complements the chapter by Baborowshi on pattern formation by micromachining techniques.
Barium titanate can be hydrothermally synthesized by exposing a titanium source to a Ba(OH)(2) solution. In concentrated solutions, time resolved studies indicated that BaTiO3 particles nucleate, grow and agglomerate to form 'raspberry-like' clusters which gradually rearrange to form single crystal BaTiO3 particles. Polymer films containing barium titanate particles can also be produced by a hydrothermal route. Titanium organometallic precursor is dissolved in polymer solutions and spun-cast into films. BaTiO3 is formed in the polymer matrix upon exposure to Ba(OH)(2) solution at temperatures below 100 degrees C. Two modifications to this approach are described which alter the morphology of the BaTiO3 particles utilizing the tendency of the block copolymer matrix to microphase separate. Patterning of the BaTiO3 by redistribution of the precursor in the block copolymer matrix may provide a method of producing 0-3, 1-3 and 2-2 connectivities.
Slamovich, E. B. ; Aksay, I. A.Hydrothermal processing of BaTiO3 polymer-films. In Better Ceramics through Chemistry Vi; Cheetham, A. K. ; Brinker, C. J. ; Mecartney, M. L. ; Sanchez, C., Ed. Materials Research Soc: Pittsburgh, 1994; Vol. 346, pp. 63-68.
Keckler, S. E. ; Dabbs, D. M. ; Yao, N. ; Aksay, I. A.Silification of wood-cell walls. In Fifty-Second Annual Meeting - Microscopy Society of America/Twenty-Ninth Annual Meeting - Microbeam Analysis Society, Proceedings; Bailey, G. W. ; GarrattReed, A. J., Ed. San Francisco Press Inc: San Francisco, 1994; pp. 428-429.
Dabbs, D. M. ; Yao, N. ; Aksay, I. A.Surfactant Mediated Deformation of Gold Particles. In Fifty-Second Annual Meeting - Microscopy Society of America/Twenty-Ninth Annual Meeting - Microbeam Analysis Society, Proceedings; Bailey, G. W. ; GarrattReed, A. J., Ed. San Francisco Press Inc: San Francisco, 1994; pp. 446-447.
McGehee, M. D. ; Gruner, S. M. ; Yao, N. ; Chun, C. M. ; Navrotsky, A. ; Aksay, I. A.Synthesis of Mesoscopic Structures by Co-assembly. In Fifty-Second Annual Meeting - Microscopy Society of America/Twenty-Ninth Annual Meeting - Microbeam Analysis Society, Proceedings; Bailey, G. W. ; GarrattReed, A. J., Ed. San Francisco Press Inc: San Francisco, 1994; pp. 448-449.