Thin film submicrometer

To solve the decrepitation problem, several electrode morphologies and architectures have been explored to accommodate the strain and allow the volume changes to occur without subsequent pulverization. Electrodes composed of micron- and nano-sized particles,thin films,submicrometer pillars, " 3-D porous structures, and various composite anodes have all been explored. It was soon realized that thin films of silicon could accommodate the volume change and be cycled reversibly with little capacity fade, for example, 50 nm thick Si displayed capacities of 3600 mAh/g for 200 cycles. However, these structures fail when the film thickness increases, and also do not have enough active material for a viable battery. These thin film electrodes also critically rely on roughened substrates upon which the vacuum deposited Si can form a quasi-three-dimensional film with columnar-like structures, which can more easily accommodate the lithiation-induced strain and allow the volume expansion compared with a truly planar film. 

Conversion electron Mossbauer spectroscopy (CEMS) measurements with back scattering geometry have the merit that spectra can be obtained from a sample with much less isotope content compared with transmission measurements. Another merit is that a sample, deposited on a thick substrate, could be measured, and that because of the limited escape depth of the conversion electrons, depth-selective surface studies are possible. The CEMS technique was found to be best applicable to specimens of 10-100 pg Au cm, i.e., about two orders of magnitudes thinner than required for measurements in transmission mode [443]. This way (1) very thin films of gold alloys, as well as laser- and in beam-modified surfaces in the submicrometers range of depth [443], and (2) metallic gold precipitates in implanted MgO crystals [444] were investigated. 

The experimental results described above show that the gas-permeability properties of thin glassy polymer films (submicrometer in thickness) are more time- or history-dependent than much thicker films (the bulk state for example, 50 pm or thicker) seem to be. This is manifested in terms of physical aging over a period of 1 year and more. The observed permeability values for the current thin films are all initially greater than the reported bulk values but approach or become less than these values after a few days or weeks, depending on the thickness. After a year, the thin films may be as much as four times less permeable than the reported bulk values. Selectivity increases with aging time, as might be expected from a densification process. 

Figure 10. Self-developed submicrometer images produced in a thin film (0.2 im) of poly(p-tert-butylphenylmethylsilane) by irradiation at 248 nm (55 mjlcm per pulse) to a dose of 550 mjlcm. The images were transferred into 2.0 xm of a hard-baked AZ photoresist by O2-RIE. (Reproduced with permission from reference 63. Copyright 1986 Society of Plastics Engineers.)...

Nobumichi Tamura (left) obtained his Ph.D. in 1993 at the Institut National Polytechnique de Grenoble (INPG) for his work on the structure of quasicrystals and crystalline approximant phases. In 1998 he moved to Oak Ridge National Laboratory to contribute to the development of a new synchrotron-based X-ray microfocus technique capable of resolving strain and texture in thin films with submicrometer spatial resolution. He applied this technique in the field of microelectronics. He is currently staff scientist at the Lawrence Berkeley National Laboratory, where he leads the X-ray microdiffraction project at the Advanced Light Source. His research interest is presently focused on the study of mechanical properties of thin films at mesoscopic scale using synchrotron radiation. 

Heiko O. Jacobs, George M. Whitesides, Submicrometer Patterning of Char ge in Thin-Film Electrets, Science, 291 (2001), 1763-1766. 

AES is sufficiently mature and its application broad. Many general reviews of the technique deal with specific appHcations in general surface and thin film analysis. AES is often used to solve problems in metallurgy, plating, corrosion, and catalysis. Reviews covering these applications are listed in the Further Reading section. Because the primary electron beam can be focused down to a diameter of less than 10 nm, information about local compositions on a specimen s surface can be obtained. This special feature makes AES very attractive for applications in the semiconductor technology where submicrometer features are of interest. To satisfy semiconductor manufacturers, AES systems that are able to handle 300 mm silicon wafers are commercially available now. 

Nagai and co-workers prepared alumina-supported niobium nitride from the eVD of NbCls, using a mixture of NH3 and H2 as a nitridation gas at 823 K under reduced pressure (65). NbN thin film of submicrometer thickness on carbon plate was prepared via the RF-sputtering method (RF power of 2.5 W/cm ) with a Nb plate and N2 atmosphere under vacuum chamber (66). A NbN thin film retained the fine particles of 100 nm. 

Zhang, Z., Ratnayaka, S.N., and Wirth, M.J. Protein UTLC-MALDI-MS using thin films of submicrometer silica particles, J. Chromatogr. A, 1218, 7196-7202, 2011. 

Althongh hardness derived from residual impression measurements is an indicator of the reversible plastic deformation processes, information about elastic release of the indentation depth is mostly lost. Continuous load-displacement monitoring (as the indenter is driven into and withdrawn from the film) sub-stitntes the imaging method nsed in conventional microindenters. The need to characterize the snrface of very thin films and near surfaces has led to the development of nltra- and nanoindentation testers with indentation depths within the submicrometer scale... 

The fabrication of 3D photonic crystals for optical wavelengths is stiU a formidable technological problem, since their structure must have mesoscopic features (comparable to the operating wavelength radiation), and their fabrication accuracy must be at least an order of magnitude better. A number of methods have been proposed for their fabrication [289]. The problem is much simpler with 2D structures where it requires submicrometer photolithography, while in the case of ID crystals it reduces to conventional thin film technologies. 

Aksay and coworkers [20] produced mesoscopic patterning of oriented nan-ostructured silica thin films polymerized by a surfactant-templated sol-gel technique [21] in combination with a micromolding technique, which is another microfabrication technique without photolithography proposed by Xia and Whitesides [19]. A network pattern of microcapillaries (submicrometer scale) was transferred to an elastomeric PDMS stamp as a microreplica molding. An aqueous mixture of tetraethoxysilane and a cationic surfactant (CTAC cetyltri-methylammonium chloride) was introduced into the microcapillaries. After hydrolysis of tetraethoxysilane at the cationic interface of the tubular surfactant assemblies, a mesoscopic supramolecular structure hierarchically constituted from hexagonally packed nanoscopic tubules of silica was formed in the microscopic capillary. 

Vapor phase polymerization from SI-NMP of various vinylic monomers resulted in polymer bmshes with greater thicknesses than those formed by the solution phase process [21]. To explain this result, the authors supposed a more efficient reaction on the surface as a result of prolongation of the mean path of vaporized monomers in a vacuum, higher thermal energy of the monomer, and the possibility of adjusting the reaction parameters independently. Thin films of PS grafted polymer, poly (acrylic acid) (PAA), poly(2-hydroxypropyl methacrylamide) (PHPMA), and poly(lV-isopropylacrylamide) (PNIPAM) were prepared with thicknesses of a few nanometers to submicrometers. This process was also used for the preparation of block copolymers (e.g., PS-b-PAA and PAA-b-PS-PHPMA). It is important to mention that solution phase polymerization of AA, HPMA, and NIPAM is impossible with TEMPO-based alkoxyamines. 

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