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Selective Patterning (selective + patterning)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Selective patterning of covalent molecular grafting on doped amorphous silicon templates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Hussein Sabbah
Abstract Linear alkene molecules have been covalently immobilized on amorphous silicon surfaces. The larger thermal reactivity of n+ -doped vs. nominally undoped a-Si:H surfaces towards perfluorodecene (PFD) molecules in the gas phase has been exploited to investigate a selective patterning of molecular grafting on a previously defined template of doped / undoped regions. PFD has been chosen to obtain hydrophobic monomolecular layers with fluorine labelling, useful for photoelectron spectroscopy (XPS) and NanoSIMS imaging. The template was obtained by growing undoped a-Si:H on top of n+ a-Si-H, and defining 40 ,m-edge patterns of undoped a-Si:H by reactive ion etching in a (CF4, O2) mixture. After native oxide removal, the patterned surface was exposed to PFD at 230 °C. NanoSIMS images, taken at increasing Cs+ irradiation doses, show the expected 19F and 28Si contrast on as-grafted surfaces; this contrast disappears after ,340 seconds Cs+ irradiation, corresponding to the desorption of the PFD monomolecular layer. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Laser-induced crystal growth of nonlinear optical Ba3Ti3O6(BO3)2 on glass surface

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008
T. Oikawa
Abstract Nonlinear optical Ba3Ti3O6(BO3)2 crystals were patterned on the surface of CuO (1 mol%)-doped 40BaO-40TiO2 -20B2O3 glass by irradiations of continuous-wave Nd:YAG (wavelength: ,=1064 nm) and Yb:YVO4 (,=1080 nm) lasers. Laser energies absorbed by Cu2+ ions were transferred to the lattice system through a nonradiative relaxation process, consequently heating the glass and inducing local crystallizations. For the lines patterned by Yb:YVO4 laser irradiations with a power of 1 W and a scanning speed of 20 ,m/s, a c -axis orientation of Ba3Ti3O6(BO3)2 crystals along the laser scanning direction is proposed from measurements of X-ray diffraction analyses, polarized optical photographs, polarized micro-Raman scattering spectra, and azimuthal dependence of second harmonic generations. The laser-induced crystallization technique is found to be applied successfully for the spatially selective patterning of nonlinear optical Ba3Ti3O6(BO3)2 crystals in glass. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Chemically selective soft X-ray patterning of polymers

JOURNAL OF SYNCHROTRON RADIATION, Issue 2 2007
Jian Wang
The chemically selective modification of polymer mixtures by monochromated soft X-rays has been explored using the high-brightness fine-focused 50,nm beam of a scanning transmission X-ray microscope. Four different polymer systems were examined: a polymethylmethacrylate (PMMA) polyacrylonitrile (PAN) bilayer film; a PMMA- blend -PAN microphase-separated film; a poly(MMA- co -AN) copolymer film; and a poly(ethyl cyanoacrylate) homopolymer film. A high level of chemically selective modification was achieved for the PMMA/PAN bilayer; in particular, irradiation at 288.45,eV selectively removed the carbonyl group from PMMA while irradiation at 286.80,eV selectively reduced the nitrile group of PAN, even when these irradiations were carried out at the same (x,y) position of the sample. In the last two homogenous polymer systems, similar amounts of damage to the nitrile and carbonyl groups occurred during irradiation at either 286.80 or 288.45,eV. This is attributed to damage transfer between the C[triple-bond]N and C=O groups mediated by primary electrons, secondary electrons or radical/ionic processes, aided by their close spatial proximity. Although the overall thickness of the bilayer sample at 70,nm is smaller than the lateral line spreading of 100,nm, the interface between the layers appears to effectively block the transport of energy, and hence damage, between the two layers. The origins of the line spreading in homogeneous phases and possible origins of the damage blocking effect of the interface are discussed. To demonstrate chemically selective patterning, high-resolution multi-wavelength patterns were created in the PMMA/PAN bilayer system. [source]

Selective patterning of covalent molecular grafting on doped amorphous silicon templates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Hussein Sabbah
Abstract Linear alkene molecules have been covalently immobilized on amorphous silicon surfaces. The larger thermal reactivity of n+ -doped vs. nominally undoped a-Si:H surfaces towards perfluorodecene (PFD) molecules in the gas phase has been exploited to investigate a selective patterning of molecular grafting on a previously defined template of doped / undoped regions. PFD has been chosen to obtain hydrophobic monomolecular layers with fluorine labelling, useful for photoelectron spectroscopy (XPS) and NanoSIMS imaging. The template was obtained by growing undoped a-Si:H on top of n+ a-Si-H, and defining 40 ,m-edge patterns of undoped a-Si:H by reactive ion etching in a (CF4, O2) mixture. After native oxide removal, the patterned surface was exposed to PFD at 230 °C. NanoSIMS images, taken at increasing Cs+ irradiation doses, show the expected 19F and 28Si contrast on as-grafted surfaces; this contrast disappears after ,340 seconds Cs+ irradiation, corresponding to the desorption of the PFD monomolecular layer. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]