BioMedical Physics

IBMM of OH adsorbates and interphases on Si-based materials

by Nicole Herbots

N. Herbots , Qian Xing, M. Hart, J.D. Bradley, D.A. Sell, R.J. Culbertson, Barry J. Wilkens
Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA
FINAL REFERENCE:
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Volume 272, 1 February 2012, Pages 330-333

Proceedings of the 17th International Conference on Ion Beam Modification of Materials (IBMM 2010)

Please cite this article as

N. Herbots. Q. Xing et al., IBMM of OH adsorbates and interphases on Si-based materials, Nucl. Instr. and Meth. , Vol 272, pp 330-333 (2012),
doi:10.1016/j.nimb.2011.01.094

Using ion beam modification, films composed of synthesized
‘‘interphases’’ of ordered silica on OH-passivated (1... more Using ion beam modification, films composed of synthesized
‘‘interphases’’ of ordered silica on OH-passivated (1 X 1) Si(100) underwent surface electro-chemical changes quantified by surface free energy via Sessile drop method and contact angle analysis using Young’s equation and Van Oss theory. IBMM caused the surface free energies initially ranging from 26.0 mJ/m2 to 57.3 mJ/m2 to converge to 43.1–45.4 mJ/m2 for various passivated and as-received wafer samples alike. Although TMAFM also identified topographic changes, these changes did not correlate to the change of surface free energies. Ion beam modification of the ordered silica film on Si(100) surface is analyzed using 3.045 MeV 16O(a, a)16O nuclear resonance scattering (NRS) in conjunction with channeling in (1 1 1) direction, which demonstrated the convergence of the partially ordered oxygen to amorphous at about 55 microCoulombs/mm2 He++ flux. Additionally, Si surface peak channeling in (1 0 0) and (1 1 1) directions also experienced an uptrend in areal density as incident ion flux increased, while the rotating random Si signal height remains stable, showing a disruption in the surface order during IBMM.

Ion Beam Analysis Of Silicon Based Surfaces And Correlation With Surface Energy Measurements

by Nicole Herbots

Qian Xing, N. Herbots, M. Hart, J. D. Bradley, B. J. Wilkens, D. A. Sell, Clive H. Sell, Henry Mark Kwong Jr., R. J. Culbertson, S. D. Whaley

Department of Physics, Arizona State University, Tempe, AZ 85287-1504
Associated Retina Consultants, 7600 N 15th Street, Suite 155, Phoenix, AZ 85020

Citation: AIP Conf. Proc. 1336, 201 (2011); doi: 10.1063/1.3586089

The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain... more The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain hydrophobic or hydrophilic behavior of silicone, silicates, and silicon surfaces. Surface defects such as dangling bonds, surface free energy including Lewis acid-base and Lifshitz-van der Waals components are discussed. Water nucleation and condensation is further explained by surface topography. Tapping mode atomic force microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces. The correlation of the above two characteristics describes the behavior of water condensation at Si-based surfaces. Surface root mean square roughness increasing from several Å to several nm is found to provide nucleation sites that expedite water condensation visibly for silica and silicone. Hydrophilic surfaces have a condensation pattern that forms puddles of water while hydrophobic surfaces form water beads. Polymer adsorption on these surfaces alters the water affinity as well as the surface topography, and therefore controls condensation on Si-based surfaces including silicone intraocular lens (IOL). The polymer film is characterized by Rutherford backscattering spectrometry (RBS) in conjunction with 4.265 MeV 12C(α, α)12C, 3.045 MeV 16O(α, α)16O nuclear resonance scattering (NRS), and 2.8 MeV elastic recoil detection (ERD) of hydrogen for high resolution composition and areal density measurements. The areal density of hydroxypropyl methylcellulose (HPMC) film ranges from 1018 atom/cm2 to 1019 atom/cm2 gives the silica or silicone surface a roughness of several Å and a wavelength of 0.16 ± 0.02 μm, and prevents fogging by forming a complete wetting layer during water condensation.
Keywords: ERD, NRS, RBS, AFM, polymer film, silicone, silica, Si(100), contact angle, surface free energy, surface topography, intraocular implant.

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Trabajo Académicamente Dirigido por Jose Manuel Udías Moinelo