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- All Subjects: Surface Energy
- Creators: Culbertson, Robert
Description
Water affinity and condensation on Si-based surfaces is investigated to address the problem of fogging on silicone intraocular lenses (IOL) during cataract surgery, using Si(100), silica (SiO2) and polydimethylsiloxane (PDMS) silicone (SiOC2H6)n. Condensation is described by two step nucleation and growth where roughness controls heterogeneous nucleation of droplets followed by Ostwald ripening. Wetting on hydrophilic surfaces consists of continuous aqueous films while hydrophobic surfaces exhibit fogging with discrete droplets. Si-based surfaces with wavelength above 200 nm exhibit fogging during condensation. Below 200 nm, surfaces are found to wet during condensation. Water affinity of Si-based surfaces is quantified via the surface free energy (SFE) using Sessile drop contact angle analysis, the Young-Dupré equation, and Van Oss theory. Topography is analyzed using tapping mode atomic force microscopy (TMAFM). Polymer adsorption and ion beam modification of materials (IBMM) can modify surface topography, composition, and SFE, and alter water affinity of the Si-based surfaces we studied. Wet adsorption of hydroxypropyl methylcellulose (HPMC) C32H60O19 with areal densities ranging from 1018 atom/cm2 to 1019 atom/cm2 characterized via Rutherford backscattering spectrometry (RBS), allows for the substrate to adopt the topography of the HPMC film and its hydrophilic properties. The HPMC surface composition maintains a bulk stoichiometric ratio as confirmed by 4.265 MeV 12C(α, α)12C and 3.045 MeV 16O(α, α)16O, and 2.8 MeV He++ elastic recoil detection (ERD) of hydrogen. Both PIXE and RBS methods give comparable areal density results of polymer films on Si(100), silica, and PDMS silicone substrates. The SFE and topography of PDMS silicone polymers used for IOLs can also be modified by IBMM. IBMM of HPMC cellulose occurs during IBA as well. Damage curves and ERD are shown to characterize surface desorption accurately during IBMM so that ion beam damage can be accounted for during analysis of polymer areal density and composition. IBMM of Si(100)-SiO2 ordered interfaces also induces changes of SFE, as ions disorder surface atoms. The SFE converges for all surfaces, hydrophobic and hydrophilic, as ions alter electrochemical properties of the surface via atomic and electronic displacements.
ContributorsXing, Qian (Author) / Herbots, Nicole (Thesis advisor) / Culbertson, Robert (Thesis advisor) / Chamberlin, Ralph (Committee member) / Treacy, Michael (Committee member) / Smith, David (Committee member) / Arizona State University (Publisher)
Created2011
Description
Semiconductor wafers are analyzed and their total surface energy γT is measured in three components according to the van Oss theory: (1) γLW, surface energy due to Lifshitz-van der Waals forces or dipole interactions, (2) γ+, surface energy due to interactions with electron donors, and (3) γ–, surface energy due to interactions with electron acceptors. Surface energy is measured via Three Liquid Contact Angle Analysis (3LCAA), a method of contact angle measurement using the sessile drop technique and three liquids: water, glycerin, and α-bromonaphthalene. This research optimizes the experimental methods of 3LCAA, proving that the technique produces reproducible measurements for surface energy on a variety of surfaces. Wafer surfaces are prepared via thermal oxidation, rapid thermal oxidation, ion beam oxidation, rapid thermal annealing, hydrofluoric acid etching, the RCA clean, the Herbots-Atluri (H-A) process, and the dry and wet anneals used for Dry and Wet NanoBonding™, respectively.
NanoBonding™ is a process for growing molecular bonds between semiconducting surfaces to create a hermetic seal. NanoBonding™ prevents fluid percolation, protecting integrated electronic sensors from corrosive mobile ion species such as sodium. This can extend the lifetime of marine sensors and glucose sensors from less than one week to over two years, dramatically reducing costs and improving quality of life for diabetic patients. Surface energy measurement is critical to understanding and optimizing NanoBonding™. Surface energies are modified through variations on the H-A process, and measured via 3LCAA. The majority of this research focuses on silicon oxide surfaces.
This is the first quantitative measurement of gallium arsenide surface energy in three components. GaAs is a III-V semiconductor with potential commercial use in transistors, but its oxide layer slowly evaporates over time. In subsequent research, 3LCAA may prove key to developing a stable GaAs oxide layer.
NanoBonding™ is a process for growing molecular bonds between semiconducting surfaces to create a hermetic seal. NanoBonding™ prevents fluid percolation, protecting integrated electronic sensors from corrosive mobile ion species such as sodium. This can extend the lifetime of marine sensors and glucose sensors from less than one week to over two years, dramatically reducing costs and improving quality of life for diabetic patients. Surface energy measurement is critical to understanding and optimizing NanoBonding™. Surface energies are modified through variations on the H-A process, and measured via 3LCAA. The majority of this research focuses on silicon oxide surfaces.
This is the first quantitative measurement of gallium arsenide surface energy in three components. GaAs is a III-V semiconductor with potential commercial use in transistors, but its oxide layer slowly evaporates over time. In subsequent research, 3LCAA may prove key to developing a stable GaAs oxide layer.
ContributorsDavis, Ender (Author) / Herbots, Nicole (Thesis director) / Culbertson, Robert (Committee member) / Watson, Clarizza (Committee member) / Barrett, The Honors College (Contributor)
Created2016-05