Ultrafast switching in wetting properties of TiO{sub 2}/YSZ/Si(001) epitaxial heterostructures induced by laser irradiation

Journal Article · Thu Feb 14 00:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4790327· OSTI ID:22102268

Bayati, M. R.; Molaei, R.; Narayan, J. ^[1]; Joshi, S. ^[2]; Narayan, R. J. ^[1]

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1. Department of Materials Science and Engineering, North Carolina State University, EB-1, Raleigh, North Carolina 27695-7907 (United States)
2. Amity Institute of Nanotechnology, Noida, Uttar Pradesh 201301 (India)

We have demonstrated dark hydrophilicity of single crystalline rutile TiO{sub 2}(100) thin films, in which rapid switching from a hydrophobic to a hydrophilic surface was achieved using nanosecond excimer laser irradiation. The TiO{sub 2}/YSZ/Si(001) single crystalline heterostructures were grown by pulsed laser deposition and were subsequently irradiated by a single pulse of a KrF excimer laser at several energies. The wettability of water on the surfaces of the samples was evaluated. The samples were hydrophobic prior to laser annealing and turned hydrophilic after laser annealing. Superhydrophilic surfaces were obtained at higher laser energy densities (e.g., 0.32 J.cm{sup -2}). The stoichiometries of the surface regions of the samples before and after laser annealing were examined using XPS. The results revealed the formation of oxygen vacancies on the surface, which are surmised to be responsible for the observed superhydrophilic behavior. According to the AFM images, surface smoothening was greater in films that were annealed at higher laser energy densities. The samples exhibited hydrophobic behavior after being placed in ambient atmosphere. The origin of laser induced wetting behavior was qualitatively understood to stem from an increase of point defects near the surface, which lowered the film/water interfacial energy. This type of rapid hydrophobic/hydrophilic switching may be used to facilitate fabrication of electronic and photonic devices with novel properties.

• OSTI ID: 22102268
• Journal Information: Journal of Applied Physics, Vol. 113, Issue 6; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
ATOMIC FORCE MICROSCOPY
ENERGY BEAM DEPOSITION
EPITAXY
EXCIMER LASERS
KRYPTON FLUORIDE LASERS
LASER RADIATION
LAYERS
MONOCRYSTALS
PULSED IRRADIATION
SEMICONDUCTOR MATERIALS
STOICHIOMETRY
SURFACE ENERGY
THIN FILMS
TITANIUM OXIDES
VACANCIES
X-RAY PHOTOELECTRON SPECTROSCOPY
YTTRIUM OXIDES
ZIRCONIUM OXIDES