Nanotribological properties of ALD-processed bilayer TiO2/ZnO films.

TiO 2 /ZnO films grown by atomic layer deposition (ALD) demonstrated nanotribological behaviors using scratch testing. TEM profiles obtained an amorphous structure TiO 2 and nanocrystalline structure ZnO, whereas the sample has significant interface between the TiO 2 /ZnO films. The experimental results show the relative XRD peak intensities are mainly contributed by a wurtzite oxide ZnO structure and no signal from the amorphous TiO 2 . With respect to tribology, increased friction causes plastic deformation between the TiO 2 and ZnO films, in addition to delamination and particle loosening. The plastic deformation caused by adhesion and/or cohesion failure is reflected in the nanoscratch traces. The pile-up events at a loading penetration of 30 nm were measured at 21.8 μN for RT, 22.4 μN for 300 °C, and 36 μN for 400 °C. In comparison to the other conditions, the TiO 2 /ZnO films annealed at 400 °C exhibited higher scratch resistance and friction with large debris, indicating the wear volume is reduced with increased annealing temperature and loading. [ABSTRACT FROM AUTHOR]