title: Enabling high solubility of ZnO in TiO₂ by nanolamination of atomic layer deposition.
abstract: Zn-doped TiO2 nanotubes were fabricated by nanolaminated packing of alternating layers of TiO2 and ZnO by atomic layer deposition (ALD) using a polycarbonate (PC) membrane as a template. With 400 cycles of ALD, the nanotubes with a thickness of 28 nm and an outer diameter of 220 nm were obtained after removing the PC membrane by annealing at 450 °C. The doping concentration of ZnO in TiO2 depends on the precursor cycle ratio of ZnO to TiO2. With the precursor cycle ratio of ZnO : TiO2 at 0.04, a uniform bulk solubility of ∼8 at% is obtained, and the surface concentration of Zn is even higher, ∼16 at%. From the depth profiles measured by secondary ion mass spectrometry, Zn is uniformly distributed across the thickness, which is further confirmed by analyses of X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. Additionally, from the transmission electron microscopic observation, the highly doped anatase TiO2 exhibits some regions of severe deformation that results in localized solid-state amorphization.
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University 101 Section 2, Kuang-Fu Rd, Hsinchu 300, Taiwan. tpperng@mx.nthu.edu.tw.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Su
authors.forename: C-C
authors.initials: CC
authors.lastname: Wang
authors.forename: Y-C
authors.initials: YC
authors.lastname: Hsueh
authors.forename: V
authors.initials: V
authors.lastname: Gurylev
authors.forename: C-C
authors.initials: CC
authors.lastname: Kei
authors.forename: T-P
authors.initials: TP
authors.lastname: Perng