Fabrication of highly homogeneous Al-doped TiO2 nanotubes by nanolamination of atomic layer deposition

Conformal parallel arrays of Al-doped TiO2 nanotubes were fabricated by atomic layer deposition. TiO2/Al2O3 bilayered shells were grown on a polycarbonate template by various cyclic sequences of TiO2 and Al2O3. The doping level of Al could be tuned by the fraction of cycle number of Al2O3. From the depth profiles measured by second ion mass spectrometry, Al is uniformly distributed across the thickness, which is also supported by the analyses of X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. A uniform bulk solubility of similar to 7 at.% and the surface concentration of similar to 18 at.% were observed with the cycle ratio of Al2O3: TiO2 at 0.04.