Surface Morphology Study of Co-doped Anatase Films Grown on Various Substrates by OPA-MBE
Abstract
Co-doped anatase TiO_2, an optically transparent semiconducting material that is ferromagnetic at room temperature, is a promising candidate for spintronic devices. Oxygen-plasma assisted molecular beam epitaxy was used to grow Co_xTi_1-xO2 anatase TiO2 on four substrates with differing lattice matches to study the morphology of the film growth. The objective was to produce atomically flat films for use in spin injection devices. The four substrates studied were: Strontium Titanate (001), Silicon (001), Lanthanum Aluminate (001), and an Anatase (001) mineral sample. The crystallinity of the films was monitored in-situ during growth by Reflection High Energy Electron Diffraction, and after by Low Energy Electron Diffraction. The crystallinity of the films depends on the substrate, with the closest lattice matches having the highest crystalline order. All of the substrates showed the film to grow as anatase TiO2 with the cobalt always having a +2 oxidation state, as verified by high resolution X-ray Photoelectron Spectroscopy. The film morphology, as studied by Atomic Force Microscopy, differed greatly depending on the growth conditions and the substrate-film lattice mismatch. The ferromagnetic properties depend on the film growth parameters and not directly on the substrate or morphology of the films.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARM19011R