Structural control and combinatorial doping of titanium dioxide thin films by laser molecular beam epitaxy

Structural control of titanium dioxide, TiO2, thin films was achieved by the selection of appropriate substrates. The rutile phase of the TiO2 thin film was grown on α-Al2O3(0 0 0 1) substrate, while the anatase phase was on SrTiO3(0 0 1) and LaAlO3(0 0 1) substrates. The crystallinity of the anatase films has been much improved by the use of the LaAlO3(0 0 1) substrate. The combinatorial doping with 3d transition metals in the TiO2 thin films was carried out for the rutile and anatase films in much shorter time than the conventional one-by-one process, leading to the discovery of transparent ferromagnetism in the Co-doped anatase film.