Epitaxial growth of cobalt oxide by atomic layer deposition

Highly oriented thin films of cobalt oxide were made by the atomic layer deposition (ALD) technique, using Co(thd)(2) (Hthd = 2,2,6,6-tetramethylheptan-3,5-dione) and ozone as precursors. Films were deposited on single-crystalline substrates of MgO(1 0 0), alpha-Al2O3(0 0 1), and SrTiO3(1 0 0). Epitaxial growth has been established with the following orientations: (0 0 1)[1 0 0]Co3O4 parallel to(0 0 1)[1 0 0]MgO, (1 1 1)[1 1 1]Co3O4 parallel to(0 0 1)[0 0 1]alpha-Al2O3, and (0 0 1)[1 0 0]SrTiO3. The resulting texture was studied as function of deposition temperature in the range 138-283 degrees C for MgO(1 0 0) and 186-283 degrees C for the remaining substrates. The topography and morphology of the films were investigated by atomic force microscopy (AFM), and in selected cases scanning electron microscopy. The specific electronic resistivities of as-deposited films grown on the various substrates were measured to be from 0.8 to 85 Omega cm. (c) 2007 Elsevier B.V. All rights reserved.