Investigation of the physical, optical, and chemical properties of phase segregated AlCoOx thin films from a novel hexol-type cluster

Abstract

The use of a novel inorganic nanoscale cluster (Al[(μ-OH)₂Co(NH₃)₄]₃(NO₃)₆) was investigated for its utility as a precursor for AlCoOx films. Mixed-metal aluminum and cobalt oxide thin films were solution deposited from the novel cluster solution via the spin-coating method on Si (100) and quartz substrates. The films were annealed at increasing temperatures up to 800 °C, and characterization of these films via TEM and XRD confirms binary Co₃O₄ crystalline phase present in an amorphous Al₂O₃ network. Films are relatively smooth (R_rms < 4 nm), polycrystalline, and demonstrate a tunable optical response dominated by Co₃O₄ with two electronic transitions.