A Combinatorial Sputtering Approach to Properties Modification in Polaron Conducting Films
EMSL Project ID
2525
Abstract
The influence of sputtering parameters and cation composition on measured resistivity and optical transparency of mixed transition metal spinel oxides (AB2O4) will be systematically studied. A two-cathode system will be used to deposit films having continuously variable compositions onto glass, silicon, and sapphire substrates (25 mm in length) as a function of process gas composition and pressure, target to substrate distance, substrate temperature, sputtering power, and sputtering time. The intent is to correlate transparency and conductivity with composition, phase purity, grain size, film thickness, and cation oxidation state. Both mixed metal oxide and metal alloy targets (nickel, cobalt, rhodium, palladium) will be used for sputter deposition with variable gas mixtures of argon and oxygen. Preliminary findings show that post deposition annealing of sputtered films was found to lower film resistivity but have little effect on optical transparency. Film resistivity returned to its original value upon standing in air for two weeks. However, partial substitution of lithium for cobalt was found to not only improve the conductivity and increase transparency but also to stabilize these properties when subjected to post deposition annealing in air. Results suggest that the presence of lithium stabilizes higher oxidation states of the resident transition metal cations leading to lattice compression and diminished oxygen transport.Synthesis will require RF sputter Deposition. Analytical capabilities will require XRD, XPS, AFM/STM, SIMS, and optical characterization
Project Details
Project type
Exploratory Research
Start Date
2002-05-29
End Date
2004-02-19
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Owings RR, PH Holloway, GJ Exarhos, and CF Windisch, JR. 2004. "The effect of annealing and lithium substitution on conductivity in nickel cobalt oxide spinel films." Presented by Robert Owings at 26th Annual Sumposium on Applied Surface Analysis, Richland, WA on June 18, 2004. PNNL-SA-41822.