Friday, October 24, 2008 3:30 – 3:55 pm
Room 610, M&M Building
Department of Materials Science and Engineering
Michigan Technological University
Epitaxial (001)-oriented cerium dioxide (CeO2) thin film is an essential buffer layer forsubsequent integration of functional single-crystal cubic perovskite films on the commerciallyavailable large area r-plane sapphire (Al2O3) substrates. We report on how modifying the startingsubstrate morphology can lead to growth of epitaxial (001)CeO2 films on r-plane Al2O3substrates. Films grown on as received substrates were primarily of mixed (001) and (111)orientations. In general, low film growth rates and higher substrate temperatures, lead to ahigher volume fraction of (001)CeO2. The highest volume fraction of (001)CeO2 achieved in thecase of films grown on as received substrates, using the highest growth temperature andslowest growth rate of 830°C and 0.05nm/min respectively, was 81%. However when thesubstrates were annealed prior to film deposition, 100% (001)CeO2 films was obtained. Theemergence of a regularly spaced atomic step terrace features on the annealed wafer surface isbelieved to be key in enabling growth of epitaxial (001)CeO2 films. Crystallographic relationshipsbetween the atomic step edges and (001)CeO2 unit cells were derived, to understand the role ofpre-growth substrate annealing in promoting nucleation of (001)CeO2 on r-plane Al2O3substrates. (001)CeO2 films with atomic terraces and improved crystallinity were grown on pregrowth annealed r-plane Al2O3 substrates.