Properties and thermal stability of solution processed ultrathin,high-k bismuth titanate (Bi2Ti2O7) films |
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| Authors: | A Hardy S Van Elshocht C De Dobbelaere J Hadermann G Pourtois S De Gendt VV Afanas’ev MK Van Bael |
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| Affiliation: | 1. Energy Materials Convergence Research Department, Korea Institute of Energy Research, 71-2, Jang-dong, Yuseong-gu, Daejeon 305-343, Republic of Korea;2. Jeju Global Research Center, Korea Institute of Energy Research, 200, Haemajihaean-ro, Gujwa-eup, Jeju Special Self-Governing Province 695-971, Republic of Korea;1. Material Science and Metallurgical Engineering Department & Center for Research in Nanoengineering, UniversistatPolitècnica de Catalunya, Avda. Diagonal 647 (ETSEIB), 08028 Barcelona, Spain;2. Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Américo Vespucio 49, 41092 Sevilla, Spain |
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| Abstract: | Ultrathin bismuth titanate films (Bi2Ti2O7, 5–25 nm) are deposited onto SiO2/Si substrates by aqueous chemical solution deposition and their evolution during annealing is studied. The films crystallize into a preferentially oriented, pure pyrochlore phase between 500 and 700 °C, depending on the film thickness and the total thermal budget. Crystallization causes a strong increase of surface roughness compared to amorphous films. An increase of the interfacial layer thickness is observed after anneal at 600 °C, together with intermixing of bismuth with the substrate as shown by TEM-EDX. The band gap was determined to be ～3 eV from photoconductivity measurements and high dielectric constants between 30 and 130 were determined from capacitance voltage measurements, depending on the processing conditions. |
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