| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1489107 | Materials Research Bulletin | 2012 | 7 Pages |
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.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Aqueous solution processed ultrathin Bi2Ti2O7 films below ∼20 nm thickness. ► Low temperature films are carbonate free, amorphous and have a high k value (33). ► High temperature allows crystallization and increases the k value (130). ► Crystallized films have higher roughness and thicker interfacial layers. ► Bismuth silicate is formed through interfacial reaction with the SiOx/Si substrate.
