Thin film fabrication using nanoscale flat substrates

Abstract Recently, there has been a great deal of interest in nanosized ferroelectric materials because of the need to produce energy harvesting devices with higher reliability. Since the characteristics of these devices are affected by the dielectric behavior in nanoscale regions, it is important to produce nanocrystals that are highly uniform both in terms of size and quality. Nanocrystals have been prepared using bottom-up methods, such as initial growth nucleation; however, it is difficult to control the nucleation positions and the final crystal size using these methods. In this study, lead titanate (PbTiO 3 ) and platinum (Pt) nanocrystals were prepared on atomically flat sapphire substrates at a very low deposition rate in order to achieve position and size control. Atomically flat sapphire (0001) substrates were prepared by annealing at 1000°C. The substrates had a step-terrace structure with a step height of 0.22 nm. A shielding plate for reducing the deposition rate was placed in front of the substrate during the sputtering process. Nanocrystals with a uniform size were successfully grown on the surface step edges, demonstrating that it is possible to fabricate well-ordered nanocrystal arrays using this shielding technique. The crystals were evaluated by X-ray photoelectron and Raman spectroscopy, and the results revealed that well-ordered Pt and perovskite PbTiO 3 nanocrystals were produced. Therefore by optimizing the deposition conditions, it is possible to control both the nanocrystal nucleation sites and the crystal size and quality using a bottom-up method. This opens the possibility for complete coverage of a substrate with nanoscale single crystals with a uniform size.