Effects of periodicity and oxygen partial pressure on the crystallinity and dielectric property of artificial SrTiO 3/BaTiO 3 superlattices integrated on Si substrates by pulsed laser deposition method

Abstract

Epitaxial SrTiO 3(STO)/BaTiO 3(BTO) artificial superlattices have been grown on TiN buffered Si (001) substrates by pulsed laser deposition method and the effects of stacking periodicity and processing oxygen partial pressure on their crystallinity and dielectric properties were studied. The crystal orientation, epitaxy nature, and microstructure of STO/BTO superlattices were investigated using X-ray diffraction and transmission electron microscopy. The TiN buffer layer and superlattice thin films were grown with cube-on-cube epitaxial orientation relationship of [110](001) films∣∣[110](001) TiN∣∣[110](001) Si. The c-axis lattice parameter of the STO/BTO superlattice decreased from 0.412 nm to 0.406 nm with increasing oxygen partial pressure and the dielectric constants, measured at the frequency of 100 kHz at room temperature, of the superlattices with 2 nm/2 nm periodicity increased from 312 at 1 × 10 − 5 Torr to 596 at 1 × 10 − 3 Torr. The dielectric constants of superlattices grown at oxygen partial pressure of 1 × 10 − 3 Torr increased from 264 to 678 with decreasing periodicity of the superlattices from 10 nm/10 nm to 1 nm/1 nm.