Integration of artificial SrTiO3/BaTiO3 superlattices on Si substrates using a TiN buffer layer by pulsed laser deposition method

Epitaxial SrTiO3(STO)/BaTiO3(BTO) artificial superlattices, STO, BTO, and (Ba0.5,Sr0.5)TiO3 (BSTO) thin films have been grown on TiN-buffered Si (0 0 1) substrates by pulsed laser deposition method and their dielectric properties were studied. The crystal orientation, epitaxy nature, and microstructure of epitaxial oxide thin films were investigated using X-ray diffraction and transmission electron microscopy. Thin films were prepared with laser fluence of 3 and 2 J/cm2, repetition rate of 8 and 10 Hz, substrate temperature of 700 and 650 °C for TiN and oxide, respectively. The TiN buffer layer and oxide thin films were grown with cube-on-cube epitaxial orientation relationship of [1 1 0](0 0 1)films∥[1 1 0](0 0 1)TiN∥[1 1 0](0 0 1)Si. The dielectric constants of BTO, STO, BSTO, and STO/BTO superlattice epitaxial thin films with 1 nm/1 nm periodicity were shown to be as high as 300, 410, 520, and 680 at the frequency of 100 kHz, respectively.