Fabrication of BaTiO3/SrTiO3 artificial superlattice and its dielectric properties

Artificial superlattices of BaTiO3/SrTiO3 were fabricated on Nb-doped SrTiO3 (001) substrates by an alternating evaporation method using a molecular beam epitaxy (MBE) apparatus. Streak patterns observed with an insitu reflection high-energy electron diffraction (RHEED) indicated that two-dimensional atomic layer epitaxy was achieved during the deposition. Artificial superlattices with the structure of [(BaTiO3)(m)/(SrTiO3)(m)](n), where (m, n)=(1, 40), (5, 8), (10, 4), (20, 2), (40, 1), were fabricated. X-ray diffraction analysis of satellite diffraction peaks indicated that the artificial superlattices had the designed structure. Dielectric permittivity of the artificial superlattices was measured as functions of frequency (C-f) and bias voltage (C-V). The C-f characteristic showed the dielectric relaxation, especially, in the structure of [(BaTiO3)(20)/(SrTiO3)(20)](2) superlattice, and C-V curves showed hysteresis characteristic probably due to polarization reversals.