Fabrication of BaTiO/sub 3//SrTiO/sub 3/ artificial superlattice and its dielectric properties

Artificial superlattices of BaTiO₃/SrTiO₃ were fabricated on Nb-doped SrTiO₃ (001) substrates alternating evaporation method using a molecular epitaxy (MBE) apparatus. Streak patterns observed with an in-situ 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/(SrTiO ₃)₂₀]₂ superlattice, and C-V curves showed hysteresis characteristic probably due to polarization reversals