Thickness dependent dielectric property of BaTiO3/SrTiO3 artificial lattice

Abstract

BaTiO3 (BTO)/SrTiO3 (STO) artificial lattices have been fabricated on (La,Sr)CoO3-coated MgO(100) single crystal substrate by pulsed laser deposition (PLD). Specifically, the artificial lattice with a stacking period of two-unit-cell-thick BTO and STO layers (BTO2/STO2) was investigated for the thickness-dependent dielectric property in the range of thickness from 100 nm to 10 nm. The structural analysis of the artificial lattice was carried out by synchrotron X-ray scattering. In the BTO2/STO2 artificial lattice with various thickness, the strained BTO and STO layers maintained the lattice coherence. The BTO layer in the artificial lattice was in a biaxial compressive stress, while the STO layer was in a biaxial tensile stress. As the thickness of the artificial lattice decreased, the BTO lattice became severely distorted while the lattice distortion of the STO lattice remained relatively unchanged. The corresponding dielectric constant of the artificial lattice decreased with decreasing thickness of the artificial lattice, although the dielectric constant of the artificial lattice was larger than other single layers such as STO, BTO, and BST layers with the same thickness. The finite-size effect was still observed in the artificial lattice with thickness down to 10nm.