Enhanced a-axis-oriented crystal growth of Nd-substituted bismuth titanate thin films with layer-by-layer crystallization

摘要

Nd-substituted bismuth titanate (Bi_(3.5)Nd_(0.5)Ti_3O_(12), BNdT) films were prepared on Pt electrodes using chemical solution deposition. Enhanced a-axis-oriented crystal growth occurred when the crystallization was performed on every spin-coated layer with sufficiently thin thickness (～20nm). The remnant polarization (2P_r ～ 38 μC/cm~2) of the film derived by such a layer-by-layer crystallization method was significantly higher than that of the film derived with the conventional process (2P_r ～ 10 μC/cm~2). Examination of structural evolution has indicated that, owing to the geometrical effect, the growth of (11 7)-oriented crystals was restricted by the layer thickness, while the growth of a-axis-oriented crystals was not. As a result, BNdT films prepared by layer-by-layer crystallization are dominated by a-axis-oriented crystals and show high remnant polarization.