Crystallization of Sub-100 nm-Thick Bi4-xLaxTi3O12 Films on Silicon Substrates and Their Electrical Properties

Abstract

ABSTRACTPolycrystalline Bi4-xLaxTi3O12 (BLT) thin films were formed on p-Si(100) substrates. Crystallization of the film was investigated quantitatively by X-ray diffraction (XRD) and X-ray reflection (XRR) analyses. The film was crystallized onto bismuth-oxide layered perovskite structure when annealing temperatures became higher than 550°C. The annealing time dependence of diffraction intensity and peak width indicated that grain growth occurred during crystallization. Moreover, it was shown that the average crystal dimension in the BLT film reached ca. 60 nm by 120-min annealing. That value is comparable to the B LT thickness. Film thickness and density were evaluated by XRR analysis. Simulation fitting showed that the BLT film was densified and that an interfacial layer was formed during crystallization. Pole figure measurements also suggested that the c-axis of B LT was preferentially oriented to nearly parallel the surface. Clockwise hysteresis loops were observed at room temperature in capacitance-voltage (C-V) characteristics of Au/BLT/p-Si structures. The coercive field and the dielectric constant of 65 nm-thick BLT films crystallized at 550°C for 60 min were evaluated to be ca. 23 kV/cm and ca. 17, respectively.