Ferroelectric and Optical Properties of BST/BZT/BST Sandwich Structure Thin Films Prepared by RF Sputtering

摘要

In this work, (Ba_(0.65)Sr_(0.35))TiO_3 (BST) and Ba(Zr_(0.20)Ti_(0.80))O_3 (BZT) ceramic targets were prepared using the traditional solid-state reaction technique, which were sintered at 1200°C for 2 h. The thin films of BST, BZT and sandwich structure BST/BZT/BST were grown on Pt/Ti/SiO_2/Si(100) and Si(100) substrates by rf-sputtering at 500°C, respectively. And all samples crystallied at temperatures 650°C for 30 min in oxygen atmosphere. The cross-sectional images of the thin films were characterized by scanning electron microscope (SEM). The dielectric constant and dissipation factor tanδ of the BZT, BST and BST/BZT/BST thin films are 680 and 0.030, 240 and 0.021, 85 and 0.018, respectively at 100 kHz. Compared with BST and BZT films, the BST/BZT/BST film has lower dielectric constant and lower dissipation. The remanent polarization (P_r) of the sandwich structure BST/BZT/BST thin film is up to 9.57 μC/cm~2, the P_r value is larger than that BST (0.25μC/cm~2) film and BZT (8.45μC/cm~2) film. The optical properties (refractive index n and extinction coefficient k) of the BST/BZT/BST film on Si(100) substrate were measured by n & k analyzer 2000.