Conformal Growth of Textured Barium Titanate Films on Patterned Silicon Wafer

This work presents a fabrication process for the conformal growth of vertically aligned BaTiO₃ films on 3-dimensionally patterned silicon waters. The conformal growth is performed through a two-step hydrothermal reaction that enables the direct growth of piezoelectric films on nonplanar architectures while utilizing relatively low synthesis temperatures. Scanning electron microscopy (SEM) is used to show the controllable conversion of TiO₂ nanowires to BaTiO₃ films and x-ray diffraction (XRD) is used to validate the crystal structures. Tested by a refined piezoresponse force microscopy (PFM) method, the conformal films exhibited a piezoelectric coupling coefficient as high as 100 pm/V. With superior piezoelectric properties and the capability to grow on design specific surfaces, the BaTiO₃ conformal films demonstrate high potential for sensors, random access memory, and other micro-electromechanical systems.