Wafer-level growth of p4 mm -textured BaTiO3 films on SiO2-on-Si substrates by RF magnetron sputtering

Integrating barium titanate (BTO) films on SiO2/Si-based platforms is essential for the development of future nanophotonic modulators in photonic integrated circuits (PIC). However, the integration of BTO films on these amorphous platforms is far from trivial. In this work, the direct growth of tetragonal crystal (p4 mm)-textured BTO films on 4-in. SiO2/Si using a magnesium oxide (MgO) buffer layer by a magnetron sputtering process is developed. This work presents a systematic study on the evolution of crystallographic orientation and anisotropy energy in BTO films as a function of film thickness. Furthermore, a detailed analysis is conducted on the growth kinetics of BTO films, with the thickness-dependent evolution of surface morphology and Ba/Ti. Simultaneously, strain-engineered BTO films with a Curie temperature (Tc > 360 °C) are demonstrated. This integration method overcomes the lattice matching limitation between BTO and the amorphous substrate, offering a low-cost, flexible integration approach for next-generation PIC platforms.