Growth of ferroelectric oxide films on n-GaN/c-sapphire structures

High-quality (Pb, La)(Ti, Zr)O3 films were grown on n-GaN. The film thickness ranged from 0.5 to 5 μm. The material was prepared by a chemical solution method with compositions of 8/65/35 and 0/52/48. The films grown on GaN buffered with a thin layer of indium in oxide were highly textured and exhibited excellent ferroelectric properties with Pr=20–26 μC/cm2. A large field-induced birefringence of 0.025 was measured in the film with a composition of 8/65/35 under a field strength of 2×105 V/cm.