The structure and electrical properties of multi-ion beam reactive sputter (MIBERS) deposited barium strontium titanate (BST) films were characterized in terms of Ba/Sr ratio, substrate temperature, annealing temperature and time, film thickness, doping concentration, and secondary low-energy oxygen ion bombardment. Films deposited onto unheated substrates, followed by annealing at 700 °C showed lower dielectric constant (<200), compared to a dielectric constant of about 560 for those deposited at elevated temperatures, probably due to reduced voids. Two types of microstructures (type I and type II) were observed depending on the incipient phase of the as-grown films, which also led to two types of time domain dielectric response, Curie-von Schweidler and Debye type, respectively. The current-voltage (I-V) characteristics of type II films doped with high donor concentration showed a bulk space-charge-limited conduction (SCLC) with discrete shallow traps embedded in a trap-distributed background at high electric fields. The I-V characteristics of bombarded films deposited at higher substrate temperatures showed promising results of lower leakage currents and trap densities.
Effect of thermal annealing on the morphology of sol–gel processed barium strontium titanate thin films: Consequences on electrical properties