Effect of Deposition Parameters on the Microstructural Evolution and Electrical Properties of Charge-Balanced Barium Strontium Titanate Ferroelectric Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition

摘要

Barium strontium titanate (Ba_(0.60)Sr_(0.40)TiO_3) thin films are the main materials of interest in tunable phase shifter for microwave antenna applications. Ba_(0.60)Sr_(0.40)Y_(0.05)Ta_(0.90)Ti_(0.90)O_3 thin films, of nominal thickness ranging from 1.7 μm to 2.3 μm, were synthesized on MgO (100) substrates, at substrate temperatures ranging from 500°C to 900°C, at oxygen partial pressures 20 and 50 mTorr, at 500 mJ energy fluence on 3 mm x 1 mm spot size and 10 pulses per second using the pulsed laser deposition technique. All film synthesized at temperatures greater than 500°C were crystalline. The effect of the ionic substitution and substrate temperature in conjunction with the effect of the oxygen partial pressure on the microstructure, and mechanical and electrical properties of the thin films have been studied using shallow angle x-ray diffraction, SEM, nanoindentation, atomic force microscopy (AFM), and focused ion beam analysis (FIB) and are reported in detail. We are currently in the process of measuring the capacitance of these films by various methods.