Study on microstructure and ferroelectric properties of Gd doped PZT thin films

The Pb(Zr_0.52Ti_0.48)O₃ thin films with Gd dopants (denoted as PGZT) were prepared on Pt/Ti/SiO₂/Si substrates by a sol-gel technique and a rapid thermal annealing (RTA) process. Effects of pyrolyzing temperature on the phase formation of preferential orientation in PGZT films were investigated. It was shown that pyrolyzing at 450°C and RTA at 650°C are the favorable processing for the formation of PGZT thin films with (100) orientation. Surface morphologies and roughness of PZT thin films with different Gd content were analyzed by SEM and FAM. The ferroelectric properties of PGZT thin films deposited on Pt bottom electrode (Pt/Gd-PZT/Pt) were investigated. Improved ferroelectric properties were obtained in PZT films with 1mol% Gd doing. The remanent polarization of 1mol% Gd-PZT was 46.373μC/cm² and decreased by 45% after 10¹⁰ switch cycles. With the Gd doping level increased to 2mol%, a decreased remanent polarization was fund. It was inferred that when the Gd doping content is less than 1mol%, Gd is mainly occupied A-site in PZT lattice and acts as donor dopant. With the Gd doping level increased to more than 1mol%, the content of B-site occupancies is increased and acceptor doping is to be dominant.