Electric-Field-Induced Domain Switching And Pinning State In Lead-Free Ferroelectric Bst 80/20 Film

Ferroelectric nanodomains were created in Ba0.8Sr0.2TiO3 (BST 80/20) thin films by applying a voltage to a sharp conducting tip of a scanning probe microscope (SPM). The ferroelectric layer were grown on (100)-oriented silicon substrate by radio frequency magnetron sputtering. The surface of the sample shows small grains which diameter ranges from 50 nm to 75 nm and roughness is less than 5 nm. Using the piezoresponse mode of the SPM to detect the out-of-plane film polarization, the domain sizes were measured as a function of the applied writing voltage and the pulse time. It was found that the time dependence of the domain diameter in a 400 nm thick BST 80/20 film well described by logarithmic law observed earlier in Pb(Zr0.2Ti0.8)O-3 (PZT) films The dynamics of domain growth is analyzed theoretically taking into account the strong inhomogeneity of the external electric field in the film and the influence of the bottom electrode. Therefore, the BTS film with good polarization switching properties could act as a memory element in nonvolatile ferroelectric random access memory (NV-FRAM) devices.