Enhancement of piezoelectric response in Ga doped BiFeO3 epitaxial thin films

The piezoelectric properties of compositional spread (1 − x)BiFeO3-xGaFeO3 epitaxial thin films are investigated where Ga3+ substitution for Bi3+ is attempted in Bi1−xGaxFeO3 compounds. Ga content x was varied from 0 to 12% (atomic). Ferroelectric characterizations are reported at various length scales. Around 6.5% of Ga content, an enhancement of the effective piezoelectric coefficient d33eff is observed together with a change of symmetry of the film. Measured d33eff values in 135 nm thick films increased from 25 pm/V for undoped BiFeO3 to 55 pm/V for 6.5% Ga with no extrinsic contribution from ferroelastic domain rearrangement.