Control of epitaxial growth for SrBi2Ta2O9 thin films

We report the $\text{(a00)}$ oriented as well as the $\text{(00l)}$ oriented epitaxial ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ thin film grown on (100) ${\mathrm{LaAlO}}_3$ and (200) yttria-stabilized zirconia single crystal substrates. On (100) ${\mathrm{SrTiO}}_3$ single crystal substrate, we only observe the $\text{(00l)}$ oriented epitaxial growth of ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ thin film. We infer that the $\text{(a00)}$ oriented epitaxial growth results from the strain by the lattice mismatch. The band gaps of the $\text{(00l)}$ and the $\text{(a00)}$ oriented ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ films are $\text{∼3.9}$ and $\text{∼3.5}$ eV, respectively. The two epitaxial orientations of ferroelectric ${\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}}$ thin film can provide an opportunity to study the effects on microwave and optical waveguides as well as underlying anisotropic physical properties.