Electro-optic properties of sol-gel derived PZT and PLZT thin films

Ferroelectric(FE) films exhibit interesting electro-optic (EO) properties and are utilized in devices used for second harmonic generation, spatial light modulators and optical switches. These films typically yield large values of linear and quadratic electro-optic coefficients. Solgel derived FE films namely PZT 53 47 and PLZT 28/0/100 were prepared on conductive glass substrates. 0.5M precursor solutions based on the appropriate stoichiometric amounts of lead acetate, La nitrate and Ti Zr alkoxides were refluxed for 1 hour and later spincoated on the substrates. They were the fired to 600C to crystallize them into single phase perovskite films. Top Au Pd electrodes were deposited to form the top contacts for the capacitors. The refractive indices, extinction coefficients, linear and quadratic coefficients of the films were obtained using multiangle reflection ellipsometry. These parameters were then used to calculate the linear and quadratic electro-optic coefficients of the films. The quadratic EO coefficients of PLZT 28/0/100 and PZT 53 47 films were measured to be 0.07 and 0.38 × 10^-16 m²/V² respectively while the linear electrooptic coefficients of PLZT 28/0/100 and PZT 53 47 were found to be 59 and 315 pm/V respectively, with the r_eff value for PZT 53 47 the highest among reported ferroelectric films in literature.