Pyroelectricity of spontaneously poled La-modified lead titanate thin films on silicon based substrates

Multiple deposition by spin-coating and RTP crystallisation have been used to obtain La-modified lead titanate thin films of composition Pb0.88La0.08TiO3 (PTL) onto two types of substrates: Ti/Pt/Ti/(100)Si annealed at 650°C and Pt/TiO2/(100)Si. The films on Ti/Pt/Ti/(100)Si present a main <111> preferred crystallographic orientation, whereas the films on Pt/TiO2/(100)Si present a mixed <001>/<100> preferred orientation. All the films developed a net polarisation in the direction perpendicular to the film plane and a spontaneous pyroelectric coefficient. The hysteresis and switching characteristics of the films were dependent on the type of substrate. Results as a function of the number of deposited layers are presented. Poling was carried out under different electrical signals at 150°C. The highest pyroelectric coefficient achieved at room temperature was γ ∼40×10−9 C cm−2 K−1.