Microstructure and crystallization of chemically derived PZT thin film using controlled solvent composition and rotational speed

Growth of thin film lead zirconate titanate (PZT) can be controlled via solvent composition and rotational speed. The objective of this research is to build a crack-free microstructure of PZT films and high crystallinity by modifying sols concentration in the sol-gel process and rotational speed in the spin coating process. The synthesis of PZT sols with the composition ratio of Pb/Zr/Ti: 100/50/50 near morphotropic phase boundary (MPB) was prepared with various sol concentrations by propanol addition of 1, 3, and 5 ml. The sols were deposited using spin coating technique onto silicon wafer substrate with rotational speeds of 2000 rpm, 3000 rpm and 4000 rpm, respectively. The microstructure of PZT films were characterized using XRD and SEM instruments. The XRD results show the intensities of the certain crystal orientation which indicate that the crystal size decreases with the increasing solvent composition and rotational speed. On the other hand, SEM images indicate that the increase in the rotational speed and less solvent addition provide the PZT films with better morphology including its fineness, flatness and homogenity. Furthermore, it was found that the number of cracks on the surface of PZT thin film could be minimized and even eliminated by adding small amount of solvent and increasing rotational speed. The percentage of tetragonal and rhombohedral phase is in the range of 33 % and 67 % respectively, indicating the chemical composition of PZT lies near MPB.