Dielectric property of lead titanate thin films prepared on glass substrate at low temperature

摘要

Lead based titanate (PbTiO3) is one of ferroelectric ceramic family that has been widely investigated of its dielectric property towards high capacitance passive device, i.e. capacitor. It has been known that high annealing temperature is needed to perform perfect crystal level of ferroelectric ceramic that is averagely 650°C done by using crystalline Si substrate with Pt/Ti as intermediate layer. This had been confirmed as the ideal process to have perfectly distribution of uniform grain size with tendency of stable dipole moment. However, high temperature does affect the nucleation site of domain wall where here lays the factor contributes to Pb volatilization and yields to thin films degradation. Further investigation of PbTiO3 thin films preparation at relatively lower temperature was at least 200°C could be the most desirable thin films ever to answer the limitation of source. Therefore, these temperatures make deposition of PbTiO3 possible for glass substrate which has low melting temperature. The current study investigates preparation of PbTiO3 thin films on platinum coated glass substrate through sol-gel spin coating method. The optimum thickness of thin films was achieved by five times of depositions and punctuated with drying process about 200°C for 10mins for each layer. Annealing process was carried out in hot furnace at temperature 300°C to 500°C for 30mins. The prepared thin films were then being measured by impedance analyzer under low frequency about 1000Hz for the dielectric property investigation. It was found that the dielectric constant have linear relationship with annealing temperature. Nevertheless, high dielectric constant resulted to the factor of high dielectric loss that plays a role as in AC signal. In addition, the capacitance value of PbTiO3 thin films is being obtained under low frequency of dielectric constant measurement. Concisely, both d- electric constant and nanometer scaled thin films had influenced much to the capability for high energy storage which will be discussed later in future investigation.