Impact of Template Layers on Dielectric and Electrical Properties of Pulsed-Laser Ablated Pb(Mg_(1/3) Nb_(2/3))O_3 - PbTiO_3 Thin Films

摘要

A study was done on pulsed laser deposited relaxor ferroelectric thin films of 0.7Pb(Mg_(1/3)Nb_(2/3))O_3-0.3PbTiO_3 (PMN-PT) deposited on platinized silicon substrates with template layers to observe the influence of the template layers on physical and electrical properties. Initial results, showed that perovskite phase (80% by volume) was obtained through proper selection of the processing conditions on Pt/Ti/SiO_2/Si substrates. The films were grown at 300℃ and then annealed in a rapid thermal annealing furnace in the temperature range of 750-850℃ to induce crystallization. Comparison of the films annealed at different temperatures revealed a change in crystallinity, perovskite phase formation and grain size. These results were further used to improve the quality of the perovskite PMN-PT phase by inserting thin layers of TiO_2 on the Pt substrate. These resulted in an increase in perovskite phase in the films even at lower annealing temperatures. Dielectric studies on the PMN-PT films show very high values of dielectric constant (1300) at room temperature, which further improved with the insertion of the template seed layer. The relaxor properties of the PMN-PT were correlated with Vogel-Fulcher theory to determine the actual nature of the relaxation process.