| Summary: | 博士 === 國立清華大學 === 材料科學工程學系 === 96 === Recently, Bismuth Ferrite (BiFeO3, BFO) thin films have been widely studied due to their large spontaneous polarizations. However, many issues need to be overcome by using BFO in FeRAM application. They include impurity phases, defects in crystallization, leakage currents, reliable properties, etc. In this dissertation, BFO thin films were fabricated by RF-magnetron sputtering method at low temperature (350˚C). To overcome the above mentioned issues, BFO was deposited not only on Pt bottom electrode, but also on (Ba0.5Sr0.5)TiO3 (BST) and BaPbO3 (BPO). Introducing BST and BPO as barrier layer between BFO and Pt indeed improve interface and electric characteristics.
The highly (110)- and (111)-oriented BFO thin films can be obtained on BPO/Ru and BPO/Pt/Ru stacks, respectively. Both highly oriented ferroelectric films have the potential for application in the 1T1C stack structures for high density FeRAM. The properties of BFO do not degrade after forming gas annealing treatment. In addition, replacing Pt top electrode by BPO can improve the fatigue property of BFO film. BFO can be a promising material for FeRAM application by utilizing BPO as electrode.
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