Effect of La and Co-doping on microstructure and electrical properties of BiFeO3 thin films
2014
Wu, Jiagang | Xiao, Dingquan | Zhu, Jianguo
Adding both La³⁺and Co³⁺was used to tune the microstructure and electrical properties of BiFeO₃(BFO) thin films, and Bi₁₋ₓ La ₓ Fe₀.₉₀Co₀.₁₀O₃thin films were grown on the SrRuO₃-buffered Pt-coated silicon substrates by a radio frequency sputtering. A polycrystalline structure with (110) orientation was shown in thin films, and their resistivity dramatically increases as the La³⁺content increases. Their dielectric constant increases, and dielectric loss decreases with increasing La³⁺content. In addition, their ferroelectric and fatigue properties were enhanced with rising La³⁺content. The thin films with x = 0.03 have optimum electrical properties (e.g., remanent polarization 2Pᵣ ~ 175.6 μC/cm², coercive field 2Ec ~ 699.5 kV/mm, dielectric constant εᵣ ~ 257 and tan δ ~ 0.038), together with a good fatigue behavior. The impendence analysis of the films was conducted to identify the defects type during conductivity, and both hopping electrons and single-charged oxygen vacancies are mainly responsible for the conduction of grain and grain boundaries regardless of La³⁺content. As a result, the doping with both La³⁺and Co³⁺benefits the improvement in the electrical properties of BFO thin films.
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