研究目的
Investigating the influence of BSFCO thickness on the microstructure, dielectric relaxation, ferroelectric properties and resistive switching (RS) of the thin films.
研究成果
The BSFCO/CFO thin films with different thicknesses of the BSFCO layer were prepared by CSD method. The BSFCO and CFO phases exhibit structural distortion owing to existing strain in the prepared thin films, but they still retain their trigonal R3c: H and Cubic Fd-3m structures, respectively. The variable BSFCO thickness has an impact on the dielectric relaxation, ferroelectric polarization and the RS behavior. The dielectric relaxation has been observed in the bilayer thin films and studied according to the Maxwell-Wagner two-layer model by dielectric spectroscopy and AC impedance measurements. The observed decreases in relaxation time and dielectric loss peaks with the decreasing strain, are closely related to the interfacial polarization taking place between the BSFCO and CFO layer. The leakage current decreases and the ferroelectric properties improve with decreasing the strain in the thin films, with the 12-BSFCO/CFO thin film exhibiting a large Pr~102.9 μC/cm2 at 660 kV/cm. The RS behavior is observed in the BSFCO/CFO heterostructure, and the interfacial conduction mechanism plays a dominant role in this behavior. The switching of the different resistance states occurs with variations in the depletion region width and potential barrier height that affected by the ferroelectric polarization switching.
研究不足
The study focuses on the effects of BSFCO thickness on the properties of the thin films, but does not explore the effects of other variables such as temperature or different materials.
1：Experimental Design and Method Selection:
The BSFCO and BSFCO/CFO thin films were prepared on fluorine-doped tin oxide (FTO)/glass substrates by a chemical solution deposition method (CSD). The CFO precursor solution was spin-coated onto the substrates, dried at 200°C for 8 min, and annealed at 600°C for 30 min. This procedure was repeated seven times to obtain CFO films with the desired thickness. The BSFCO precursor solution was then spin-coated on top of the CFO layer, after which the wet films were preheated at 200°C for 8 min and then annealed at 540°C for 10 min. This procedure was repeated three, six, nine, or twelve times to obtain BSFCO/CFO layered thin films of various thicknesses (denoted by 3-, 6-, 9-, and 12-BSFCO/CFO). To investigate the electrical properties of the films, an Au electrode with an area of
2：502 mm2 was sputtered onto the surface of the layered thin films using a shadow mask. A capacitor was then obtained after annealing at 300°C for 20 min. Sample Selection and Data Sources:
The samples were characterized using a D/max-2200 X-ray diffractometer, a field emission scanning electron microscope (Hitachi S4800), an Agilent E4980A precision LCR meter, an Agilent B2901A source/measure unit, an electrochemical workstation (CHI660E), X-ray photoelectron spectroscopy (XPS), and a Radiant Ferroelectric Analyzer.
3：List of Experimental Equipment and Materials:
D/max-2200 X-ray diffractometer, Hitachi S4800 field emission scanning electron microscope, Agilent E4980A precision LCR meter, Agilent B2901A source/measure unit, CHI660E electrochemical workstation, X-ray photoelectron spectroscopy (XPS), Radiant Ferroelectric Analyzer.
4：Experimental Procedures and Operational Workflow:
The films were prepared by CSD method, characterized for microstructure, dielectric properties, leakage currents, and ferroelectric properties.
5：Data Analysis Methods:
The Maxwell-Wagner two-layer model was used to analyze the dielectric relaxation, and the relaxation time τ was calculated.
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