研究目的
To integrate epitaxial ferroelectric Hf0.5Zr0.5O2 capacitors on Si(001) substrates with high retention and endurance, and to investigate the role of bottom electrodes in stabilizing the ferroelectric phase.
研究成果
Epitaxial ferroelectric Hf0.5Zr0.5O2 capacitors were successfully integrated on Si(001) with high remnant polarization (~20 μC/cm2), retention exceeding 10 years at 5 MV/cm, and endurance up to 109 cycles at 4 MV/cm. The LSMO bottom electrode is critical for stabilizing the ferroelectric phase. This achievement facilitates the development of homogeneous nanoscale devices and deeper understanding of HfO2-based ferroelectrics, with implications for nonvolatile memories and tunneling devices.
研究不足
The study is limited to specific heterostructures and deposition conditions; the presence of minority phases (e.g., tetragonal or monoclinic) could affect properties. Leakage current issues were noted, and the films are not fully monocrystalline, potentially impacting device performance. Scalability and integration with CMOS processes may require further optimization.
1：Experimental Design and Method Selection:
The study used pulsed laser deposition (PLD) to fabricate heterostructures of HZO/LSMO/LNO/CeO2/YSZ/Si(001) and HZO/LNO/CeO2/YSZ/Si(001). The design aimed to stabilize the orthorhombic phase of HZO on Si(001) using buffer layers to reduce lattice mismatch. Theoretical models for epitaxial growth and ferroelectric properties were employed.
2：1). The design aimed to stabilize the orthorhombic phase of HZO on Si(001) using buffer layers to reduce lattice mismatch. Theoretical models for epitaxial growth and ferroelectric properties were employed.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Silicon (001) substrates were used. Samples were prepared with specific layer sequences to study the effect of bottom electrodes (LSMO vs. LNO). Data were acquired through XRD, AFM, and electrical measurements.
3：List of Experimental Equipment and Materials:
Equipment included a KrF excimer laser for PLD, Siemens D5000 and Bruker D8-Advance diffractometers for XRD, atomic force microscope (AFM), dc magnetron sputtering for electrode deposition, and AixACCT TFAnalyser2000 for electrical characterization. Materials included Hf0.5Zr0.5O2, La0.67Sr0.33MnO3, LaNiO3, CeO2, YSZ, Si wafers, and platinum for electrodes.
4：5Zr5O2, La67Sr33MnO3, LaNiO3, CeO2, YSZ, Si wafers, and platinum for electrodes.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Heterostructures were deposited in a single PLD process at specified temperatures and oxygen pressures. XRD θ-2θ scans, φ-scans, and AFM were used for structural characterization. Platinum top electrodes were sputtered, and ferroelectric properties (polarization loops, fatigue, retention) were measured using the AixACCT platform with DLCC procedure for leakage compensation.
5：Data Analysis Methods:
XRD data were analyzed for phase identification and epitaxial relationships. AFM data provided surface roughness. Electrical data were analyzed for remnant polarization, coercive voltage, retention time, endurance cycles, and leakage current using standard ferroelectric measurement techniques and software tools associated with the equipment.
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