研究目的
To investigate the structural quality of LuFeO3 epitaxial layers grown by pulsed-laser deposition on sapphire substrates with and without platinum Pt interlayers, focusing on the parameters of the structure such as size and misorientation of mosaic blocks as functions of the thickness of LuFeO3 during growth and for different thicknesses of platinum interlayers up to 40 nm.
研究成果
The structural quality of the LuFeO3 layers improves with the growing thickness of the Pt interlayer. This finding shows the possibility of deposition of multiferroic LuFeO3 on a bottom Pt electrode and opens the way for fabricating functional multiferroic structures.
研究不足
The rms roughnesses determined from the XRR data are burdened with a large statistical error, making their values not conclusive. The accurate determination of the in-plane lattice parameters was challenging due to the weakness of diffracted intensities of LFO (108).
1：Experimental Design and Method Selection
The study utilized in situ high-resolution X-ray diffraction (reciprocal-space mapping) to investigate the structural quality of LuFeO3 epitaxial layers. The growth was monitored using pulsed-laser deposition (PLD) with a frequency quadrupled Nd:YAG laser.
2：Sample Selection and Data Sources
Hexagonal h-LuFeO3 films of 10 nm thickness were deposited directly on an Al2O3 (0001) substrate and on Pt interlayers with thicknesses varying between 10 nm and 40 nm. The samples were investigated by XRD and XRR in situ during the PLD growth.
3：List of Experimental Equipment and Materials
The PLD chamber was equipped with entrance and exit Beryllium windows for X-ray beam access. A reflection high-energy electron diffraction system (RHEED) was used to monitor the growth. The chamber was combined with the heavy-duty diffractometer at nano beamline on the synchrotron facility Kara.
4：Experimental Procedures and Operational Workflow
The PLD growth of the Pt interlayer was carried out in high vacuum at a temperature of 300 °C, while the LFO layers were deposited at a substrate temperature of 900 °C and an oxygen background pressure of 0.27 mbar. The samples were slowly cooled down from the growth temperature to room temperature with a cooling rate of 5 °C/min.
5：Data Analysis Methods
The XRR curves were fitted to a standard model of a multilayer with rough interfaces to determine the thicknesses of the Pt and LFO layers, their densities, and root-mean square (rms) roughnesses of the interfaces. The diffracted intensity was expressed as a sum of coherent and diffuse parts.
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