Effects of La-Doped HfO₂ Films on Dielectric Properties by Sol-Gel Method

Abstract

HfO₂ and La-doped HfO₂ with 20, 40, 50, and 60 mol% were deposited on silicon wafers by spin-coating technique. The crystallization process was annealed temperature at 600 °C. Then, characterization techniques of XRD, AFM, SEM, Full-field XRF imaging, and XAS were applied to reveal structural morphology, local structure, grain, distribution, etc. This study aims to investigate the effect of doping La into the HfO₂ system on surface formation, microstructure, and dielectric properties. According to the results, RMS surface roughness, and grain size increased relative to La concentration levels. These films demonstrated homogeneous, low surface roughness, and crack-free. The XRD confirms the existence of the monoclinic phase in pure HfO₂ and the mixture phase of the monoclinic and orthorhombic phases in La-doped HfO₂ films. Increasing La concentration caused the structural transformation, the XAS of La L₃-edge indicating that lanthanum remained in the HfO₂ system. Dielectric response based on interface-phase polarization was improved with La content from 0 mol% to 60 mol%. Compared with HfO₂ film, the dielectric constant of La-doped HfO₂ films was increased and dielectric loss was decreased.

Keywords:

• La-doped HfO₂
• phase changes
• dielectric constant
• full-field XRF
• dielectric loss

Acknowledgments

This work is supported by the Suranaree University of Technology (SUT) by the Office of the Higher Education Commission under the NRU Project of Thailand and Synchrotron Light Research Institute (Public Organization) at BL 6A, SLRI, Thailand, for all facilities and financial supports. The authors also acknowledging the BL8: Full-field XRF and BL1.1W: XAS scientists and technicians for their help throughout the experimental support and set-up. The figures in this article were created using Adobe Illustrator, SketchUp, BioRender, and Microsoft PowerPoint.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.