The HfO2 ferroelectric-metal heterojunction and its emergent electrostatic potential: comparison with ZrO2 and SiO2

• Type: Article in International Scientific Journal
• Date: 2024

Authors

Maria Helena Braga (Author) FEUP; Antonio Nuno Guerreiro (Author) FEUP

Journal

Title: Journal of Materials Chemistry C

Vol. 12

Pages: 19386-19397

ISSN: 2050-7526

Publisher: Royal Society of Chemistry

Indexing

ISI Web of Knowledge - 0 Citations

ISI Web of Science

Scopus - 0 Citations

Scientific classification

CORDIS: Physical sciences ; Technological sciences

Associated Projects

LAETA2023 - Programático - ET - Emerging Technologies - LAETA2023 - Programático - ET - Emerging Technologies

NGS -New Generation Storage - NGS -New Generation Storage

CVB - CVB - Cadeia de Valor das Baterias em Portugal

Other information

Authenticus ID: P-017-HN0

DOI: 10.1039/d4tc02434f

Abstract (EN): Transistors have been protagonists in the electronic device world since 1948. As miniaturization occurred, new materials, architectures, and fabrication strategies advanced. However, the choice of materials relative to getting the best chance to minimize Boltzmann's tyranny does not yet rely on predicting how the materials work together in heterojunctions. Herein, we show how conductors, Al and Cu, and insulators, ZrO2 and HfO2, in a 2D horizontal contact cell, such as Cu/HfO2/Al, align their surface potentials and, consequently, their chemical potentials besides their electrochemical potentials or Fermi levels, either at the interface or at the individual surfaces away from the interface, depending on the impedance at the interface. The materials show that they are connected and responsive as a system within a cm range. HfO2 may behave as a ferroelectric at nanoparticle sizes or when doped with Zr4+ in HfO2-ZrO2 mixtures. Herein, we show that the mu m-sized loose particles of HfO2 with their stable crystalline structure can equalize their surface potentials and, consequently, their chemical potentials with the metals' counterparts at the heterojunctions, at OCV, or in a closed circuit with a 1 k Omega resistor load, which has only been demonstrated before with ferroionics and ferroelectric glasses. The ability to propagate surface plasmon polaritons (SPPs) at THz-frequencies was also observed, superimposing the equalization of the surface potentials along the materials' interfacial cross-sections. The mu m-sized HfO2 shows a high capacity for polarizing, increasing its dielectric constant to >10(5), while characterized in Cu/HfO2/Al and Cu/HfO2/Cu cells by scanning Kelvin probe (SKP) with the probe at different heights, cyclic voltammetry (CV or I-V), and electrical impedance spectroscopy (EIS). Using ab initio simulations, the optimized crystalline structure and electrical, electrostatic, and thermal properties of HfO2 were determined: electron localization function (ELF), band structure, Fermi surface, thermal conductivity, and chemical potential vs. the number of charge carriers. We highlight that emergent ferroelectric and topologic plasmonic transport was distinctly observed for HfO2 in a horizontal-like cell containing two metal/HfO2 heterojunctions without electromagnetic pump application.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12