Year: 2025
Type: preprint
Abstract: Fluorite oxides such as HfO$_2$ exhibit rich and tunable phase behavior, making them promising candidates for next generation electronic devices. A key challenge is to design amorphous HfO$_2$-based high-$k$ materials with both structural and performance stability. Here, using molecular dynamics simulations supported by experimental measurements, we reveal that Ba doping stimulates a polyamorphic transition in HfO$_2$, yielding a semi-ordered amorphous (SA) phase characterized by disordered oxygens embedded within an ordered metal sublattice. We find that this phase arises from degenerate short-range symmetry breaking modes, consistent with Pauling's parsimony rule. Notably, the SA structure is thermodynamically stable and displays a wider bandgap and higher dielectric constant than conventional random-packing amorphous structure, owing to suppressed subgap states and increased Born effective charges. We further demonstrate that this structural motif generalizes to Ba-, Sr-, and Ca-doped HfO$_2$ and ZrO$_2$, establishing a broadly applicable strategy for designing high-performance amorphous dielectrics.
Source: arXiv (Cornell University)
Authors: Yang, Hao, Luan, Qiaotong, Zhang, Qing, Yue, Yuhao, Xu, Yawen, Liu, Xiaohui, Wen, Zheng, Sun, Zhaoru
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6979225429
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