1. Impact of Zr substitution on the electronic structure of ferroelectric hafnia.
- Author
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Huang, Jinhai, Mao, Ge-Qi, Xue, Kan-Hao, Yang, Shengxin, Ye, Fan, Sun, Huajun, and Miao, Xiangshui
- Subjects
ELECTRONIC band structure ,HAFNIUM oxide ,BRILLOUIN zones ,CONDUCTION bands ,DIELECTRIC breakdown - Abstract
HfO
2 -based dielectrics are promising for nanoscale ferroelectric applications, and the most favorable material within the family is Zr-substituted hafnia, i.e., Hf1−x Zrx O2 (HZO). The extent of Zr substitution can be great, and x is commonly set to 0.5. However, the bandgap of ZrO2 is lower than HfO2 , thus it is uncertain how the Zr content should influence the electronic band structure of HZO. A reduced bandgap is detrimental to the cycling endurance as charge injection and dielectric breakdown would become easier. Another issue is regarding the comparison on the bandgaps between HfO2 /ZrO2 superlattices and HZO solid-state solutions. In this work, we systematically investigated the electronic structures of HfO2 , ZrO2 , and HZO using self-energy corrected density functional theory. In particular, the conduction band minimum of Pca21 -HfO2 is found to lie at an ordinary k-point on the Brillouin zone border, not related to any interlines between high-symmetry k-points. Moreover, the rule of HZO bandgap variation with respect to x has been extracted. The physical mechanisms for the exponential reduction regime and linear decay regime have been revealed. The bandgaps of HfO2 /ZrO2 ferroelectric superlattices are investigated in a systematic manner, and the reason why the superlattice could possess a bandgap lower than that of ZrO2 is revealed through comprehensive analysis. [ABSTRACT FROM AUTHOR]- Published
- 2023
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