Impact of Zr substitution on the electronic structure of ferroelectric hafnia
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866929500468543488 |
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| author | Huang, Jinhai Mao, Ge-Qi Xue, Kan-Hao Yang, Shengxin Ye, Fan Sun, Huajun Miao, Xiangshui |
| author_facet | Huang, Jinhai Mao, Ge-Qi Xue, Kan-Hao Yang, Shengxin Ye, Fan Sun, Huajun Miao, Xiangshui |
| contents | $\mathrm{HfO_2}$-based dielectrics are promising for nanoscale ferroelectric applications, and the most favorable material within the family is Zr-substituted hafnia, i.e., $\mathrm{Hf_{1-x}Zr_xO_2}$ (HZO). The extent of Zr substitution can be great, and x is commonly set to 0.5. However, the band gap of $\mathrm{ZrO_2}$ is lower than $\mathrm{HfO_2}$, thus it is uncertain how the Zr content should influence the electronic band structure of HZO. A reduced band gap is detrimental to the cycling endurance as charge injection and dielectric breakdown would become easier. Another issue is regarding the comparison on the band gaps between $\mathrm{HfO_2}$/$\mathrm{ZrO_2}$ superlattices and HZO solid-state solutions. In this work we systematically investigated the electronic structures of $\mathrm{HfO_2}$, $\mathrm{ZrO_2}$ and HZO using self-energy corrected density functional theory. In particular, the conduction band minimum of $Pca2_1$-$\mathrm{HfO_2}$ 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 band gap variation with respect to x has been extracted. The physical mechanisms for the exponential reduction regime and linear decay regime have been revealed. The band gaps of $\mathrm{HfO_2}$/$\mathrm{ZrO_2}$ ferroelectric superlattices are investigated in a systematic manner, and the reason why the superlattice could possess a band gap lower than that of $\mathrm{ZrO_2}$ is revealed through comprehensive analysis. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2302_03852 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Impact of Zr substitution on the electronic structure of ferroelectric hafnia Huang, Jinhai Mao, Ge-Qi Xue, Kan-Hao Yang, Shengxin Ye, Fan Sun, Huajun Miao, Xiangshui Materials Science $\mathrm{HfO_2}$-based dielectrics are promising for nanoscale ferroelectric applications, and the most favorable material within the family is Zr-substituted hafnia, i.e., $\mathrm{Hf_{1-x}Zr_xO_2}$ (HZO). The extent of Zr substitution can be great, and x is commonly set to 0.5. However, the band gap of $\mathrm{ZrO_2}$ is lower than $\mathrm{HfO_2}$, thus it is uncertain how the Zr content should influence the electronic band structure of HZO. A reduced band gap is detrimental to the cycling endurance as charge injection and dielectric breakdown would become easier. Another issue is regarding the comparison on the band gaps between $\mathrm{HfO_2}$/$\mathrm{ZrO_2}$ superlattices and HZO solid-state solutions. In this work we systematically investigated the electronic structures of $\mathrm{HfO_2}$, $\mathrm{ZrO_2}$ and HZO using self-energy corrected density functional theory. In particular, the conduction band minimum of $Pca2_1$-$\mathrm{HfO_2}$ 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 band gap variation with respect to x has been extracted. The physical mechanisms for the exponential reduction regime and linear decay regime have been revealed. The band gaps of $\mathrm{HfO_2}$/$\mathrm{ZrO_2}$ ferroelectric superlattices are investigated in a systematic manner, and the reason why the superlattice could possess a band gap lower than that of $\mathrm{ZrO_2}$ is revealed through comprehensive analysis. |
| title | Impact of Zr substitution on the electronic structure of ferroelectric hafnia |
| topic | Materials Science |
| url | https://arxiv.org/abs/2302.03852 |