Stabilizing polar phases in binary metal oxides by hole doping
Stabilizing polar phases in binary metal oxides by hole doping
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DOI：
10.1103/physrevmaterials.7.044412
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发表时间：
2022-09
影响因子：
3.4
通讯作者：
Tengfei Cao;G. Ren;D. Shao;E. Tsymbal;Rohan Mishra
中科院分区：
文献类型：
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作者：
Tengfei Cao;G. Ren;D. Shao;E. Tsymbal;Rohan Mishra
最近在二元金属氧化物的亚稳相，如HfO2，ZrO2，Hf0.5Zr0.5O2和Ga2O3中观察到的铁电性引起了很多关注。这些亚稳铁电相通常通过外延生长、合金化或缺陷工程来稳定。在这里，我们提出空穴掺杂在稳定二元金属氧化物中的极性相方面起着关键作用。使用第一性原理密度泛函理论计算，我们表明，这些氧化物中的空穴主要占据两个氧亚晶格之一。这种空穴定位在极性相中比在非极性相中更明显，降低了系统的静电能，并使极性相在足够大的浓度下更稳定。我们证明，这种静电机制是负责稳定的铁电相的HfO2 aliotoxins掺杂的元素，引入空穴的系统，如La和N。最后，我们表明，在HfO2的自发极化是强大的空穴掺杂，和一个大的极化仍然存在，即使在高浓度的空穴。
The recent observation of ferroelectricity in the metastable phases of binary metal oxides, such as HfO2, ZrO2, Hf0.5Zr0.5O2, and Ga2O3, has garnered a lot of attention. These metastable ferroelectric phases are typically stabilized through epitaxial growth, alloying, or defect engineering. Here, we propose hole doping plays a key role in stabilizing the polar phases in binary metal oxides. Using first-principles density-functional-theory calculations, we show that holes in these oxides mainly occupy one of the two oxygen sublattices. This hole localization, which is more pronounced in the polar phase than in the nonpolar phase, lowers the electrostatic energy of the system, and makes the polar phase more stable at sufficiently large concentrations. We demonstrate that this electrostatic mechanism is responsible for stabilization of the ferroelectric phase of HfO2 aliovalently doped with elements that introduce holes to the system, such as La and N. Finally, we show that the spontaneous polarization in HfO2 is robust to hole doping, and a large polarization persists even under a high concentration of holes.