论文标题
由电荷氧空位促进的结构多态性动力学在HFO $ _2 $中
Structural Polymorphism Kinetics Promoted by Charged Oxygen Vacancies in HfO$_2$
论文作者
论文摘要
诸如氧气空位之类的缺陷被普遍认为对于基于HFO2的设备的性能至关重要，但具有各种外来作用（例如唤醒和流体烙印）的原子机制仍然难以捉摸。在这里，在晶格模式匹配标准的指导下，我们通过使用首先基于基于第一原则的可变元素可变的弹性弹性弹性技术来绘制最小能量途径，从而系统地研究Hafnia不同多晶型hafnia之间的相变。我们发现，带正电荷的氧空位可以实质上促进各种非极相向极相的过渡，这是通过瞬时高能四方相和极性$ pca2_1 $相的极端电荷 - 载流子互联性启用的。结构多态性动力学和氧空位的电荷状态之间的复杂耦合对HFO $ _2 $ _2 $的薄膜以及唤醒，流体印记和惯性开关的铁电性起源具有重要意义。
Defects such as oxygen vacancy are widely considered to be critical for the performance of HfO2-based devices, and yet atomistic mechanisms underlying various exotic effects such as wake-up and fluid imprint remain elusive. Here, guided by a lattice-mode-matching criterion, we systematically study the phase transitions between different polymorphs of hafnia under the influences of neutral and positively charged oxygen vacancies by mapping out the minimum energy pathways using a first-principles-based variable-cell nudged elastic band technique. We find that the positively charged oxygen vacancy can substantially promote the transition of various nonpolar phases to the polar phase kinetically, enabled by a transient high-energy tetragonal phase and extreme charge-carrier-inert ferroelectricity of the polar $Pca2_1$ phase. The intricate coupling between structural polymorphism kinetics and the charge state of the oxygen vacancy has important implications for the origin of ferroelectricity in HfO$_2$-based thin films as well as wake-up, fluid imprint, and inertial switching.
