论文标题
在外延菌株下，HFO $ _2 $的竞争铁电阶段的稳定
Stabilization of competing ferroelectric phases of HfO$_2$ under epitaxial strain
论文作者
论文摘要
Hafnia（HFO $ _2 $） - 基于稳健的铁电和与硅的集成，基于纳米级电子设备的薄膜在纳米级电子设备中具有有希望的应用。但是，HFO $ _2 $具有各种稳定和亚稳态的多晶型物，结构和能量非常相似。近年来，识别和稳定HFO $ _2 $的铁电功能阶段引起了密集的研究兴趣。在这项工作中，使用（111）面向的HFO $ _2 $的第一原理计算用于发现在四方相中施加平面剪切应变会诱导非极性到极相变。这种平面剪切诱导的极相显示是已知的亚稳态铁电$ pnm2_1 $ hfo $ _2 $相位的外延失真。建议这种铁电$ PNM2_1 $相位可以说明（111）面向的HFO $ _2 $ _2 $的薄膜[自然材料17，1095-1100（2018）]中最近观察到的铁电性。对HFO $ _2 $中第二个功能性铁电相的进一步研究可能会改善基于逻辑和内存设备的基于$ _2 $的电影的性能。
Hafnia (HfO$_2$)-based thin films have promising applications in nanoscale electronic devices due to their robust ferroelectricity and integration with silicon. However, HfO$_2$ has various stable and metastable polymorphs with quite similar structures and energies. Identifying and stabilizing the ferroelectric functional phases of HfO$_2$ have attracted intensive research interest in recent years. In this work, first-principles calculations on (111)-oriented HfO$_2$ are used to discover that imposing an in-plane shear strain on the tetragonal phase induces a nonpolar to polar phase transition. This in-plane shear-induced polar phase is shown to be an epitaxial distortion of a known metastable ferroelectric $Pnm2_1$ phase of HfO$_2$. It is proposed that this ferroelectric $Pnm2_1$ phase can account for the recently observed ferroelectricity in the (111)-oriented HfO$_2$-based thin film [Nature Materials 17, 1095-1100 (2018)]. Further investigation of this second functional ferroelectric phase in HfO$_2$ could potentially improve the performances of HfO$_2$-based films in logic and memory devices.
