ε-Ga2O3 中自发极化的外延反转
Epitaxial inversion of spontaneous polarization in ε-Ga2O3
- Nanjing University of Posts and Telecommunications（南京邮电大学）
- The Hong Kong University of Science and Technology (Guangzhou)（香港科技大学（广州））
- The Hong Kong University of Science and Technology（香港科技大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过衬底工程实现ε-Ga2O3自发极化矢量的确定与宏观极性控制，建立原子构型识别标准，在AlN和蓝宝石上分别获得均匀Ga极性和O极性外延，为极化电子学奠定基础。
AI中文摘要：
极性宽禁带半导体具有操控内建电场和诱导二维电子气（2DEG）的独特能力。新兴的正交晶系 ε-Ga2O3 因其大的自发极化（Psp）而成为有前景的候选材料。然而，围绕其绝对 Psp 矢量的基本歧义以及无法控制其外延方向，阻碍了该材料的开发利用。在此，我们展示了通过衬底工程解决 ε-Ga2O3 中绝对 Psp 矢量并控制其宏观极性的方法。通过将干涉压电响应与原子构型相关联，我们建立了一个识别标准，即在一个不对称的四原子序列中，通过几何高度差来分配相反的极性。在此特征的指导下，我们证明在 Al 极性 AlN 和蓝宝石上的外延分别产生均匀的 Ga 极性（向上 Psp）和 O 极性（向下 Psp）结构，而结晶度变差会破坏这种对应关系并引发混合极性。这种从原子到宏观的关联消除了非中心对称氧化物中关于绝对极性取向的长期歧义。类似于成熟的 III 族氮化物结构，这一蓝图为设计异质界面处的宏观极化不连续性提供了基础平台，从而释放 ε-Ga2O3 在先进极化电子学中的应用潜力。
英文摘要：
Polar wide bandgap semiconductors offer the unique capability to manipulate internal electric fields and induce two-dimensional electron gases (2DEG). The emerging orthorhombic ε-Ga2O3 is a promising candidate owing to its large spontaneous polarization (Psp). However, exploiting this material is hindered by fundamental ambiguities surrounding its absolute Psp vectors and the inability to govern its epitaxial direction. Here we show the resolution of the absolute Psp vectors in ε-Ga2O3 and control of its macroscopic polarity via substrate engineering. By correlating interferometric piezoresponse with atomic configurations, we establish an identification criterion where opposing polarities are assigned through the geometric elevation within an asymmetric four-atom sequence. Guided by this signature, we demonstrate that epitaxy on Al-polar AlN and sapphire yields uniformly Ga-polar (upward Psp) and O-polar (downward Psp) architectures, respectively, whereas deteriorated crystallinity disrupts this registry and triggers mixed-polarity. This atomic-to-macroscopic correlation eliminates long-standing ambiguities regarding absolute polar orientations in non-centrosymmetric oxides. Analogous to mature III-Nitride architectures, this blueprint provides the foundational platform for designing macroscopic polarization discontinuities at heterointerfaces, unlocking ε-Ga2O3 for advanced polarization electronics.
