Zhang Yan, Fan Zhen, Wang Dao, Wang Jiali, Zou Zhengmiao, Li Yushan, Li Qiang, Tao Ruiqiang, Chen Deyang, Zeng Min, Gao Xingsen, Dai Jiyan, Zhou Guofu, Lu Xubing, Liu Jun-Ming
Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
Guangdong Provincial Key Laboratory of Optical Information Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40510-40517. doi: 10.1021/acsami.0c10964. Epub 2020 Aug 26.
A capping layer is known to be critical for stabilizing the ferroelectric (FE) orthorhombic phase (o-phase) in a HfO-based thin film. Here, vanadium oxide (VO), a functional oxide exhibiting the insulator-metal transition, is used as a novel type of a capping layer for the HfZrO (HZO) thin film. It is demonstrated that the VO capping layer (VCL) can enhance the FE properties of the HZO thin film comprehensively. Specifically, the HZO thin film with a VCL shows large remanent polarization (2 ≈36.9 μC/cm), relatively small coercive field ( ≈1.09 MV/cm), high endurance (up to 10 cycles), and long retention (>10 seconds). The enhanced FE properties may be attributed to the VCL-induced stabilization of the FE o-phase and suppression of oxygen vacancies at the interface. Furthermore, the HZO thin film with a VCL exhibits a successive rightward shift of polarization-voltage () hysteresis loop as the temperature increases. This is well correlated with the insulator-metal transition in a VCL, which can modulate the interfacial built-in field and thus cause the loop shift. It is therefore demonstrated that a VCL not only enhances the FE properties of HZO thin films but also provides a temperature degree of freedom to modulate the FE properties, which may open up a new pathway to develop HfO-based FE memories with high performance and novel functionalities.
众所周知，盖帽层对于稳定基于HfO的薄膜中的铁电（FE）正交相（o相）至关重要。在此，氧化钒（VO）作为一种呈现绝缘体-金属转变的功能氧化物，被用作HfZrO（HZO）薄膜的新型盖帽层。结果表明，VO盖帽层（VCL）能够全面增强HZO薄膜的铁电性能。具体而言，具有VCL的HZO薄膜表现出较大的剩余极化（2≈36.9μC/cm）、相对较小的矫顽场（≈1.09MV/cm）、高耐久性（高达10次循环）以及长保持时间（>10秒）。增强的铁电性能可能归因于VCL诱导的铁电o相稳定以及界面处氧空位的抑制。此外，随着温度升高，具有VCL的HZO薄膜的极化-电压（）滞后回线呈现连续向右移动。这与VCL中的绝缘体-金属转变密切相关，该转变可调节界面内建电场，从而导致滞后回线移动。因此证明，VCL不仅增强了HZO薄膜的铁电性能，还提供了一个温度自由度来调节铁电性能，这可能为开发具有高性能和新颖功能的基于HfO的铁电存储器开辟一条新途径。
