Crystal Structures and Electrical Properties of Epitaxial BiFeO3 Thin Films with (001), (110), and (111) Orientations
Crystal Structures and Electrical Properties of Epitaxial BiFeO3 Thin Films with (001), (110), and (111) Orientations
复制标题
DOI：
10.1143/jjap.49.09mb03
复制
发表时间：
2010-09
影响因子：
1.5
通讯作者：
Keita Sone;H. Naganuma;T. Miyazaki;T. Nakajima;S. Okamura
中科院分区：
文献类型：
--
作者：
Keita Sone;H. Naganuma;T. Miyazaki;T. Nakajima;S. Okamura
在 (001)、(110) 和 (111) La 掺杂 SrTiO3 单晶衬底上形成 BiFeO3 (BFO) 薄膜。所有薄膜都是外延生长的并且主要具有菱面体结构。在(001)基板上形成的BFO膜仅具有(001)成分，而在(110)和(111)基板上形成的BFO膜分别具有(110)和(111)成分。 (001)、(110)和(111)外延BFO薄膜的剩余极化分别为63、84和106 µC/cm2。看来，通过施加外部电压，(110)和(111)分量分别变为(110)和(111)分量。 (001)外延BFO薄膜的电性能表现出明显的不对称性。结果发现(001)外延BFO薄膜具有薄的四方层，其自发极化方向固定在靠近衬底的向下方向。最后我们得出结论，这个四方层导致了界面处空间电荷的积累，从而产生了向下的内建场。向下的内建场有利于向上偏振的切换并引起不对称弛豫。
BiFeO3 (BFO) films were formed on (001), (110), and (111) La-doped SrTiO3 single-crystal substrates. All the films were epitaxially grown and had mainly rhombohedral structure. The BFO film formed on the (001) substrate had only a (001) component whereas the BFO films on (110) and (111) substrates had (110) and (111) components, respectively. The (001), (110), and (111) epitaxial BFO films showed the remanent polarizations of 63, 84, and 106 µC/cm2, respectively. It seems that the (110) and (111) components were changed to (110) and (111) ones, respectively, by applying an external voltage. The (001) epitaxial BFO film showed marked asymmetry in its electrical properties. It was found that the (001) epitaxial BFO film had a thin tetragonal layer with spontaneous polarization fixed in the downward direction near the substrate. Finally, we concluded that this tetragonal layer caused the accumulation of space charges at the interface, causing a downward built-in field to be generated. The downward build-in field facilitated the switching of upward polarization and caused asymmetric relaxation.