- Dai, Liyan;
- Zhao, Jinyan;
- Li, Jingrui;
- Chen, Bohan;
- Zhai, Shijie;
- Xue, Zhongying;
- Di, Zengfeng;
- Feng, Boyuan;
- Sun, Yanxiao;
- Luo, Yunyun;
- Ma, Ming;
- Zhang, Jie;
- Ding, Sunan;
- Zhao, Libo;
- Jiang, Zhuangde;
- Luo, Wenbo;
- Quan, Yi;
- Schwarzkopf, Jutta;
- Schroeder, Thomas;
- Ye, Zuo-Guang;
- Xie, Ya-Hong;
- Ren, Wei;
- Niu, Gang
The integration of complex oxides with a wide spectrum of functionalities on Si, Ge and flexible substrates is highly demanded for functional devices in information technology. We demonstrate the remote epitaxy of BaTiO3 (BTO) on Ge using a graphene intermediate layer, which forms a prototype of highly heterogeneous epitaxial systems. The Ge surface orientation dictates the outcome of remote epitaxy. Single crystalline epitaxial BTO3-δ films were grown on graphene/Ge (011), whereas graphene/Ge (001) led to textured films. The graphene plays an important role in surface passivation. The remote epitaxial deposition of BTO3-δ follows the Volmer-Weber growth mode, with the strain being partially relaxed at the very beginning of the growth. Such BTO3-δ films can be easily exfoliated and transferred to arbitrary substrates like Si and flexible polyimide. The transferred BTO3-δ films possess enhanced flexoelectric properties with a gauge factor of as high as 1127. These results not only expand the understanding of heteroepitaxy, but also open a pathway for the applications of devices based on complex oxides.