Wang Yiping, Sun Xin, Chen Zhizhong, Cai Zhonghou, Zhou Hua, Lu Toh-Ming, Shi Jian
Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Department of Physics, Applied Physics, and Astronomy Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Sci Adv. 2018 May 25;4(5):eaar3679. doi: 10.1126/sciadv.aar3679. eCollection 2018 May.
The success of strain engineering has made a step further for the enhancement of material properties and the introduction of new physics, especially with the discovery of the critical roles of strain in the heterogeneous interface between two dissimilar materials (for example, FeSe/SrTiO). On the other hand, the strain manipulation has been limited to chemical epitaxy and nanocomposites that, to a large extent, limit the possible material systems that can be explored. By defect engineering, we obtained, for the first time, dense three-dimensional strongly correlated VO epitaxial nanoforest arrays that can be used as a novel "substrate" for dynamic strain engineering, due to its metal-insulator transition. The highly dense nanoforest is promising for the possible realization of bulk strain similar to the effect of nanocomposites. By growing single-crystalline halide perovskite CsPbBr, a mechanically soft and emerging semiconducting material, onto the VO, a heterogeneous interface is created that can entail a ~1% strain transfer upon the metal-insulator transition of VO. This strain is large enough to trigger a structural phase transition featured by PbX octahedral tilting along with a modification of the photoluminescence energy landscape in halide perovskite. Our findings suggest a promising strategy of dynamic strain engineering in a heterogeneous interface carrying soft and strain-sensitive semiconductors that can happen at a larger volumetric value surpassing the conventional critical thickness limit.
应变工程的成功为增强材料性能和引入新物理特性又迈进了一步，特别是随着应变在两种不同材料（例如，FeSe/SrTiO）的异质界面中的关键作用的发现。另一方面，应变操纵一直局限于化学外延和纳米复合材料，这在很大程度上限制了可探索的可能材料体系。通过缺陷工程，我们首次获得了致密的三维强关联VO外延纳米森林阵列，由于其金属-绝缘体转变，该阵列可作为动态应变工程的新型“衬底”。高度致密的纳米森林有望实现类似于纳米复合材料效应的体应变。通过在VO上生长机械柔软且新兴的半导体材料单晶卤化物钙钛矿CsPbBr，创建了一个异质界面，该界面在VO发生金属-绝缘体转变时可实现约1%的应变转移。这种应变足够大，足以引发以PbX八面体倾斜为特征的结构相变，并伴随着卤化物钙钛矿中光致发光能量分布的改变。我们的研究结果表明了一种在承载柔软且应变敏感半导体的异质界面中进行动态应变工程的有前景的策略，这种应变工程可以在超过传统临界厚度极限的更大体积值下发生。
