Yang Hailin, Wu An, Yi Huaxin, Cao Weiwei, Yao Jiandong, Yang Guowei, Zou Yi-Chao
School of Materials Science & Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, Sun Yat-sen University Guangzhou 510275 P. R. China
Nanoscale Adv. 2022 Dec 15;5(3):693-700. doi: 10.1039/d2na00835a. eCollection 2023 Jan 31.
Two-dimensional (2D) magnetic materials are of wide research interest owing to their promising applications in spintronic devices. Among them, chromium chalcogenide compounds are some of the limited available systems that present both high stability in air and high Curie temperatures. Epitaxial growth techniques based on chemical vapour deposition (CVD) have been demonstrated to be a robust method for growing 2D non-layered chromium chalcogenides. However, the growth mechanism is not well-understood. Here, we demonstrate the epitaxial growth of CrTe nanoplates with high quality on mica. Atomic-resolution scanning transmission electron microscopy (STEM) imaging reveals that the epitaxial growth is based on nanosized chromium oxide seed particles at the interface of CrTe and mica. The chromium oxide nanoparticle exhibits a coherent interface with both mica and CrTe with a lattice mismatch within 3%, suggesting that, as a buffer layer, chromium oxide can release the interfacial strain, and induce the growth of CrTe although there is a distinct oxygen-content difference between mica and CrTe. This work provides an experimental understanding behind the epitaxial growth of 2D magnetic materials at the atomic scale and facilitates the improvement of their growth procedures for devices with high crystalline quality.
二维（2D）磁性材料因其在自旋电子器件中的应用前景而受到广泛研究关注。其中，硫族化铬化合物是少数在空气中具有高稳定性且居里温度较高的可用体系。基于化学气相沉积（CVD）的外延生长技术已被证明是生长二维非层状硫族化铬的一种可靠方法。然而，其生长机制尚未得到很好的理解。在此，我们展示了在云母上高质量外延生长CrTe纳米片。原子分辨率扫描透射电子显微镜（STEM）成像表明，外延生长基于CrTe与云母界面处的纳米级氧化铬籽晶颗粒。氧化铬纳米颗粒与云母和CrTe均呈现相干界面，晶格失配在3%以内，这表明，作为缓冲层，氧化铬可以释放界面应变，并诱导CrTe生长，尽管云母和CrTe之间存在明显的氧含量差异。这项工作提供了二维磁性材料在原子尺度外延生长背后的实验理解，并有助于改进其用于高晶体质量器件的生长工艺。
