Jalil Abdur Rehman, Hou Xiao, Schüffelgen Peter, Bae Jin Hee, Neumann Elmar, Mussler Gregor, Plucinski Lukasz, Grützmacher Detlev
Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany.
JARA-FIT (Fundamentals of Future Information Technology), Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany.
Nanomaterials (Basel). 2023 Jul 24;13(14):2143. doi: 10.3390/nano13142143.
Over the past three decades, the growth of Bi thin films has been extensively explored due to their potential applications in various fields such as thermoelectrics, ferroelectrics, and recently for topological and neuromorphic applications, too. Despite significant research efforts in these areas, achieving reliable and controllable growth of high-quality Bi thin-film allotropes has remained a challenge. Previous studies have reported the growth of trigonal and orthorhombic phases on various substrates yielding low-quality epilayers characterized by surface morphology. In this study, we present a systematic growth investigation, enabling the high-quality growth of Bi epilayers on Bi-terminated Si (111) 1 × 1 surfaces using molecular beam epitaxy. Our work yields a phase map that demonstrates the realization of trigonal, orthorhombic, and pseudocubic thin-film allotropes of Bi. In-depth characterization through X-ray diffraction (XRD) techniques and scanning transmission electron microscopy (STEM) analysis provides a comprehensive understanding of phase segregation, phase stability, phase transformation, and phase-dependent thickness limitations in various Bi thin-film allotropes. Our study provides recipes for the realization of high-quality Bi thin films with desired phases, offering opportunities for the scalable refinement of Bi into quantum and neuromorphic devices and for revisiting technological proposals for this versatile material platform from the past 30 years.
在过去三十年中，由于铋（Bi）薄膜在热电、铁电等各个领域以及最近在拓扑和神经形态应用中的潜在应用，其生长过程得到了广泛研究。尽管在这些领域进行了大量研究工作，但实现高质量Bi薄膜同素异形体的可靠且可控生长仍然是一项挑战。先前的研究报道了在各种衬底上生长三角相和正交相，得到的外延层质量较低，其特征在于表面形态。在本研究中，我们进行了系统的生长研究，利用分子束外延技术在Bi端接的Si(111) 1×1表面上实现了高质量Bi外延层的生长。我们的工作得到了一个相图，展示了Bi的三角相、正交相和伪立方薄膜同素异形体的实现。通过X射线衍射（XRD）技术和扫描透射电子显微镜（STEM）分析进行的深入表征，全面了解了各种Bi薄膜同素异形体中的相分离、相稳定性、相变以及相依赖的厚度限制。我们的研究提供了实现具有所需相的高质量Bi薄膜的方法，为将Bi可扩展地优化到量子和神经形态器件中以及重新审视过去30年中针对这个多功能材料平台的技术方案提供了机会。
