| AVS 62nd International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS+AS+NS-WeM |
| Session: | Metals, Alloys & Oxides: Reactivity and Catalysis |
| Presenter: | Hiroyuki Hirayama, Tokyo Institute of Technology, Japan |
| Authors: | I. Kokubo, Tokyo Institute of Technology, Japan Y. Yoshiike, Tokyo Institute of Technology, Japan K. Shishikura, Tokyo Institute of Technology, Japan K. Nakatsuji, Tokyo Institute of Technology, Japan H. Hirayama, Tokyo Institute of Technology, Japan |
| Correspondent: | Click to Email |
Bismuth (Bi) takes the rhombohedral (A7) crystalline structure in bulk. However, it also takes the black phosphorous (BP) structure in ultrathin films. Theoretically, a few bilayer thick Bi(110) films with the BP structure were predicted to be a nontrivial two-dimensional topological insulator by removing the buckling at the surfaces [1]. In the meantime, ultrathin Bi(110) films with the A7 structure was suggested to realize the Dirac electron system at the surfaces [2]. From these viewpoints, the growth, structure, and electronic states of the Bi(110) ultra-thin films are of great interest. In this study, we investigated the details of the atomic arrangements and electronic states at the Bi(110) islands on the Si(111)√3 × √3-B substrate experimentally using scanning tunneling microscope (STM) [3] and angle-resolved photoelectron spectroscopy (ARPES) in a synchrotron radiation facility.
In the study, we found that atomically flat, long, narrow Bi(110) islands grew along specific orientations on the Si(111) )√3 × √3-B substrate. The orientations belonged to one of the two sets of three-fold rotational axes, which differed by 26° each other. The preference of the specific orientations were reasonably attributed to the commensuration of the diagonal of the rectangular Bi(110) lattice to the √3 × √3 substrate unit cell. The islands grew as to make their edges parallel to the short side of the Bi(110) rectangular unit cell. The combination of the Bi domains of different orientations caused various types of boundaries on the wide terraces of the Bi(110) islands. In particular, the domains along ±87° from the {1-10} direction were found to be connected perfectly on the atomic scale at the straight boundary by inserting a local switching of the bond direction to the zigzag chains of the in-plane bonds. On the Si(111) )√3 × √3-B substrate, both the odd layer thick A7 and even layer thick BP Bi(110) islands appeared. The dispersive surface bands and their Fermi surface mapping with characteristic electron and hole pockets were observed in ARPES spectra. Details will be reported in the presentation.
[1] Y. Lu, W. Xu, M. Zeng, G. Yao, L. Shen, M. Yang, Z. Luo, F. Pan, K. Wu, T. Das, P. He, J. Jiang, J. Martin, Y. P. Feng, H. Lin, X. Wang, Nano Lett. 15, 80 (2015).
[2] G. Bian, X. Wang, T. Miller, T. -C. Chiang, P. J. Kowalczyk, O. Mahapatra, S. A. Brown, Phys. Rev. B 90, 195409 (2014).
[3] I. Kokubo, Y. Yoshiike, K. Nakatsuji, H. Hirayama, Phys. Rev. B 91, 075429 (2015).
}