EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Heavier group-IV element bismuth ultrathin films exhibit numerous interesting properties such as strong SOC, high carrier mobility at RT and large Fermi wavelength. These properties constitute Bi films as possible candidates for exploitation of dissipation-less spin channels for both electronics and spintronics applications.
Bi films on HfTe2/InAs(111) templates were grown by molecular beam epitaxy (MBE) and the atomic and electronic structures were studied by Reflection High Energy Electron Diffraction (RHEED), Scanning Tunneling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS), Angle-Resolved Photoemission Spectroscopy (ARPES) and Raman Spectroscopy.
At 6.5 Å of Bi deposition, atomically flat Bi islands with triangular and rectangular shapes are formed. Atomic resolution STM images on the rectangular islands show the presence of both BP-distorted α-Bi and BP α-Bi phases [1-3], while the triangular areas consist of hexagonal β-Bi phase. The mixed phases are confirmed by ARPES measurements [4].
At 12Å Bi deposition high-quality epitaxial growth of 3BLs β-Bi is achieved as verified by STM. The ARPES data of 3BLs shows the band structure of pure Bi(111) phase, while DFT calculated bands of 3BLs freestanding Bi(111) fit well will the experimental results. Thus, the 2D HfTe2 template [5] favors the formation of hexagonal Bi(111) for even the low thickness of 3 BLs.
3BLs Bi film was successfully capped by AlOx layer and ex-situ Raman measurements verified the presence of hexagonal Bi(111) phase. XPS after air exposure showed that 3BLs Bi film was protected by AlOx capping, which is crucial for future applications.

1. E. Akturk et al., Phys. Rev. B 94, 014115 (2016).
2. Y. Lu et al., Nano Lett. 15, 80 (2015).
3. P. J. Kowalczyk et al., Nano Lett. 13, 43 (2012).
4. G. Bian et al. Phys Rev. B 80, 245407 (2009).
5. S. A. Giamini et al., 2D Mater. 4, 015001 (2017).