Abstract
We have incrementally grown bismuth thin films onto a n-doped Ge(111) substrate. Low energy electron diffraction reveals that the first Bi atomic layer is characterized by the reconstruction. By angle-resolved photoemission spectroscopy we observe Rashba-split bands that do not cross the Fermi level. At higher coverages, where a Rashba type of splitting should still be present, the density of occupied states close to the Fermi energy gradually increases, while extra diffraction spots, related to Bi(110) islands, appear.
Highlights
Electrons in bismuth, thanks to its high atomic number (ZBi = 83), are subject to a huge spinorbit interaction
Confinement promotes the formation of quantum well-related states [4, 5], while the removal of inversion symmetry at surfaces or interfaces yields a non null Rashba term in the hamiltonian, resulting in spin-polarized surface bands [6,7,8,9]
The Rashba effect is found to be greatly enhanced in one monolayer (ML) of Bi deposited on Ge(111) [7, 8] with respect to the (111) surface of bulk Bi [10]
Summary
Confinement promotes the formation of quantum well-related states [4, 5], while the removal of inversion symmetry at surfaces or interfaces yields a non null Rashba term in the hamiltonian, resulting in spin-polarized surface bands [6,7,8,9]. In this context, important for both fundamental and technological reasons is the deposition of Bi films onto semiconductors. In this work we present an analysis of the structural and electronic properties of ultrathin Bi layers grown on n-doped Ge(111), based on X ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and angle-resolved photoemission (ARPES)
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