Surface Modification and Subsequent Fermi Density Enhancement of Bi(111)

Abstract

Defects introduced to the surface of Bi(111) break the translational symmetry and modify the surface states locally. We present a theoretical and experimental study of the 2D defects on the surface of Bi(111) and the states that they induce. Bi crystals cleaved in ultrahigh vacuum (UHV) at low temperature (110 K) and the resulting ion-etched surface are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), and scanning tunneling microscopy (STM) as well as spectroscopy (STS) techniques in combination with density functional theory (DFT) calculations. STS measurements of cleaved Bi(111) reveal that a commonly observed bilayer step edge has a lower density of states (DOS) around the Fermi level as compared to the atomic-flat terrace. Following ion bombardment, the Bi(111) surface reveals anomalous behavior at both 110 and 300 K: Surface periodicity is observed by LEED, and a significant increase in the number of bilayer step edges and energetically unfavorable monolayer steps is observed by STM. It is suggested that the newly exposed monolayer steps and the type A bilayer step edges result in an increase to the surface Fermi density as evidenced by UPS measurements and the Kohn-Sham DOS. These states appear to be thermodynamically stable under UHV conditions.

10 pages, 7 figures. See publisher's website for Supporting Information

References in corpus (11)

• Electric Field Effect in Atomically Thin Carbon Films
• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• The electronic properties of graphene
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Quantum Spin Hall Effect and Enhanced Magnetic Response by Spin-Orbit Coupling
• Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit
• Topological origin of subgap conductance in insulating bilayer graphene
• One-dimensional Topological Edge States of Bismuth Bilayers
• Band Bending and Valence Band Quantization at Line Defects in MoS${}_2$
• Interacting multi-channel topological boundary modes in a quantum Hall valley system

Cited by in corpus (2)

• Reconciling the theoretical and experimental electronic structure of NbO2
• Unravelling the atomic and electronic structure of nanocrystals on superconducting Nb(110): Impact of the oxygen monolayer