Structural determination of the Bi(110) semimetal surface by LEED analysis andab initiocalculations

J Sun,Ph Hofmann,Y M Koroteev,D L Adams,M Fuglsang Jensen,E V Chulkov,K Pohl,A Mikkelsen,G Bihlmayer

doi:10.1103/physrevb.74.245406

Abstract

The surface structure of Bi(110) has been investigated by low-energy electron diffraction intensity analysis and by first-principles calculations. Diffraction patterns at a sample temperature of $110\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and normal incidence reveal a bulk truncated $(1\ifmmode\times\else\texttimes\fi{}1)$ surface without indication of any structural reconstruction despite the presence of dangling bonds on the surface layer. Good agreement is obtained between the calculated and measured diffraction intensities for this surface containing only one mirror-plane symmetry element and a buckled bilayer structure. No significant interlayer spacing relaxations are found. The Debye temperature for the surface layer is found to be lower than in the bulk, which is indicative of larger atomic vibrational amplitudes at the surface. Meanwhile, the second layer shows a Debye temperature close to the bulk value. The experimental results for the relaxations agree well with those of our first-principles calculation.

Highlights

Characteristic of group-V elements, bismuth crystallizes in the rhombohedral A7 structure as a semimetal with a small density of states at the Fermi level.1 But interestingly, the surfaces of Bi show very different electronic properties from the bulk
The surface structure of Bi110͒ has been investigated by low-energy electron diffraction intensity analysis and by first-principles calculations
The Debye temperature for the surface layer is found to be lower than in the bulk, which is indicative of larger atomic vibrational amplitudes at the surface

Summary

Introduction

Characteristic of group-V elements, bismuth crystallizes in the rhombohedral A7 structure as a semimetal with a small density of states at the Fermi level. But interestingly, the surfaces of Bi show very different electronic properties from the bulk. It turns out that on most semiconductor surfaces the atoms rearrange their positions such that the dangling bonds are removed and the surface is again a semiconductor and not a metal.. It turns out that on most semiconductor surfaces the atoms rearrange their positions such that the dangling bonds are removed and the surface is again a semiconductor and not a metal.9 Semimetals such as bismuth lie in between these two cases. There is a very small overlap between both bands such that the material is formally a metal This delicate balance between being a metal and a semiconductor depends crucially on the atomic structure and it can be expected to be severely disturbed at the surface

Methods

Results

Conclusion