Complete three-dimensional structure of Bi-adsorbed Si(110) surface: Discovery of heavily reconstructed Si(110) substrate

Hiroaki Aoyama,Tadashi Abukawa

doi:10.1103/physrevresearch.3.043164

Abstract

Silicon is one of the most well-studied crystals in terms of surface structure. In particular, the three low Miller index surfaces---(100), (110), and (111)---which are located at the three apexes of the triangle of the irreducible orientation of the cubic crystal, are the most fundamental and have been extensively studied. However, the surface structure on Si(110) substrates is not as well understood as on other substrates. Here, we have investigated a surface structure induced by submonolayer Bi deposition on Si(110). The complete atomic arrangement from the surface to the fifth layer was directly determined by solving the Patterson function, which was obtained using a very large number of electron diffraction patterns. In contrast to the case of the Si(111) substrate, the Si(110) substrate showed significant reconstructions under a Bi overlayer. The obtained structure shows how dangling bonds can be reduced at the Si(110) substrate. The present result proves the high capability of the surface structure determination of the present method.

Highlights

The surfaces of covalent crystals such as Si and Ge are typically reconstructed to reduce unstable broken bonds, i.e., dangling bonds (DBs), created by crystal truncation
Except for the strong peak at the origin, the structure in P(r) at r < 1.5 Å should be an artifact caused by the experimental limitations, such as the limited range or inhomogeneous sensitivity of the screen because no reasonable interatomic bond smaller than 1.5 Å is expected in the present surface
Important slices of |P(r)| are shown in Fig. 7 with the simulated |P(r)| for the present structural model

Summary

Introduction

The surfaces of covalent crystals such as Si and Ge are typically reconstructed to reduce unstable broken bonds, i.e., dangling bonds (DBs), created by crystal truncation. The atomic arrangement of the 7 × 7 structure, including the reconstruction from the surface to the third layer, was determined by Takayanagi et al in 1985 after various studies by many researchers [3,4]. Another low-index surface, Si(100), shows a centered 4 × 2 superstructure in the ground state, and a buckled Si dimer model is accepted for this surface [6,7,8,9,10]. Since the structure of the clean surface has not been determined yet, the surface

Methods

Results

Conclusion