What is surface reconstruction in silicon?

Surface reconstruction in silicon is a process in which surface atoms rearrange their positions when the material is heated to high temperatures in a vacuum. This phenomenon occurs because the atoms at the surface seek a more stable configuration than they would have in a bulk-terminated lattice.1

The nature of this reconstruction depends on the specific crystal face:

• Silicon (111): This surface undergoes an intricate and complex rearrangement known as the Takayanagi 7 × 7 structure. The scanning tunneling microscope (STM) has been instrumental in measuring the chemical reactivity, electronic configuration, and precise position of each atomic site within this pattern.1
• Silicon (100): This reconstruction is simpler, characterized by surface atoms forming pairs, or dimers, that align into rows extending across the surface.1

By studying these reconstructions, scientists can better understand the atomic-scale properties of semiconductor surfaces.1