The Si(100) surface can be easily transformed into a \(2\times 1\) reconstruction by desorbing native oxides and other contaminants naturally present on the surface. In order to desorb these contaminants, the wafer is typically heated to \(900^\circ\textrm{C}\) in vacuum. The mechanism for Si(100)\(2\times 1\) is caused by a series of events that act to minimize the surface energy by minimizing the number of dangling bonds on the surface.
Each pair of adjacent atoms bond together, forming rows of dimers. Each atom in a dimer has a single dangling bond. The surface free energy is lower than its naturally suspended hydrogen-bonded state, and the surface structure has \(2\times 1\) diperiodicity.
Figure 1.14: Si(100)\(2\times 1\) Reconstruction. The Si(100) \(1\times 1\) surface is reconstructed to \(2\times 1\) by the formation of Si dimers. a) A planar view of the dimerized surface (dark) atoms, and b) a cross sectional view of the surface illustrating atomic depth. |
