Determination of Dynamic Parameters Controlling Atomic Scale Etching of Si(100)-( 2×1) by Chlorine

Scanning tunneling microscopy shows that Cl-induced pitting of $\mathrm{Si}\left(100\right)-(2\times 1)$ is initiated by the creation of single dimer vacancies on terraces. These pits grow laterally by dimer removal either along the dimer row or from an adjacent row. Quantitative analysis of the vacancy size distribution shows that the rate constant for linear growth is $4.7\pm 1$ times that for branch creation at 850 K. This indicates that the difference in dimer removal energy in these two directions is $0.11\pm 0.02\mathrm{eV}$, a difference that accounts for the observed surface morphologies.