Structural model of Si(100)-c(4×4)

The $c(4\mathrm{}\times 4)$ reconstruction of Si(100) clean surface has been obtained by suitable thermal annealing within the temperature range of 580-630°C. The structure transition between $c(4\mathrm{}\times 4)$ and (2×1) has been observed. From the experimental result of hydrogen adsorption that the $c(4\mathrm{}\times 4)$ structure could not convert into (2×1) or (1×1) after hydrogen exposure, the buckled dimer arrangement seems unlikely to form such $c(4\mathrm{}\times 4)$ periodicity. We propose that Pandey's $\pi$-bonded defect model with small modification might be a possible model of $c(4\mathrm{}\times 4)$ reconstruction in explaining all the observed evidences in our experiment.