The characterization of an Si(001)-c(4 × 4) structure formed using monomethylsilane

At the initial stage of 3C-SiC growth on Si(001) using a organosilicon compound such as monomethylsilane (MMS), Si(001)-c(4 × 4) was formed before the nucleation of SiC islands. From observation of the c(4 × 4) structure by scanning tunnelling microscopy (STM), it was found that both c(4 × 4) domains and (2 × 1) domains coexisted. From the estimation of the lattice size for these structures by line profile measurement, the lattice size of the c(4 × 4) domain was contracted and that of the (2 × 1) domain was expanded. Therefore, the c(4 × 4) domain was considered to be the preferential nucleation site of SiC. The STM observation for the c(4 × 4) structure formed using MMS also revealed that the c(4 × 4) domain consisted of both the α-cell and the β-cell, similar to that formed by silicon deposition and subsequent sample annealing. An STM image of an α-cell, however, did not show a central spot in the empty state. So, the top dimer of the α-cell is not an Si–Si dimer but another dimer.