INITIAL PROCESS OF SI HOMOEPITAXIAL GROWTH ON SI(001)

Initial growth processes of Si on the Si(001) surface are investigated by studying the stability of various ad-Si clusters and calculating e nergy barriers for some fundamental processes by using a first-princip les method. An ad-Si perpendicular dimer on top of a substrate dimer r ow is formed easily and is the most stable among dimers, consistent wi th experiment. The dimer can be a diffusing unit at high temperatures but cannot be a nucleus for dimer row growth at lower temperatures. On the other hand, a quasistable parallel dimer in a trough attracts mon omers and can be the nucleus of a diluted-dimer row.