CLUSTER-ORDERED ARRAY ON THE SI(001) SURFACE FORMED BY AL DEPOSITION

Local phases formed by Al deposition on Si(001) at an elevated temperature have been observed using ultrahigh-vacuum scanning tunneling microscopy. These phases, c(4×12), c(4×16), c(4×22), and c(4×24), and so on, are established above 0.5 ML of Al at 500°C, and attributed to the formation of Al or an Al-Si cluster-ordered array. The sizes and heights of these clusters are very regular and they are remarkably ordered in the [110] or [110] direction. On the other hand, the initial stages below 0.5 ML of Al show complicated changes of the surface structures, such as cluster formation, terrace etching, and trench formation. These phenomena are probably caused by an Al-Si reaction at an elevated temperature. © 1995 The American Physical Society.