Growth Processes in Si/Si(111) Epitaxy Observed by Scanning Tunneling Microscopy during Epitaxy

We have studied Si/Si(111) epitaxy during the growth process at high temperatures (500--900 K) with the scanning tunneling microscope. During the growth of two-dimensional islands, we observe three different growth processes: initial sharpening of the corners of triangular Si(111) islands, nucleation in the second layer at domain boundaries of the (7×7) reconstruction, and growth at the island edges occurring along rows of the width of the (7×7) unit cell. During the coalescence of islands, we observe the development of a new [112̄] facet growing with high growth speed. A model of hindered nucleation on the faulted part of the (7×7) reconstruction explains the experimental results.