(311) FACETS OF SELECTIVELY GROWN EPITAXIAL SI LAYERS ON SIO2-PATTERNED SI(100) SURFACES

A Si epitaxial layer was selectively grown on SiO2-patterned Si(100) w ith no miscut and on 1-degrees, 3-degrees, and 4-degrees miscut vicina l surfaces by ultrahigh-vacuum chemical-vapor deposition using disilan e. On the patterned Si(100) surfaces with and without miscuts, faceted (100) layers grew. Although {111} is energetically the most stable su rface, the resulting facets had {311} orientation. This means that the {311} faceting is related to the growth kinetics rather than the ener getics. Macroscopically, the {311} faceting is caused by the slower gr owth rate of the (31 1) surface than that of the (100) surface. On the vicinal surfaces, the top surface of the selectively grown layer was not vicinal but had exactly (100) orientation. This indicates the read y incorporation of adatoms into the step edges of (100) terraces and t he subsequent step-flow growth mode. When the flowing step reaches the end of the top surface, it is swallowed into the facet and disappears . This decreases the step density and makes the vicinal surface flat. With respect to the swallowing of the growing steps at the facet corne r, we propose a microscopic model for the {311} faceting.