Kinetics of selective epitaxial growth of Si and relaxed Ge by ultrahigh vacuum chemical vapor deposition in Si(001) windows

Relaxed germanium was deposited following a low temperature-high temperature procedure by ultrahigh vacuum chemical vapor deposition in Si trenches opened through a SiO2 mask. The resulting growth is selective, the germanium fills the Si trenches and evolves towards a roof-shaped morphology limited by (001), {113} and {111} facets. The evolution in height of the Ge structure depends on the trench width, and can be understood by considering a growth rate in the < 113 > direction equal to 22% of that measured along the < 001 > axis. At last, a surprisingly strong Ge diffusion under the SiO2 mask was revealed by selective chemical etching. Such a phenomenon was unexpected because no diffusion through the Si/Ge interface was previously observed on plain wafer. (C) 2006 Elsevier Ltd. All rights reserved.