Investigation of strained Si/SiGe-OI heterostructure with high resolution electron microscope

Observations on cross-sectional microstructure of Si/SiGe-OI grown by ultra-high vacuum chemical vapor deposition are done with an electron microscope with high resolution for investigating relaxation mechanism of strain induced by misfit. The cross-sectional image of Si/SiGe-OI multi-layer structure,the lattice image of every epitaxial layer, and the interfaces of adjoining epitaxial layers are shown respectively. 60° dislocations and stacking faults distributed in the multi-layer structure are found. Some related theories are applied to explain the configuration of the defects. The reasons are discussed about formation and existing of 60° misfit dislocations using critical thickness model developed by Matthews and Blakeslee and other related investigations. The theoretical conclusion predicted by Gosling and his co-workers is proved reliable that single misfit dislocations generally lie in the interface between strained Si1-xGex layer and Si substrate for a heterostructure with a capping layer thinner than its critical thickness.