Analysis of a wafer bonded $Ge∕Si$ heterojunction by transmission electron microscopy

A wafer-bonded $Ge∕Si$ heterojunction was observed using transmission electron microscopy to analyze its crystallographic properties and to reveal atomic profiles at the interface by energy dispersive x-ray spectroscopy. There was a $2nm$ thick transition layer at the heterojunction, where an aligned lattice image from Si to Ge together with a disordered lattice image could be observed. In the Si layer close to the interface, islandlike modified regions were observed to exist, where a large amount of Ge was detected. Oxygen was also detected accumulated at the interface.