High resolution electron microscopy study of molecular beam epitaxy grown CoSi2/Si1−xGex/Si(100) heterostructures

Abstract

Two CoSi2/Si1−xGex/Si(100) heterostructures, with different Ge content, made by molecular beam epitaxy are characterized by high resolution electron microscopy. In general, the interface between the CoSi2 thin film and the Si1−xGex layer is of a high structural quality and the strained Si1−xGex layer exhibits few defects. For both samples, different interface structures are present, although the dominant interfacial configuration is similar to the unreconstructed interface present at the CoSi2/Si(100) interface. Only occasionally (2×1) reconstructed interface regions are found which are just a few nanometers in length. Phenomena such as Ge segregation and the introduction of defects are also observed in the Si1−xGex layer. We attribute the minimal presence of the reconstructed interface to both the (2×8): Si1−xGex(100) surface reconstruction and the Ge segregation that takes place.