Interface-blocking mechanism for reduction of threading dislocations in SiGe and Ge epitaxial layers on Si(100) substrates

Abstract

A mechanism of interface blocking was proposed to reduce the threading dislocations in the SiGe and Ge layers on Si(100) substrates. In this work, epitaxial Si1−xGex∕Si1−(x−y)Gex−y and Ge∕SiyGe1−y layers were grown by UHV/CVD. It was surprisingly found that if the variation of the Ge composition, y, across the interface of Si1−xGex∕Si1−(x−y)Gex−y or Ge∕SiyGe1−y is higher than a certain value, most of the threading dislocations appear to be blocked and confined in the underlying Si1−(x−y)Gex−y or SiyGe1−y layer by the interface. It implies that this finding can provide a simple way to grow high-quality relaxed SiGe and Ge layers on the Si substrates.