Dislocation Reduction by Glide in Epitaxial IV–VI Layers on Si Substrates

It is explained with a simple model why the reduction of threading dislocation (TD) densities in epitaxial lattice and thermal expansion mismatched IV–VI layers such as PbSe(111) on Si(111) substrates follows a 1/h2 dependence where h is the thickness of the layer. This is in contrast to the 1/h dependence for III–V and II–VI layers grown on mismatched substrates. The 1/h2 dependence results since the thermal mismatch strain is mainly reduced by glide and reactions of the TD in their main {100}-type glide system of the NaCl-type IV–VI semiconductors. In addition, multiple thermal cycles lead to further reduction of the TD densities by glide and fusion since fusion does not cause dislocation blocking.