Semiconductor substrate for growth of an epitaxial semiconductor device

A semiconductor substrate for growth of an epitaxial semiconductor device thereon, said semiconductor substrate comprising:

• a base layer;
• a sacrificial layer formed on said base layer, and including a plurality of spaced apart sacrificial film regions and a plurality of first passages each of which is defined between two adjacent ones of said sacrificial film regions, each of said sacrificial film regions having a plurality of nanostructures and a plurality of second passages defined among said nanostructures, said second passages being communicated spatially with said first passages and having a width less than that of said first passages;
• and
• an epitaxial layer disposed on said sacrificial layer,
• wherein a selective etching ratio of said sacrificial layer to said epitaxial layer is greater than 5;
• and
• wherein said epitaxial layer does not fill said first passages.