Elastically strain-sharing nanomembranes: flexible and transferable strained silicon and silicon-germanium alloys

The emerging field of strained-Si based nanomembranes is reviewed, including fabrication techniques, strain-induced band structure engineering, electronic applications and three-dimensional membrane architectures. Elastic strain sharing between thin heteroepitaxial Si and SiGe films, enabled by techniques that allow release of these films from a handling substrate, creates a new material: freestanding, single-crystal, strained nanomembranes. These flexible nanomembranes are virtually dislocation-free and have many potential new applications. Strain engineering also provides opportunities for massively parallel self-assembly of a wide variety of three-dimensional nanostructures.