  Strain plays a critical role in the properties of materials. In silicon and
silicon-germanium, strain provides a mechanism for control of both carrier
mobility and band offsets. In materials integra-tion, strain is typically tuned
through the use of dislocations and elemental composition. We demonstrate a
versatile method to control strain, by fabricating membranes in which the final
strain state is controlled by elastic strain sharing, i.e., without the
formation of defects. We grow Si/SiGe layers on a substrate from which they can
be released, forming nanomembranes. X-ray diffraction measurements confirm a
final strain predicted by elasticity theory. The effec-tiveness of elastic
strain to alter electronic properties is demonstrated by low-temperature
longi-tudinal-Hall effect measurements on a strained-Si quantum well before and
after release. Elastic strain sharing and film transfer offers an intriguing
path towards complex, multiple-layer struc-tures in which each layer's
properties are controlled elastically, without the introduction of unde-sirable
defects.
