  We report on fabrication and characterization of ultra-thin suspended single
crystalline flat silicon membranes with thickness down to 6 nm. We have
developed a method to control the strain in the membranes by adding a strain
compensating frame on the silicon membrane perimeter to avoid buckling of the
released membranes. We show that by changing the properties of the frame the
strain of the membrane can be tuned in controlled manner. Consequently, both
the mechanical properties and the band structure can be engineered and the
resulting membranes provide a unique laboratory to study low-dimensional
electronic, photonic and phononic phenomena.
