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 th
e 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.
The authors describe how acoustic phonons can directly tunnel through vacuum and, therefore, transmit energy and conduct heat between bodies that are separated by a vacuum gap. This effect is enabled by introducing a coupling mechanism, such as piezo
electricity, that strongly couples electric field and lattice deformation. The electric field leaks into the vacuum as an evanescent field, which leads to finite solid-vacuum-solid transmission probability. Due to strong resonances in the system some phonons can go through the vacuum gap with (or close to) unity transmission, which leads to significant thermal conductance and heat flux.
