An ultra-high Q silicon compound cantilever resonator for Young's modulus measurements

We describe the design of ultra-high Q mechanical cantilever resonators, fabricated from single-crystal silicon wafers. The mechanical resonance mode at f ≈ 8.5 kHz achieves a background damping of Q−1 ≲ 2 × 10−8 at temperatures below 30 K, which is equal to that of a successful silicon torsional resonator with which the cantilever resonator shares several design elements. The new resonator can be used for accurate measurements of the Young's modulus and internal friction of thin films. It is compatible with both the mounting apparatus and measurement electronics of the torsional resonator, and the two resonators together can be used to provide a complete description of the elastic properties of isotropic thin films.