Nanomechanical resonators realized from tensile-strained
materials
reach ultralow mechanical dissipation in the kHz to MHz frequency
range. Tensile-strained crystalline materials that are compatible
with epitaxial growth of heterostructures would thereby at the same
time allow realizing monolithic free-space optomechanical devices,
which benefit from stability, ultrasmall mode volumes, and scalability.
In our work, we demonstrate nanomechanical string and trampoline resonators
made from tensile-strained InGaP, which is a crystalline material
that is epitaxially grown on an AlGaAs heterostructure. We characterize
the mechanical properties of suspended InGaP nanostrings, such as
anisotropic stress, yield strength, and intrinsic quality factor.
We find that the latter degrades over time. We reach mechanical quality
factors surpassing 107at room temperature with aQ·fproduct as high as 7 × 1011Hz with trampoline-shaped resonators. The trampoline is patterned
with a photonic crystal to engineer its out-of-plane reflectivity,
desired for efficient signal transduction of mechanical motion to
light.