Stress control of tensile-strained In <sub/>1?</sub><sub/><i>x</i> </sub> Ga <sub/><i>x</i> </sub> P nanomechanical string resonators

摘要： We investigate the mechanical properties of freely suspended nanostrings fabricated from tensile-stressed, crystalline In1?xGaxP. The intrinsic strain arises during epitaxial growth as a consequence of the lattice mismatch between the thin film and the substrate, and is confirmed by x-ray diffraction measurements. The flexural eigenfrequencies of the nanomechanical string resonators reveal an orientation dependent stress with a maximum value of 650 MPa. The angular dependence is explained by a combination of anisotropic Young’s modulus and a change of elastic properties caused by defects. As a function of the crystal orientation, a stress variation of up to 50% is observed. This enables fine tuning of the tensile stress for any given Ga content x, which implies interesting prospects for the study of high Q nanomechanical systems.