Flexible Germanium Nanowires: Ideal Strength, Room Temperature Plasticity, and Bendable Semiconductor Fabric

The mechanical strengths of individual germanium (Ge) nanowires with ⟨111⟩ growth direction and diameters ranging from 23 to 97 nm were measured by bending each with a robotic nanomanipulator in a scanning electron microscope (SEM). The nanowires tolerate diameter-dependent flexural strains of up to 17% prior to fracture, which is more than 2 orders of magnitude higher than bulk Ge. The corresponding bending strength of 18 GPa is in agreement with the ideal strength of 14−20 GPa for a perfect Ge crystal. Nanowires also exhibited plastic deformation at room temperature, becoming amorphous at the point of maximum strain. A bendable, nonwoven fabric, or paper, of Ge nanowires is demonstrated.