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.