Strong piezoelectricity in individual GaN nanowires

GaN nanowires are promising building blocks for future nanoelectronics, optoelectronic devices, and nanogenerators. Here, we report on strong piezoelectricity in individual single-crystal GaN nanowires revealed by direct measurement of the piezoelectric constant using piezoresponse force microscopy. Our experimental results show that individual c-axis GaN nanowires, with a characteristic dimension as small as 65 nm, show a shear piezoelectric constant of d₁₅ ~ 10 pm/V, which is several times that measured in bulk. The revealed strong piezoelectricity could open promising opportunities for application of GaN nanowires in nanowire-based sensors and generators for self-powered nanodevices.