Crystallography and elasticity of individual GaN nanotubes

Abstract

High-purity, crystalline [001]-oriented GaN nanotubes with outer diameters of 200 nm or more, rough surfacesand irregular internal channels were synthesized under epitaxial growth on[001]-oriented sapphire substrates. Elastic property measurements on free-standingindividual GaN nanotubes, using the in situ transmission electron microscopy (TEM)electromechanical resonance technique, pointed at an average Young’s modulusE of 37 GPa and minimum quality factor of 320. These numbers are notably lower thanthose for previously reported GaN nanowires. The crystallography and chemistryof the GaN nanotubes were analyzed using TEM and energy dispersion x-rayspectroscopy (EDS). It is suggested that the lowered Young’s modulus and qualityfactor of the nanotubes are mainly due to the surface roughness and defectiveness.