Keywords: GaN films, gallium nitride, Se nanotubes, selenium, nanoindentation, mechanical properties, nanotechnology, penetration depth, tip shape, microstructure, elastic modulus, hardness, deflection points, load–depth curves, load penetration, elastic deformation, plastic deformation
Nanoindentation characterisation of GaN films and Se nanotubes
Mechanical properties of GaN films and Se nanotubes were measured by nanoindentation tests. The GaN films were grown epitaxially on cplane sapphire substrate by MOCVD technique, while Se nanotubes were readily produced by the dismutation of Na2SeSO3. The effect of penetration depth and tip shape on the mechanical properties was studied and discussed according to the elastic–plastic behaviours and features of microstructures. The indenter geometry had a great influence on the elastic modulus and hardness, as well on the characteristic deflection points in the load–depth curves. Meanwhile, the nanoindentation was successfully made by transversely pressing the indenter tip into Se nanotubes. The load–penetration depth curves seemed to be bi–linear, corresponding to the elastic and plastic deformation process. As soon as the penetration depth reached 30 nm, the collapse of Se nanotube occurred.