Direct real-time observation on nanoscale mechanical behavior of freestanding GaN short nano-bridge

This paper describes a novel technique to design, fabricate, test, and real-time monitor the freestanding GaN nano-bridge over homogeneous substrate. Stress–strain response and Young’s modulus of GaN nano-bridge for 1.2 μm in span with aspect ratio of ~5 can be extracted by observing mechanical load–deflection response video images and load–displacement curve using instrumented nanoindentation in transmission electron microscopy. A two-dimensional finite element model showed that a positive agreement between principal stresses varies in a beam by experimental observation and stress contour versus indentation depth by numerical simulation. This method could also be applied on the wide range of nano-materials to identify the mechanical response.