Mechanical behaviour characterisation of silicon and effect of loading rate on pop-in: A nanoindentation study under ultra-low loads

This paper aims to clarify the confusion in interpreting the deformation mechanism of monocrystalline silicon subjected to nanoindentation. The indentation tests were carried out over an ultra-low range of loads with various loading rates using a Berkovich indenter. It was found that with a proper area function of the indenter tip the mechanical properties of silicon can be accurately characterised, that a pop-in event may occur upon ultra-low loading and represents the onset of phase transition, and that a lower loading rate favors a sudden volume change but a rapid loading process tends to generate a gradual slope change of the load–displacement curve.