A Note on the Unloading Behavior of Silicon Subjected to Nanoindentation

It is known that silicon, during nanoindentation unloading, undergoes various phase transformations beneath the indenter. Investigations into the details are however not available. This paper studies the unloading behavior of silicon subjected to cyclic nanoindentations. The results show that the elastic unloading behavior of the material can be described by a power relationship, P = α∙hm, where P is the load, h is the elastic displacement, and α and m are material constants. It was found that the values of α and m were almost independent of the phase transition events, indicating that the elastic response of the material is mostly governed by the mechanical properties of Si-I phase while the influence of the phase transformations is negligible.