Indentation-induced phase transformations in semiconductors

This chapter is concerned with deformation that involves pressure-induced phase transitions. In general, the response of semiconductors to indentation might involve concurrent processes as brittle macro- and micro-fracture, dislocation and defect formation and structural transformations in the material underneath the indenter. A large number of the works have been aimed at understanding the deformation behaviour of silicon (Si) during indentation. However, the influence of phase transformations on the Si response to contact loading was often underestimated due to the difficulties with structural characterization of the thin surface layer affected by the contact interactions. The possibility of phase transformation during indentation of germanium (Ge) was first suggested by I. V. Gridneva et al based on the experimentally determined Germanium hardness as a function of temperature. The plastically extruded layer around indentations is observed more often in Ge than in Si. Raman microspectroscopy analysis of hardness indentations in Ge revealed the formation of different Ge structures depending on the unloading conditions.