On transition temperatures in the plasticity and fracture of semiconductors

Recent experiments on deformation of semiconductors show an abrupt change in the variation in the critical resolved shear stress τY with temperature T. This implies a change in the deformation mechanism at a critical temperature T c. In the cases examined so far in our laboratories (Case Western Reserve University and Poitiers) and elsewhere, this critical temperature appears to coincide approximately with the brittle-to-ductile transition temperature T BDT. In this paper, new deformation experiments performed on the wide-bandgap semiconductor 4H-SiC over a range of temperatures at two strain rates are described together with a transmission electron microscopy characterization of induced dislocations below and above T c. Based on these, and results recently reported on a few III–V compound semiconductors, a new model for the deformation of tetrahedrally coordinated materials at low and high temperatures is proposed, and the relation of the transition in deformation mode to the transition in fracture mode (brittle to ductile) is discussed.