The deformation regimes of the yield point of silicon

Abstract

The upper yield point of undoped floating-zone silicon has been investigated. The measurements were performed on dislocation-free single crystals deformed at temperatures between 800 and 1300°C and a strain-rate range extending over three orders of magnitude. The upper yield point emerges up to 1250°C. In principle, the data reflect the behaviour of the lower yield point, thus confirming the existence of a novel deformation regime of silicon at high temperatures and small strain rates. There are, however, features which resemble the behaviour of highly doped material to some extent. This surprising similarity raises questions concerning the interpretation of the different deformation regimes observed in undoped and doped silicon.