Phase Transformation of Silicon under Nonhydrostatic Stress State: Formation of Si II Phase under a Round Indenter

Abstract

Silicon transforms from a diamond cubic structure to a β-Sn structure as induced by mechanical stress, the magnitude of which changes depending on the stress state. In this study, the origin of the transformed silicon is explored with a stress criterion independent of the stress state. As an illustration of a nonhydrostatic stress state, the stress distribution of silicon under a round indenter is analyzed by finite element analysis. As a result, the initial formation of β-Sn structured silicon is successfully explained using the new stress criterion.