Zigzag lines in a (001)Si low-angle twist boundary

Abstract

A low angle twist boundary formed by bonding an ultrathin (001) silicon film onto a (001) silicon wafer is investigated using two-beam transmission electron microscopy to identify positively zigzag lines which separate large interfacial regions formed by square networks of 1/2⟨ 110 ⟩ screw misfit dislocations. An approach to the elastic field of a zigzag line is proposed from the repetitive use of angular dislocations added to a ribbon-like uniform distribution of infinitesimal dislocations parallel to a family of pure screw misfit dislocations. Theoretical and experimental images of successive triple nodes are compared to derive the unique set of Burgers vectors attached to a zigzag line. In principle, this approach can be applied to any elongated hexagonal mesh of a dislocation network.