Tear Marks on Cleaved Germanium Surfaces

Abstract

A microscopic study has been made of the origin and nature of tear marks in germanium. The observations suggest that the tear marks can originate in two different ways. The majority are thought to occur when the crack attains a critical velocity, the lattice disturbances set up ahead of the advancing crack deflecting the crack onto different levels. The second type is formed when the curvature of the fracture surface changes abruptly. Taper sections show that the steps at both types of tear mark are identical in profile; they are generally perpendicular to the cleavage surface but frequently contain curved segments.