Helical dislocations and spiral etch-pits

Abstract

Abstract The etch-patterns due to helical dislocations are discussed. It is suggested that under certain conditions the etching of a helical dislocation gives rise to a spiral etch-pit of the kind observed on germanium and silicon crystals. Etch-patterns on (111) faces of fluorite crystals containing helical dislocations can readily be interpreted on the same basis.