Growth of Zinc and Cadmium Whiskers from the Vapour Phase on a Single Crystal Substrate of the Same Material

Abstract

A determination is made of the crystallographic orientation of zinc and cadmium whiskers grown on single crystal substrates of the same substances which have well‐formed faces, edges and tips. Zinc and cadmium whiskers grown in this way in the presence of hydrogen or argon are oriented as 〈1120〉, however zinc whiskers grown in vacuum have the orientation 〈1123〉. These are in fact the directions of the screw dislocations in the lattice. These and other results indicate that the whiskers grow preferentially via a screw dislocation mechanism. Some cases are observed in which zinc “whiskers” grow at large supersaturations without involving a surface diffusion mechanism as required by the classical theory of whisker growth. Possible causes for the appearance of whiskers on a single crystal substrate are discussed, as well as the factors which determine their orientation.