An HREM study of the defects in ZnS

Abstract

High-resolution electron microscopy (HREM) has been used to investigate the defect structures in ZnS crystals of zincblende type with 〈110〉 beam incidence. It is concluded that there is a high density of 180° rotation twins. Under different imaging conditions the bright dots in the HREM micrographs may either correspond to the atomic column pairs or the structural channels surrounded by atoms, and these make the twin boundary appear in different forms by changing experimental parameters. End-on extended dislocations which are formed by the dissociation of 60° mixed dislocation and 0° screw dislocation with Burgers vectors of 1/2〈110〉 type were analysed and characterized Using anisotropic elasticity theory of dislocations and the width of dissociation measured from HREM images, the stacking fault energy on the {111} plane in ZnS has been determined to be 2·7±0·1 mJm⁻². Frank dislocations located at the twin boundary and a Hirth dislocation lock having a Burgers vector of the 1/6〈002〉 type are also discussed.