Vapour growth and defect characterisation of large single crystals of ZnS and Zn(Se, Se)

Abstract

Crystals of ZnS have been grown from the vapour phase by two different methods. In the first, a technique, which is essentially a modification of that used by Piper and Polich [1], has been developed to grow crystals at temperatures in the region of 1600°C. In the second, which is a method employing a sealed evacuated capsule, the ZnS is transported down a temperature gradient to crystallise below the phase transition temperature of 1020°C. By using these two methods it was hoped to produce crystalline ZnS in predominantly the wurtzite or zinc blende phase. Examination in the transmission electron microscope has shown that the crystals grown at the higher temperature contain the larger proportion of stacking disorder and comprise a mixture of phases and polytopes, while those grown at the lower temperature are largely cubic with much less stacking disorder. Suggestions are offered to account for these observations, and the results of preliminary investigations into the application of the high temperature method to the growth of mixed crystals of Zn(S, Se) are described.