Structural defects in ZnGeP2single crystals revealed by X-ray topography

Abstract

The results of X-ray transmission topography and diffraction analysis of a ZnGeP2single crystal grown by the vertical Bridgman method in the [001] direction are presented and discussed. The FWHM of rocking curves over a large area of a (100) longitudinal slice is about 12′′, which is indicative of the high quality of the examined sample. Glow discharge mass spectrometry does not show significant content of foreign chemical elements. X-ray topography reveals growth striations and dislocations. The predominant defects are single dislocations and their pile-ups. Near to the growth-axis region, curved dislocation bundles passing through the entire crystal are observed, on which precipitates are formed. In the initial part of the crystal, dislocations are located chaotically, while towards the middle of the sample they are aligned along the growth striae. In the final part of the crystal, the dislocation density increases.