Characterization of VGFB-grown ZnTe single crystals by means of synchrotron X-ray topo-tomographic technique

Lattice imperfections in (1 1 1)-oriented ZnTe wafers were characterized by means of X-ray Laue topography using the tomographic technique. The specimens were grown by the vertical gradient freezing Bridgman (VGFB) method. Specimens were set for Bragg diffraction (transmission case) associated with the reciprocal-lattice vector g and were mounted such that they could be rotated around g by means of a rotation stage (ω). White X-ray topographs of the 20-2 spot were taken at rotation angles of ω=0°, ±10°, ±20°, ±30°. We observed a number of twins in spite of the nearly perfect ZnTe crystal with a low dislocation density. The stacking fault energy of ZnTe was found to be lower than for other compound semiconductors.