Twinning in vapour-grown, large volume Cd1−xZnxTe crystals

• Twinning in vapour-grown bulk Cd1−xZnxTe characterised by X-ray diffraction imaging.
• Twinning is not associated with strains at the GaAs/CdTe interface.
• Twinning is not related to lattice strains associated with injection of Zn.
• Un-twinned material remained after twinning.
• Twin boundaries are sub-micron in scale.

The onset of twinning from (2¯1¯1¯) to (1¯3¯3¯) in large volume Cd1−xZnx  Te crystals, grown by vapour transport on (2¯1¯1¯), often referred to as (211)B, oriented GaAs seeds, has been investigated using X-ray diffraction imaging (X-ray topography). Twinning is not associated with strains at the GaAs/CdTe interface as the initial growth was always in (2¯1¯1¯) orientation. Nor is twinning related to lattice strains associated with injection of Zn subsequent to initial nucleation and growth of pure CdTe as in both cases twinning occurred after growth of several mm length of Cd1−xZnxTe. While in both cases examined, there was a region of disturbed growth prior to the twinning transition, in neither crystal does this strain appear to have nucleated the twinning process. In both cases, un-twinned material remained after twinning was observed, the scale of the resulting twin boundaries being sub-micron. Simultaneous twinning across the whole sample surface was observed in one sample, whereas in the other, twinning was nucleated at different points and times in the growth.