SYNCHROTRON WHITE-BEAM X-RAY TOPOGRAPHY ANALYSIS OF MBE GROWN CDTE CDTE (111)B/

The structural quality of CdTe (111)B substrates and MBE grown CdTe ep ilayers is examined with synchrotron white beam x-ray topography (SWBX T). Reflection SWBXT indicates that CdTe substrates with comparable x- ray double crystal rocking curve full width at half maximum values can have radically different defect microstructures, i.e. dislocation den sities and the presence of inclusions. Dislocation mosaic structures d elineated by SWBXT are consistent with the distribution of etch pits r evealed by destructive chemical etch pit analysis. Direct one-to-one c orrespondence between distinct features of the topographic image and i ndividual etch pits is demonstrated. Clearly resolved images of indivi dual dislocations are obtained by carrying out transmission SWBXT. Our investigation demonstrates how the extent of twinning in a CdTe epila yer is strongly influenced by the quality of the defect microstructure , and how dislocations propagate from an inclusion.