X-ray observation of twin faults in (1,1,1) CdTe epitaxial layers and in (1,1,1) Hg1−x X xTe/CdTe superlattices

Abstract

This letter describes x-ray precession photographs of (1,1,1) CdTe epitaxial layers on GaAs, CdTe, and Cd0.96Zn0.04Te substrates. The precession method is further applied to some (1,1,1) Hg1−xXxTe/CdTe superlattices where X=Cd or Mn. More than half of the samples used in this study were grown by molecular beam epitaxy, others by metalorganic chemical vapor deposition, and a few by liquid phase epitaxy. The results unambiguously show that the common (1,1,1) face centered cubic twin fault, or stacking disorder, seen in bulk growth methods also exhibits its effects with the mentioned layer deposition growth techniques, except when liquid phase epitaxy is used. It seems that the twinning is intrinsic to the (1,1,1) growth in face centered cubic systems. In addition, devices with twin domains may have lower electronic mobilities. It further means that more experimental work is needed to produce untwinned single-crystal materials deposited by molecular beam techniques.