Structural investigations, involving plan-view and cross-sectional transmission electron microscopy (plus etch-pit techniques), were carried out on (¯1¯1¯1)B CdTe epilayers which had been grown onto oriented (¯1¯1¯1)B GaAs substrates by using hot-wall epitaxy. The layers were found to exhibit a complex 3-dimensional twin structure which consisted partly of a series of lamellar twins which extended, from the CdTe/GaAs interface, to a height of about 6 in the epilayer. Above this point, lamellar twinning gave way to a 6-fold pattern of mono-domain sectors having a twin relationship to each other. The sectors were separated from each other by narrow, mixed-domain, boundary regions with radial <110> elongations. The formation of such a twinned structure was explained in terms of an epilayer curvature which was introduced during crystal growth, due to a non-uniform gas-flow distribution. The grain structure in the epilayer was also investigated by using electron diffraction analysis and high-resolution transmission electron microscopy. Although large-angle grain boundaries were found at the interface, a grain re-growth mechanism produced monocrystalline CdTe at the epilayer surface; at least in the mono-domain sectors. Grain boundaries and twin boundaries were found to accumulate in the mixed-domain boundary regions. Also, long dislocation tangles were found in the mixed-domain regions.

A.Hobbs, O.Ueda, Y.Nishijima, H.Ebe, K.Shinohara, I.Umebu: Journal of Crystal Growth, 1993, 126[4], 605-12