Structure study of Hg 1− xCd xTe–HgTe superlattice and CdTe/ZnTe/GaAs heterojunctions

Abstract

A rocking curve of Hg 1− x Cd x Te–HgTe superlattice sample grown by molecular beam epitaxy (MBE) was determined by X-ray diffraction around the (0 0 2) Bragg reflection, which shows primarily the superlattice structure property. A simulation curve was calculated using the dynamic theory. There is a good agreement between the two curves, and the period length, HgTe well thickness, and the Hg 1− x Cd x Te barrier thickness measured from the experimental curve is consistent with that calculated from the simulation curve. The CdTe/ZnTe double buffer layers were employed instead of the CdTe single buffer layer. The micrographs of cross-sections of the Hg 1− x Cd x Te–HgTe superlattice and the heterojunctions between the bibuffer layers and substrate were demonstrated by transmission electron microscopy (TEM), and the feature and distribution of mismatch dislocation at the CdTe/ZnTe/GaAs heterojunctions were also analyzed. It is clearly shown that the CdTe/ZnTe double buffer layers are more effective than the single CdTe buffer layer for some defects. The high resolution bright field micrograph of the superlattice cross-section shows the smoothness of the interface, as well as that the average superlattice period length is similar to the one from X-ray diffraction.