Atomic rearrangement at ZnTe/CdSe interfaces.

Abstract

X-ray-absorption fine-structure spectroscopy and x-ray diffraction have been used to study the local atomic structure of four different short-period ZnTe/CdSe (001) superlattices grown by molecular-beam epitaxy. The data indicate Zn-Se and Cd-Te coordination numbers greater than those expected for sharp interfaces in the superlattice. Although strain would appear to suppress interdiffusion, it is shown that the results are consistent with an interchange of the Zn and Cd atomic planes across the Zn-Se interface and Se and Te atomic planes across the Cd-Te interface. Theoretically, this switch of atomic planes has been shown to be energetically favorable by comparing the changes in chemical bond-formation energies and strain energies between a perfect superlattice and one with the above-mentioned switching of atomic planes. Accommodation of this strain is shown through bond bending and bond stretching at the newly formed interfaces.