X-RAY STUDY OF ATOMIC CORRELATIONS IN ZN0.5CD0.5SE0.5TE0.5 EPITAXIAL THIN-FILMS

X-ray absorption fine-structure spectroscopy (XAFS) measurements have been performed at approximately 90 K to study the local structure of I I-VI quaternary alloy Zn0.5Cd0.5Se0.5Te0.5. Samples were grown by mole cular beam epitaxy on (100) CaAs substrates, 4 degrees miscut rewards the (111)B direction with a ZnTe buffer layer. The XAFS data indicate that there are more Zn-Se and Cd-Te bonds in the alloy than expected f or a random arrangement. The results imply the formation of high-strai n local structure and indicate that electronic pairing energies domina te over strain energy. Theses results are similar to the earlier obser vation of interlayer switching in ZnTe/CdSe superlattices. The prefere nce of Zn-Se and Cd-Te bonding also implies a tendency to spontaneousl y form a composition-modulated microstructure.