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 II-VI quaternary alloy Zn0.5Cd0.5Se0.5Te0.5. Samples were grown by molecular beam epitaxy on (100) GaAs substrates, 4 degree miscut towards 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 for a random arrangement. The results imply the formation of high-strain local structure and indicate that electronic pairing energies dominate over strain energy. These results are similar to the earlier observation of interlayer switching in ZnTe/CdSe superlattices. The preference of Zn-Se and Cd-Te bonding also implies a tendency to spontaneously form a composition-modulated microstructure. copyright 1997 The American Physical Society