Synthesis and Characterization of High-T_c Superconducting Oxides by the Modified Citrate Gel Process

Abstract

The ZnTe/CdSe superlattice is one of the wide-gap semiconductor superlattices grown successfully in recent years which have potential applications in blue-green diode lasers. There exists experimental evidence of interchange of entire atom layers across the interfaces of ZnTe/CdSe superlattices in spite of the resulting interface strain. First-principles pseudopotential calculations of the total energy of such systems confirmed the possibility of such interchanges. By using the combination of a first-principles pseudopotential method and an empirical method with parameters extracted from the available experimental data and pseudopotential calculations, we studied phonons in ZnTe/CdSe superlattices with interchange of atom layers across the interface. The results are compared with phonons in ZnTe/CdSe superlattices with ideal interfaces. Several unique features of phonon modes in superlattices with interchange of atomic layers across interfaces are identified and discussed. These results provide more information about interface structures in such heterostructures, and we hope that they will stimulate more experimental measurements in these materials. § Permanent address:

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