Probabilistic Analysis of Site-Occupation Preferences in GaxIn1-xAsySb1-y and Cd1-xMnxSeyTe1-y Quaternary Compounds

B.V. Robouch Guest, Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, CP.65, 00044 Frascati(RM), Italy and A. Kisiel Instytut Fizyki, Uniwersytet Jagielloński, Reymonta 4, 30-059 Kraków, Poland

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Site-occupation preferences in quaternary GaInAsSb and CdMnSeTe compounds in tetrahedrally coordinated zinc-blende structures are discussed. Probabilistic eigenfunctions are defined to determine individual component pair-populations from measured average-pair distributions. The methodology and possible traps in interpreting site-occupation preferences of published EXAFS experimental overall average-pair distributions are discussed. The approach allows a deeper understanding of individual pair selective preferences in semiconducting multinary compounds. EXAFS reported departures from Bernoulli random distributions point to changes within elemental tetrahedral average-populations. Resolution requires that for tetrahedral structures experimental data best-fit be a 4th degree polynomial, product of a parabola by the factor x(1-x). The analysis shows that both materials have a marked preference for elemental tetrahedra with odd numbers of competing species of ions around a central ion.

DOI: 10.12693/APhysPolA.94.497 PACS numbers: 63.90.+t