Artificially ordered BiSb alloys: growth and transport properties

Abstract

We propose a new approach for potentially achieving high-ZT materials: artificially ordered alloy structures. We have prepared artificially ordered Bi/Sb alloys with different (Bi/Sb) periods from 7.7 /spl Aring/ to 55 /spl Aring/ by MBE. Atomic-scale ordering effects on the structural and transport properties have been studied. The formation of an ordered alloy was confirmed by the presence of XRD superlattice satellites. Using electrical resistivity, thermopower, and magneto-transport measurements, we have observed a semimetal-semiconductor transition in an ordered BiSb superlattice. The intentional ordering of the layered Bi-Sb structure has produced a new phase and the measured differences in the electronic spectrum relative to the random alloy are a consequence of its atomic structure.