Transport properties of Bi12xSbx alloy thin films grown on CdTe„111...B

We have grown Bi12xSbx alloy thin films on CdTe(111)B over a wide range of Sb concentrations (0<x <0.183) using molecular-beam epitaxy. Temperature-dependent electrical resistivity ~r! and thermoelectric power ~S! were studied. We have observed several differences over the bulk system. The 3.5 and 5.1% Sb alloys show semiconducting behavior, and the Sb concentration with maximum band gap shifted to a lower Sb concentration from 15% in bulk to 9%. Based on a simple interpretation of the temperature-dependent resistivity the maximum gap would be 40 meV, which is larger than that observed in bulk alloys. In addition, we have observed that the power factor S/r peaks at a significantly higher temperature ~250 K! than previously reported for the bulk alloy ~80 K!. Differences between thin film grown on CdTe~111! and bulk alloy may arise from the effects of strain, which is supported by theoretical electronic band calculations. These results show that BiSb films may be useful as band-engineered materials in thermoelectric devices. @S0163-1829~99!15315-3#