Transport properties of Bi1-xSbx alloy thin films grown on CdTe(111)B

We have grown Bi1-xSbx alloy thin films on CdTe(lll)B over a wide range of Sb concentrations (0 less than or equal to x less than or equal to 0.183) u sing molecular-beam epitaxy. Temperature-dependent electrical resistivity ( rho) and thermoelectric power (S) were studied. We have observed several di fferences over the bulk system. The 3.5 and 5.1% Sb alloys show semiconduct ing behavior, and the Sb concentration with maximum band gap shifted to a l ower Sb concentration from 15% in bulk to 9%. Based on a simple interpretat ion of the temperature-dependent resistivity the maximum gap would be 40 me V, which is larger than that observed in bulk alloys. In addition, we have observed that the power factor S-2/rho peaks at a significantly higher temp erature (250 K) than previously reported for the bulk alloy (80 K). Differe nces between thin film grown on CdTe(1 1 1) and bulk alloy may arise from t he effects of strain, which is supported by theoretical electronic band cal culations. These results show that BiSb films may be useful as band-enginee red materials in thermoelectric devices. [S0163-1829(99)15315-3].