Anomalously high thermoelectric figure of merit in Bi1-xSbx nanowires by carrier pocket alignment

Electronic transport calculations were carried out for Bi1-xSbx nanowires (0 less than or equal tox less than or equal to0.30) of diameters 10 nm less than or equal tod(W)less than or equal to 100 nm at 77 K. A band structure phase diagram was generated, showing the dependence of the relative band edge positions on diameter and composition. Calculations of the thermoelectric figure-of-merit (ZT) predict that the performance of Bi1-xSbx nanowires is superior to that of Bi nanowires and to that of the bulk alloy. An exceptionally high value of ZT for p-type nanowires at 77 K was found for d(W)similar to 40 nm and x similar to0.13, which is explained by the coalescence in energy of up to ten valence subband edges to maximize the density-of-states at the Fermi energy. (C) 2001 American Institute of Physics.