Electrical and magnetic properties of semimetallic and semiconducting alloys of BiSb

Studies on electrical conductivity, thermoelectric power (t.e.p), Hall effect and diamagnetic susceptibility have been carried out on two inhomogeneous Bi-Sb alloys in the temperature range 100–300 K. Measurements have been confined to the plane perpendicular to the three-fold axis. Antimony impurity levels have been postulated to exist between the bands L_v and L_c. These levels together with the existing band structure of Bi-Sb alloys can explain the observed behaviour of both the alloys of which one is a semimetal and the other a semiconductor. The semiconductor-metal transitions induced by magnetic fields as observed earlier, could also be explained with the help of these antimony levels. The majority of the carriers in both the cases are holes. The different electronic parameters including density of carriers, mobility, nature of the charge carriers and effective masses for all the three bands have been calculated.