Semimetal-semiconductor Transitions in Bismuth-antimony Films and Nanowires Induced by Size Quantization

CZU 539.261.1 

In this paper we present the experimental results of an investigation of the electrical transport, thermoelectrical properties, the Shubnikov de Haas oscillations of Bi_1-xSb_x films (0 < x < 0.04) grown by the vacuum thermal evaporation and nanowires prepared by a modified Ulitovsky – Teilor technique. The results of the X-ray diffraction indicate that the trigonal axes were perpendicular to the film plane and the single Bi-2at%Sb nanowires with the diameter 100–1000 nm were represented by single crystals in a glass capillary with (1011) orientation along the wire axis. The investigations of the Shubnikov de Haas oscillations on Bi-2at%Sb wires with d > 600 nm show that overlapping of L and T bands was twice smaller than that in pure Bi. The temperature dependences of thin semimetalic Bi-3at%Sb films and Bi-2at%Sb wires show a semiconducting behavior. The semimetal-semiconductor transition induced by the quantum confinement effect is observed in semimetal Bi_1-xSb_x films and nanowires at the diameters up to five times greater than those in the pure Bi. That experimental fact, on the one hand, will allow observing the display quantum confinement effect at higher temperatures on nanowires of the same diameters, and, on the other hand, will allows separating effects connected with the surface state and the quantum size effects. In addition, the thermoelectric properties and thermoelectric efficiency of bismuth-antimony wires are considered and a possibility to use them in thermoelectric converters of energy is discussed.

Keywords: nanowires, films, semimetal-semiconductor transition, size quantization, thermoelectricity.