Thermoelectric Properties of Bismuth-Doped Tin Telluride SnTe:Bi

Abstract

The recent discovery of excellent thermoelectric properties and topological surface states in SnTe-based compounds has attracted extensive attention in various research areas. Indium doped SnTe is of particular interest because, depending on the doping level, it can either generate resonant states in the bulk valence band leading to enhanced thermoelectric properties, or induce superconductivity that coexists with topological states. Here we report on the vapor deposition of In-doped SnTe nanowires and the study of their surface oxidation and thermoelectric properties. The nanowire growth is assisted by Au catalysts, and their morphologies vary as a function of substrate position and temperature. Transmission electron microscopy characterization reveals the formation of amorphous surface in single crystalline nanowires. X-ray photoelectron spectroscopy studies suggest that the nanowire surface is composed of In 2 O 3 , SnO 2 , Te and TeO 2 which can be readily removed by argon ion sputtering. Exposure of the cleaned nanowires to atmosphere yields rapid oxidation of the surface within only one minute. Characterizations of electrical conductivity σ, thermopower S, and thermal conductivity κ were performed on the same In-doped nanowire which shows suppressed σ and κ but enhanced S yielding an improved thermoelectric figure of merit ZT than the undoped SnTe. 2

Enhanced thermoelectric properties of hydrothermally synthesized Bi0.88−xZnxSb0.12 nanoalloys below the semiconductor–semimetal transition temperature

“…This is associated with a smaller effective ionic radius of Zn 2+ (0.74Å for coordination number ¼ 6) than that of Bi 3+ (1.03Å for coordination number ¼ 6). 36,37 The relative bulk density of Bi 0.88Àx Zn x Sb 0.12 alloys falls between 94-99% and 95-99% of the theoretical density for samples sintered at 170 C and 250 C, respectively ( Table 1). The porosity of Bi 0.88Àx Zn x Sb 0.12 alloys seems to decrease with increasing Zn content based on the density measurements.…”