Thermoelectric properties of n-type Bi–Te thin films with various compositions

Bismuth–telluride-based materials have excellent room-temperature thermoelectric properties. In this study, the composition of Bi–Te thin films deposited by RF-magnetron sputtering was systematically varied across a single wafer. X-ray diffraction, field emission-scanning electron microscopy (FE-SEM, JEOL, JSM-7000F) and energy dispersive X-ray spectroscopy (EDS) were then used to investigate the thermoelectric properties of the Bi–Te films as a function of the Te fraction. The Te content of the films ranged from 38% to 81%, and their microstructure and crystal structure varied depending on the Te content. The Seebeck coefficients of the Bi–Te thin films were in the range −10 to 153 μV/K, and the maximum power factor of the films was 3.7 × 10−4 W/K2 m, without post annealing.