Wednesday, 31 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
Bismuth telluride(BiTe) is known as a promising material for thermoelectric devices. In this study, we fabricated BiTe thin films by using electrodeposition method and investigated the composional variation depending on the process parameters such as electrolyte composition, plating potential and thermal annealing temperatures. We prepared working electrodes by coating 50 nm of Au on P-type Si(100) wafers using electron-beam deposition method. The plating electrolyte was composed of Bi(NO3)3-5H2O, TeO2 and HNO3, where the concentration of Bi and Te ions varied from 1 mM to 30 mM. Electroplating was carried out with a potentiostatic method with the plating potential from –0.15 V to 0.1 V. As we changed the plating potential, we could observe that the relative contents of Bi and Te in the thin films could be adjusted in a continuous manner and that thin films changed from N-type to P-type semiconductor. The thin films were annealed by RTA with the annealing temperature between 220 and 260oC and the annealing time between 1 and 120 min. By annealing the films, the grain size of BiTe increased from 40 nm to 90 nm and the electrical resistivity increased from 2 uΩ·m to 8 uΩ·m. Maximum electromotive force was –1005 μV and highest power factor was 8.3 mW/m·K2.