Effect of Magnetic Doping on Electrical and Thermal Conductivities and Seebeck Coefficient of Suspended Bismuth Telluride Nanoplates

Bismuth telluride has been investigated intensively as a model system for topological insulators. In this work, we have studied electrical and thermal transport properties of suspended bismuth telluride nanoplates grown by the vapor-solid method. The thin crystals were transferred onto micro-fabricated suspended structures with built-in electrodes and thermometers, which allowed us to measure electrical ($\sigma )$ and thermal ($\kappa )$ conductivities as well as the Seebeck coefficient ($S)$. The through-etched hole in the devices enabled us to evaporate Cr layers on both surfaces of the crystal. After H$_{2}$ annealing at 500 K, we measured enhanced $\sigma $, $\kappa $, and $S$ values by 40, 10, and 20{\%}, respectively. In comparison, H$_{2}$ annealing without Cr evaporation resulted in 10, 10, and -8{\%} changes of $\sigma $, $\kappa $, and $S$ values, respectively. The effect of magnetic doping by Cr will be discussed. Additionally, magneto-transport measurements were performed on the samples to resolve the transport properties of the surface states. We observed a pronounced weak anti-localization feature in undoped samples. Changes in this feature after Cr doping will be presented.