Improvement of Thermoelectric Properties in (Bi0.5Sb0.5)(2)Te-3 Films of Nanolayered Pillar Arrays

摘要

In this work, it is found that unique pillar arrays with nanolayered structure can favorably influence the carrier and phonon transport properties of films. p-(Bi0.5Sb0.5)(2)Te-3 pillar array film with (0 1 5) orientation was successfully achieved by a simple ion-beam-assisted technique at deposition temperature of 400A degrees C, owing to the enhanced mobility of deposited atoms for more sufficient growth along the in-plane direction. The pillar diameter was about 250 nm, and the layered nanostructure was clear, with each layer in the pillar array being < 30 nm. The properties of the oriented (Bi0.5Sb0.5)(2)Te-3 pillar array were greatly enhanced in comparison with those of ordinary polycrystalline films synthesized at deposition temperature of 350A degrees C and 250A degrees C. The (Bi0.5Sb0.5)(2)Te-3 pillar array film with (0 1 5) preferred orientation exhibited a thermoelectric dimensionless figure of merit of ZT = 1.25 at room temperature. The unique pillar array with nanolayered structure is the main reason for the observed improvement in the properties of the (Bi0.5Sb0.5)(2)Te-3 film.