Observation of Size and Irradiation Effects on Thermal and Electrical Properties of Bi-Sb-Te Nanowire
Chia Hua Chien1,2,3*, Ping Chung Lee2, Wei Han Tsai2, Chih Hao Lee1, Yang-Yuan Chen2
1Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan
2Institute of Physics, Academia Sinica, Taipei, Taiwan
3Nano Science and Technology Program, Taiwan International Graduate Program, National Tsing Hua University and Academia Sinica, Taipei, Taiwan
* presenting author:Chia Hua Chien, email:chien750410@gate.sinica.edu.tw
The electrical and thermal conductivities of a single Bi2-xSbxTe3-y nanowire (NW) were studied at room temperature as it was trimmed down from 750 to 490 and 285 nm in diameter by Ga ions bombardment. Although both electrical and thermal conductivity indubitably decrease with the diameter reduction, the two properties clearly exhibit different diameter dependence. For 750 and 490 nm NWs, the drastic decrease of thermal conductivity (0.72 and 0.69 W/m-K respectively) was distinctly seen as compared with the bulk (2.22 W/m-K) but no similar result was seen in electrical conductivity, this consequence implies the phonon scattering is much more sensitive than that of electron in this diameter region. As the wire was further trimmed down to 285 nm, both the electrical and thermal conductivity exhibited a dramatic (about 74 %) drop due to crystalline-amorphous phase and defect formation induced by Ga ions implantation. This study provides a possible method to manipulate the electrical and thermal conductivity of NWs via Ga ions irradiation in order to modulate the thermoelectric performance of nanostructures for applications.

Keywords: nanowire, thermal conductivity, electrical conductivity, thermoelectric properties