Tuning of the Thermoelectric Properties of Bi₂Te₃ Nanorods Using Helium Ion Irradiation

The present study reports an enhancement of the power factor of Bi₂Te₃ nanorods NRs) by helium (He⁺) ion irradiation. High-resolution transmission electron microscopy studies revealed the formation of amorphous layers on the surface of the NRs at the high ion fluence. This amorphous nature is due to the accumulation of migrating point defect clusters at the surface of the NRs. Raman scattering experiments provide further insight to the observed structural modifications. At higher ion fluence, impurity-dominated scattering processes significantly enhance the value of the Seebeck coefficient of Bi₂Te₃ NRs. The He⁺ ion irradiation up to the ion fluence of 1 × 10¹⁶ ions/cm² improves the thermoelectric transport properties with the highest power factor, 8.2 μW/m K², at 390 K. Further investigations may result in the possibility of fabricating the Bi₂Te₃ NRs as thermoelectric generators with a high power factor for space applications.