Fascinating Electrical Transport Behavior of Topological Insulator Bi2 Te3 Nanorods: Toward Electrically Responsive Smart Materials

Electrical conductivity and dielectric parameters are general inherent features of materials. Controlling these characteristics through applied bias will add a new dimension to regulate the dynamic response of smart materials. Here, a fascinating electrical transport behavior is observed in topological insulator (TI) Bi₂ Te₃ nanorods, which will play a vital role in intelligent materials or devices as a unit for information reception, processing or feedback. The Bi₂ Te₃ nanorod aggregates exhibit a monotonic resistance response to voltage, with observed four-fold change of electrical conductivity in a small range electric field of 1 V mm^-1 . The dielectric constant and dielectric loss of Bi₂ Te₃ nanorod composites also show strong dependences on bias voltage due to the unique electrical transport characteristics. The unique voltage-controlled electrical responses are attributed to the change of Fermi levels within the band structure of disordered TI nanorods, which are non-parallel to the applied electric field. The excellent controllable inherent characteristics through electric field endows Bi₂ Te₃ nanomaterials bright prospects for applications in smart devices and resistive random access memories.

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.