Identifying the Manipulation of Individual Atomic-Scale Defects for Boosting Thermoelectric Performances in Artificially Controlled Bi2Te3 Films

The manipulation of individual intrinsic point defects is crucial for boosting the thermoelectric performances of n-Bi2Te3-based thermoelectric films, but was not achieved in previous studies. In this work, we realize the independent manipulation of Te vacancies VTe and antisite defects of TeBi and BiTe in molecular beam epitaxially grown n-Bi2Te3 films, which is directly monitored by a scanning tunneling microscope. By virtue of introducing dominant TeBi antisites, the n-Bi2Te3 film can achieve the state-of-the-art thermoelectric power factor of 5.05 mW m(-1) K-2, significantly superior to films containing VTe and BiTe as dominant defects. Angle-resolved photoemission spectroscopy and systematic transport studies have revealed two detrimental effects regarding VTe and BiTe, which have not been discovered before: (1) The presence of BiTe antisites leads to a reduction of the carrier effective mass in the conduction band; and (2) the intrinsic transformation of VTe to BiTe during the film growth results in a built-in electric field along the film thickness direction and thus is not beneficial for the carrier mobility. This research is instructive for further engineering defects and optimizing electronic transport properties of n-Bi2Te3 and other technologically important thermoelectric materials.

Automated summary

This study achieved independent manipulation of Te vacancies and antisite defects in n-Bi2Te3 films, leading to the discovery of the crucial role of TeBi antisites in enhancing the thermoelectric power factor. Angle-resolved photoemission spectroscopy and transport studies revealed previously unknown detrimental effects of BiTe antisites and VTe to BiTe transformations on electronic transport properties.