Electronic properties of (Sb;Bi)2Te3 colloidal heterostructured nanoplates down to the single particle level

Wasim J Mir,Bertille Martinez,Xiang Zhen Xu,Emmanuel Lhuillier,Gilles Patriarche,Hervé Aubin,Nicolas Goubet,Sandrine Ithurria,Alexandre Assouline,Clément Livache

doi:10.1038/s41598-017-09903-w

Abstract

We investigate the potential use of colloidal nanoplates of Sb2Te3 by conducting transport on single particle with in mind their potential use as 3D topological insulator material. We develop a synthetic procedure for the growth of plates with large lateral extension and probe their infrared optical and transport properties. These two properties are used as probe for the determination of the bulk carrier density and agree on a value in the 2–3 × 1019 cm−3 range. Such value is compatible with the metallic side of the Mott criterion which is also confirmed by the weak thermal dependence of the conductance. By investigating the transport at the single particle level we demonstrate that the hole mobility in this system is around 40 cm2V−1s−1. For the bulk material mixing n-type Bi2Te3 with the p-type Sb2Te3 has been a successful way to control the carrier density. Here we apply this approach to the case of colloidally obtained nanoplates by growing a core-shell heterostructure of Sb2Te3/Bi2Te3 and demonstrates a reduction of the carrier density by a factor 2.5.

Highlights

To cite this version: Wasim Mir, Alexandre Assouline, Clément Livache, Bertille Martinez, Nicolas Goubet, et al
By investigating the transport at the single particle level we demonstrate that the hole mobility in this system is around 40 cm2V−1s−1
We develop a colloidal synthesis of Sb2Te3 nanoplates and investigate their transport properties from a thin film down to the single particle level

Summary

Results and Discussion

Transport and optical measurement agree over a bulk hole carrier density in the 2–3 × 1019 cm−3 range We can use this value to determine the position of the Fermi level with respect to the Dirac point: ED − EF. We synthetize a series of (Sb;Bi)2Te3 nanoplates with various Bi content and use the same fitting approach as for the reflectance of the film of Sb2Te3 to determine for each Bi ratio the value of the plasma frequency and the associated carrier density, see Figs 3e and S11, Table S3. The core is made of Bi2Te3, while the shell is made of Sb2Te3 This suggest a higher reactivity of the bismuth compared to antimony towards tellurium, and is consistent with our observation that for similar growth conditions smaller nanoplates of Bi2Te3 are formed. The doping control which has been demonstrated here differs from the approach developed for bulk or thin film in this way that charge compensation occurs at the atomic scale in the heterostructure

Conclusion

Author Contributions

Additional Information