Inherent Surface Properties of Adsorbent-Free Ultrathin Bi2Se3 Topological Insulator Platelets

Blaž Belec; Katja Ferfolja; Tanja Goršak; Nina Kostevšek; Sandra Gardonio; Mattia Fanetti; Matjaz Valant

doi:10.1038/s41598-019-55646-1

Inherent Surface Properties of Adsorbent-Free Ultrathin Bi₂Se₃ Topological Insulator Platelets

Sci Rep. 2019 Dec 13;9(1):19057. doi: 10.1038/s41598-019-55646-1.

Authors

Blaž Belec¹, Katja Ferfolja², Tanja Goršak^{3

4}, Nina Kostevšek⁵, Sandra Gardonio², Mattia Fanetti², Matjaz Valant^{2

6}

Affiliations

¹ Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia. blaz.belec@ung.si.
² Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia.
³ Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia.
⁴ Jožef Stefan International Postgraduate School, Jamova 39, 1000, Ljubljana, Slovenia.
⁵ Department for Nanostructured Materials, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia.
⁶ Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, 610054, Chengdu, China.

Abstract

We report on a hydrothermal synthesis of hexagonal ultra-thin Bi₂Se₃ platelets, which was performed without any organic reactants. The synthesis resulted in the particles with a surface, clean of any organic adsorbents, which was confirmed with a high-resolution transmission electron microscopy, zeta-potential measurements and thermogravimetric measurements coupled with a mass spectroscopy. Due to the absence of the adsorbed organic layer on the Bi₂Se₃ platelet surface, we were able to measure their inherent surface and optical properties. So far this has not been possible as it has been believed that such hexagonal Bi₂Se₃ platelets can only be prepared by a solvothermal synthesis, for which it was unable to avoid the organic surface layer. Here we explain the mechanism behind the successful hydrothermal synthesis and show a striking difference in zeta potential behaviour and UV-vis absorption characteristics caused by the adsorbed layer. The surface of the hydrothermally synthesized Bi₂Se₃ platelets was so clean to enable the occurrence of the localized surface plasmon resonance due to the bulk and topological surface electronic states.