Scanning probe microscopy induced surface modifications of the topological insulator Bi₂Te₃in different environments

Abstract

We investigated the topological insulator (TI) BiTe in four different environments (ambient, ultra-high vacuum (UHV), nitrogen gas and organic solvent environment) using scanning probe microscopy (SPM) techniques. Upon prolonged exposure to ambient conditions and organic solvent environments the cleaved surface of the pristine BiTe is observed to be strongly modified during SPM measurements, while imaging of freshly cleaved BiTe in UHV and nitrogen gas shows considerably less changes of the BiTe surface. We conclude that the reduced surface stability upon exposure to ambient conditions is triggered by adsorption of molecular species from ambient, including HO, CO, etc which is verified by Auger electron spectroscopy. Our findings of the drastic impact of exposure to ambient on the BiTe surface are crucial for further in-depth studies of the intrinsic properties of the TI BiTe and for potential applications that include room temperature TI based devices operated under ambient conditions.

Structural and electronic properties of the pure and stable elemental 3D topological Dirac semimetal α-Sn

“…Combined with the previous reports on the enhanced temperature stability of strained α-Sn films (up to 170 • C) 2,45,46 , our findings give this material an additional application value. Having the reports on the fragile air-stability of the more widely investigated 3D topological materials Bi 2 Te 3 [47][48][49] and Bi 2 Se 3 50,51 (caused by adsorption of molecular species from ambient), this finding could make α-Sn more favorable for applications.…”

Nanoscopic diffusion of water on a topological insulator

“…On the one hand, Bi 2 Se 3 reacts with water vapour giving rise to an n-doping of the surface 23 . In the case of Bi 2 Te 3 on the other hand, it was shown that water adsorption is less pronounced than the adsorption of oxygen 26,36 , even though the reactivity of water with Bi 2 Te 3 is still under debate 26,27,37 . Except for the influence of adsorbates on the electronic structure, chemistry on TI surfaces has been largely ignored, even though it was shown that TIs hold great potential for sensing applications 38,39 and exfoliation in liquid environment has been used to obtain nanosheets with unique properties [40][41][42] .…”

Electrochemical Scanning Tunneling Microscopy Study of Bismuth Chalcogenide Single Crystals

“…It is possible that the electric field between the sample and the tip enhances the dissolution process. Previously, Netsou et al observed the tip-induced modification of a Bi 2 Te 3 surface that had been exposed to ambient conditions, 27 though these experiments were not carried out under electrochemical control.…”

“…Netsou et al compared Bi 2 Te 3 in UHV, nitrogen, ambient, and organic solvent environments. 27 The surface stability was much less in the latter two, with clear evidence of surface modification during STM scans. Compared to earlier studies, the novelty in this work lies in our studying controlled oxidation under electrochemical control, rather than uncontrolled exposure to air/water.…”

“…In this study, only the top QL reacted with water. Netsou et al compared Bi 2 Te 3 in UHV, nitrogen, ambient, and organic solvent environments . The surface stability was much less in the latter two, with clear evidence of surface modification during STM scans.…”