Scanning probe microscopy induced surface modifications of the topological insulator Bi₂Te₃ in different environments

We investigated the topological insulator (TI) Bi₂Te₃ 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 Bi₂Te₃ is observed to be strongly modified during SPM measurements, while imaging of freshly cleaved Bi₂Te₃ in UHV and nitrogen gas shows considerably less changes of the Bi₂Te₃ surface. We conclude that the reduced surface stability upon exposure to ambient conditions is triggered by adsorption of molecular species from ambient, including H₂O, CO₂, etc which is verified by Auger electron spectroscopy. Our findings of the drastic impact of exposure to ambient on the Bi₂Te₃ surface are crucial for further in-depth studies of the intrinsic properties of the TI Bi₂Te₃ and for potential applications that include room temperature TI based devices operated under ambient conditions.