TEM Nanosculpting of Topological Insulator Bi$_2$Se$_3$

TL;DR

This paper introduces a TEM-based nanosculpting technique for precise, clean-edged modifications of Bi$_2$Se$_3$ nanoflakes, enabling the creation of complex geometries for topological and thermoelectric applications.

Contribution

It demonstrates a high-resolution TEM method for sculpting Bi$_2$Se$_3$ with sub-10 nm features, preserving crystal structure and offering advantages over ion-beam lithography.

Findings

Achieved sub-10 nm feature sizes with clean edges.

Preserved crystal structure after sculpting.

Potential for improved device fabrication in topological insulators.

Abstract

We present a process for sculpting Bi$_2$Se$_3$ nanoflakes into application-relevant geometries using a high resolution transmission electron microscope. This process takes several minutes to sculpt small areas and can be used to cut the Bi$_2$Se$_3$ into wires and rings, to thin areas of the Bi$_2$Se$_3$, and to drill circular holes and lines. We determined that this method allows for sub 10-nm features and results in clean edges along the drilled regions. Using in-situ high-resolution imaging, selected area diffraction, and atomic force microscopy, we found that this lithography process preserves the crystal structure of Bi$_2$Se$_3$. TEM sculpting is more precise and potentially results in cleaner edges than does ion-beam modification; therefore, the promise of this method for thermoelectric and topological devices calls for further study into the transport properties of such structures.