Growth of the Bi₂Se₃ Surface Oxide for Metal–Semiconductor–Metal Device Applications

The effect of the surface structure of Bi₂Se₃ on its interior properties has been well studied recently, but the interfacial structure and electrical properties of the oxidized Bi₂Se₃ surface are little known. In contrast to the self-limited formation of native oxide on Bi₂Se₃, the degree of oxidation on the Bi₂Se₃ surface in oxygen plasma is enhanced. Results of transmission electron microscopy and X-ray photoelectron spectroscopy show that the surface of the oxidized Bi₂Se₃ is composed of a layer of amorphous bismuth oxide (BiO_<i>x</i>), and the thickness of the BiO_<i>x</i> layer can be controlled by the length of the plasma process. Electrical measurements of this structure present the Schottky-type transport property at the interface between the oxidized layer and the bulk Bi₂Se₃ crystal, and the turn-on voltage depends on the thickness of the surface BiO_<i>x</i> layer. This study of the structure, formation mechanism, and electrical properties of the surface oxide of Bi₂Se₃ formed in oxygen plasma provides useful information for future development of electronic devices based on bismuth chalcogenides