High Mobility and Quantum Oscillations in Semiconducting Bi₂O₂Te Nanosheets Grown by Chemical Vapor Deposition

Abstract

Bi₂O₂Te has the smallest effective mass and preferable carrier mobility in the Bi₂O₂X (X = S, Se, Te) family. However, compared to the widely explored Bi₂O₂Se, the studies on Bi₂O₂Te are very rare, probably attributed to the lack of efficient ways to achieve the growth of ultrathin films. Herein, ultrathin Bi₂O₂Te crystals were successfully synthesized by a trace amount of O₂-assisted chemical vapor deposition (CVD) method, enabling the observation of ultrahigh low-temperature Hall mobility of >20 000 cm² V^-1 s^-1, pronounced Shubnikov-de Haas quantum oscillations, and small effective mass of ∼0.10 <i>m</i>₀. Furthermore, few nm thick CVD-grown Bi₂O₂Te crystals showed high room-temperature Hall mobility (up to 500 cm² V^-1 s^-1) both in nonencapsulated and top-gated device configurations and preserved the intrinsic semiconducting behavior with <i>I</i>_on/<i>I</i>_off ∼ 10³ at 300 K and >10⁶ at 80 K. Our work uncovers the veil of semiconducting Bi₂O₂Te with high mobility and brings new blood into Bi₂O₂X family.