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 m0. 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 Ion/Ioff ∼ 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.