High Mobility and Quantum Oscillations in Semiconducting Bi 2 O 2 Te Nanosheets Grown by Chemical Vapor Deposition.

Bi 2 O 2 Te has the smallest effective mass and preferable carrier mobility in the Bi 2 O 2 X (X = S, Se, Te) family. However, compared to the widely explored Bi 2 O 2 Se, the studies on Bi 2 O 2 Te are very rare, probably attributed to the lack of efficient ways to achieve the growth of ultrathin films. Herein, ultrathin Bi 2 O 2 Te crystals were successfully synthesized by a trace amount of O 2 -assisted chemical vapor deposition (CVD) method, enabling the observation of ultrahigh low-temperature Hall mobility of >20 000 cm 2 V -1 s -1 , pronounced Shubnikov-de Haas quantum oscillations, and small effective mass of ∼0.10 m 0 . Furthermore, few nm thick CVD-grown Bi 2 O 2 Te crystals showed high room-temperature Hall mobility (up to 500 cm 2 V -1 s -1 ) both in nonencapsulated and top-gated device configurations and preserved the intrinsic semiconducting behavior with I on / I off ∼ 10 3 at 300 K and >10 6 at 80 K. Our work uncovers the veil of semiconducting Bi 2 O 2 Te with high mobility and brings new blood into Bi 2 O 2 X family.