Coplanar High Mobility and Interplanar Van Der Waals Heterojunction in Layered Two-Dimensional Bi₂O₂Se Nanosheets

In this letter, the electronic transport features of layered two-dimensional (2D) Bi ₂ O ₂ Se semiconductor nanosheets are characterized along the in-plane and the out-of-plane directions, respectively. The modulation of double gate is manufactured on a 26.4 nm CVD-grown Bi ₂ O ₂ Se-nanosheet MOSFET, thus executing the highest in-plane field-effect mobility of ~296 cm ² V ^-1 s ^-1 at room temperature. Furthermore, the rectification behavior of charge transport across the perpendicular interlayer of Bi ₂ O ₂ Se nanosheet is distinctly scrutinized. Correspondingly, the existing of potential barrier between the [Bi ₂ O ₂ ] ²ⁿ⁺ and [Se] ^2n- interlayers of Bi ₂ O ₂ Se nanosheets is validated by the temperature-dependent current measurement and the Poole-Frenkel model. This work offers promising routes to implement high-efficient field-effect transports parallel to the in-plane direction, as well as tunable heterojunction transports across the perpendicular interlayer of 2D Bi ₂ O ₂ Se nanosheets.