Potassium hydroxide treatment of layered WSe2 with enhanced electronic performances†

2D WSe₂-based electronic devices have received much research interest. However, it is still a challenge to achieve high electronic performance in WSe₂-based devices. In this work, we report greatly enhanced performances of different thickness WSe₂ ambipolar transistors and demonstrate homogeneous WSe₂ inverter devices, which are obtained by using a semiconductor processing-compatible layer removal technique via chemical removal of the surface top WO_x layer formed by O₂ plasma treatment. Importantly, monolayer WSe₂ was realised after several consecutive removal processes, demonstrating that the single layer removal is accurate and reliable. After subsequent removal of the top layer WO_x by KOH, the fabricated WSe₂ field-effect transistors exhibit greatly enhanced electronic performance along with the high electron and hole mobilities of 40 and 85 cm² V⁻¹ s⁻¹, respectively. Our work demonstrates that the layer removal technique is an efficient route to fabricate high performance 2D material-based electronic devices.