Potassium hydroxide treatment of layered WSe 2 with enhanced electronic performances.

2D WSe 2 -based electronic devices have received much research interest. However, it is still a challenge to achieve high electronic performance in WSe 2 -based devices. In this work, we report greatly enhanced performances of different thickness WSe 2 ambipolar transistors and demonstrate homogeneous WSe 2 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 O 2 plasma treatment. Importantly, monolayer WSe 2 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 WSe 2 field-effect transistors exhibit greatly enhanced electronic performance along with the high electron and hole mobilities of 40 and 85 cm 2 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.