Controlled p-Type Doping of MoS₂ Monolayer by Copper Chloride

Electronic devices based on two-dimensional (2D) MoS₂ show great promise as future building blocks in electronic circuits due to their outstanding electrical, optical, and mechanical properties. Despite the high importance of doping of these 2D materials for designing field-effect transistors (FETs) and logic circuits, a simple and controllable doping methodology still needs to be developed in order to tailor their device properties. Here, we found a simple and effective chemical doping strategy for MoS₂ monolayers using CuCl₂ solution. The CuCl₂ solution was simply spin-coated on MoS₂ with different concentrations under ambient conditions for effectively p-doping the MoS₂ monolayers. This was systematically analyzed using various spectroscopic measurements using Raman, photoluminescence, and X-ray photoelectron and electrical measurements by observing the change in transfer and output characteristics of MoS₂ FETs before and after CuCl₂ doping, showing effective p-type doping behaviors as observed through the shift of threshold voltages (Vth) and reducing the ON and OFF current level. Our results open the possibility of providing effective and simple doping strategies for 2D materials and other nanomaterials without causing any detrimental damage.