MoS2 Transistor with Weak Fermi Level Pinning via MXene Contacts

The quality of the contact between source/drain electrodes and 2D transition metal dichalcogenides (TMDs) plays a decisive role in improving transistor performance. Understanding the mechanisms of Fermi level pinning (FLP) and finding out the strategies to solve FLP problems can further promote the development of 2D electronics. In this work, the suppressing effect of MXene on FLP in MoS2 transistors by using Ti3C2Tx as an electrode to build a Ti3C2Tx-MoS2 heterostructure is systematically studied. A simple and time-saving ultraviolet ozone technique to tune the work function of the Ti3C2Tx electrode in the range of 4.33-5.32 eV is proposed, and a low Schottky barrier height of 121 meV is achieved. The van der Waals contact between Ti3C2Tx and MoS2 can alleviate the FLP effectively, and the pinning factor can be greatly optimized from 0.28 (metal electrode) to 0.87 (MXene electrode). This work can pave the way for extensive use of MXene and provide a new strategy to eliminate the negative effects of FLP in 2D materials-based electronic devices.