First-principles investigations on MXene-blue phosphorene and MXene-MoS₂ transistors

In the semiconductor industry, one of the most important steps in the development of electronic devices is the discovery of electrode materials that are suitable for ohmic contact. As a newly found type of 2D materials, MXenes have been explored as materials for use in field effect transistors (FETs) with promising performances, which urges for the underlying mechanisms to be understood. In this work, the behaviors of the 5-10 nm device models for monolayer blue phosphorene (BlueP) and MoS₂ with a MXene electrode are investigated using ab initio quantum transport simulations. Firstly, the interfacial properties of BlueP and MoS₂ in contact with M₃C₂T₂ (M = Ti, Zr, or Hf; T = F, OH, or O) MXene are studied. The results show that OH and some of the F functionalized MXenes form an n-type ohmic contact with BlueP or MoS₂, while the O functionalized MXenes form a p-type ohmic contact with BlueP and MoS₂. Accordingly, when the FET model is built with M₃C₂(OH)₂ electrodes, these FETs exhibit high on-currents due to the ohmic contacts with subthreshold swing between 100 ∼ 200 mV/decade, and high on/off ratios up to 10⁶ at a bias voltage of 0.5 V. Our results imply that a FET with a sub-10 nm channel length can satisfy the requirements of both high performance and low power logic applications. The results from this study indicate that MXenes may act as the appropriate electrode for high-performance BlueP and MoS₂ FETs, which may provide new clues to guide the application of various 2D materials in electronics.