Modulation of contact type in BAs/Hf3C2 heterostructure via surface functionalization and strain

The exploration of contact property is greatly vital to improve the performance of transistors based on two-dimensional (2D) materials. In this work, we construct 2D BAs/Hf3C2 vdW heterostructure to explore its contact property based on first-principles calculations. We find that the BAs layer shows metallic feature in the BAs/Hf3C2 heterostructure, suggesting Hf3C2 destroys the band dispersion of BAs due to the appearance of strong interfacial coupling. Therefore, the pristine Hf3C2 is not ideal electrode material. The functionalization of Hf3C2 can weaken the interlayer interaction and make BAs maintain its semiconductor feature. Here, we select chalcogens and halogens to functionalize the Hf3C2, forming Hf3C2X2 (X = O, S, Se, Te, F, Cl, Br, and I). Furthermore, we investigate the contact type, Schottky barrier, charge transfer, and tunneling probability of BAs/Hf3C2X2 heterostructures. Ohmic contact is formed in the most BAs/Hf3C2X2 systems, suggesting that they possess high performance with a view to the application for the transistors. The biaxial strain and external electric field are utilized to modulate the contact type and barrier height in the BAs/Hf3C2O2 and BAs/ Hf3C2F2 heterostructures.