Graphene/M₂OS (M = Ga, In) van der Waals Heterostructure with Robust Ohmic Contact

Two-dimensional (2D) Janus semiconductor materials have shown significant potential in the fields of electronics and optoelectronics. The problem of interface contact with electrodes is still faced in the preparation of 2D devices based on them. In this work, we study the interfacial properties of the 2D Janus M2OS (M = Ga, In) material in contact with graphene by using ab initio density functional calculations. The results show that an n-type quasi-Ohmic contact (Ohmic contact) is formed regardless of whether the graphene electrode is in contact with the O or S surface of Ga2OS (In2OS). The heterostructures of graphene and M2OS have a very strong Fermi level pinning effect at the interface due to the gap states and the interface dipole. The layer spacing almost does not affect the contact behavior, which is very advantageous for the preparation of devices. The robust Ohmic contact behavior makes M2OS very competitive in building next-generation nanoelectronic devices.