Modulating the Schottky barrier of MXenes/2D SiC contacts functional groups and biaxial strain: a first-principles study.

Two-dimensional (2D) graphene-like SiC has attracted intense interest recently due to its unique electrical and physical properties. In implementing 2D semiconductors in device applications, one of the main challenges so far has been the formation of a high-quality Schottky barrier owing to the strong Fermi level pinning (FLP) at the interface of traditional metal-2D semiconductor contacts. In this paper, the 2D MXenes TiCT (T = F, O, OH) are proposed to serve as electrodes for 2D SiC. The structural and barrier properties of the TiCT/SiC contacts were systematically investigated based on first-principles calculations combined with the GGA-PBE and HSE06 functionals. It is found that TiCT can be bonded with 2D SiC by van der Waals (vdW) interactions. Weak FLP is exhibited at TiCT/SiC vdW contacts. The type of contact can be tuned by changing the functional T group of TiCT. TiCF/SiC and TiCO/SiC contacts exhibit a p-type Schottky contact and p-type Ohmic contact, respectively, whereas an n-type Ohmic contact occurs in the TiC(OH)/SiC contact. In addition, the calculated tunneling possibility () is ∼20% between TiCT and SiC, indicating weak bonding at the TiCT/SiC vdW junctions. Furthermore, the Schottky barrier height and of the TiC(OH)/SiC contacts can be modulated the biaxial strain. The controllable contact type and barrier in TiCT/SiC contacts provide guidelines for developing high-performance 2D SiC optoelectronic and electronic devices.