Metal semiconductor contact behavior between MXene Ti3C2T2 (T = bare, F, O, or OH) and two-dimensional GaN

Detailed first-principles calculations are performed to investigate the metal-semiconductor contact behavior between Ti₃C₂T₂ (T = bare, F, O, or OH) and GaN monolayer. We reveal that Schottky barrier heights in Ti₃C₂T₂/GaN metal semiconductor junctions are deviated from the Schottky–Mott limit. This is attributed to the interface dipole induced potential step that modifies the intrinsic work function of Ti₃C₂T₂. High-quality n-type Ohmic contact with superior tunneling probability could be realized in N-top stacking Ti₃C₂/GaN and Ti₃C₂OH₂/GaN, indicating the potential application of Ti₃C₂ and Ti₃C₂OH₂ as gate contact metal suitable for 2D GaN-based channel with a high efficiency of carrier injection. Meanwhile, p-type quasi-Ohmic contact could be achieved in Ga-top stacking Ti₃C₂F₂/GaN and Ti₃C₂O₂/GaN but with high tunneling barrier. Our work not only sheds light on the fundamental contact properties of 2D metal/GaN interfaces, but also provides electrode material selection for 2D GaN, which helps give theoretical guidance for developing high-performance 2D GaN-based (opto)electronic devices.