Defected BN Substrate Induces the Transition from Schottky to Ohmic Contact in Two-Dimensional Metals–Semiconductor Junctions

Although Ohmic contact can be formed in two-dimensional (2D) metal–semiconductor junctions (MSJs) due to the weak Fermi level pinning (FLP) effect, it is inconvenient to prepare different 2D metals matching various semiconductors' work functions well in practice. The weak FLP in 2D MSJs allows their Fermi levels to be easily altered by the impact of the substrate materials. Therefore, utilizing substrates to improve the contact properties of 2D MSJs can be a feasible strategy. Herein, we systematically studied the effect of BN with a B or N vacancy on 2D MSJs. Due to interlayer charge transfer caused by atomic vacancies, the band-edge rigidly shifts, ranging from 0.4 to 1.1 eV. Transmission coefficient and IV curve indicate that the BN substrate indeed induces the transition from Schottky to Ohmic contact. Our work paves the way for the programming of high-performance nanoscale electronic devices.