Energy band alignment of 2D/3D MoS2/4H-SiC heterostructure modulated by multiple interfacial interactions

The interfacial properties of MoS₂/4H-SiC heterostructures were studied by combining first-principles calculations and X-ray photoelectron spectroscopy. Experimental (theoretical) valence band offsets (VBOs) increase from 1.49 (1.46) to 2.19 (2.36) eV with increasing MoS₂ monolayer (1L) up to 4 layers (4L). A strong interlayer interaction was revealed at 1L MoS₂/SiC interface. Fermi level pinning and totally surface passivation were realized for 4H-SiC (0001) surface. About 0.96e per unit cell transferring forms an electric field from SiC to MoS₂. Then, 1L MoS₂/SiC interface exhibits type I band alignment with the asymmetric conduction band offset (CBO) and VBO. For 2L and 4L MoS₂/SiC, Fermi level was just pinning at the lower MoS₂ 1L. The interaction keeps weak vdW interaction between upper and lower MoS₂ layers. They exhibit the type II band alignments and the enlarged CBOs and VBOs, which is attributed to weak vdW interaction and strong interlayer orbital coupling in the multilayer MoS₂. High efficiency of charge separation will emerge due to the asymmetric band alignment and built-in electric field for all the MoS₂/SiC interfaces. The multiple interfacial interactions provide a new modulated perspective for the next-generation electronics and optoelectronics based on the 2D/3D semiconductors heterojunctions.