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 spec. troscopy. 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.

Automated summary

The interfacial properties of MoS2/4H-SiC heterostructures were studied, and it was found that the valence band offsets increased with increasing MoS2 layer. A strong interlayer interaction was revealed at the 1L MoS2/SiC interface, while Fermi level pinning and surface passivation were achieved at the 4H-SiC (0001) surface. In multilayer MoS2, weak vdW interaction and strong interlayer orbital coupling resulted in type II band alignment and enlarged CBOs and VBOs, while in 1L MoS2/SiC, type I band alignment and asymmetric CBO and VBO were observed.