Electronic and optical properties of two-dimensional MoSi2N4/SiC heterojunction: First-principles study

This study employs first-principles calculation to investigate the MoSi2N4/SiC heterojunction. It aims to determine the structure, electronic, and optical properties of the heterojunction and assess the impact of varying vertical electric fields and biaxial strains on these properties. The results show that the MoSi2N4/SiC heterojunction is a direct bandgap semiconductor, exhibiting a band gap of 0.31 eV. This heterojunction benefits from a built-in electric field originating from the SiC layer and extending to the MoSi2N4 layer. The optical absorption peaks in the ultraviolet region are significantly more intense than those in MoSi2N4 and SiC monolayers, particularly at a wavelength of 172 nm, where the intensity reaches 1.99 × 106 cm−1. The study also shows that an increasing positive vertical electric field leads to a rising band gap. On the other hand, increasing tensile or compressive strain causes a gradual decline in the band gap. Specifically, at a strain of −8%, the absorption peak intensity reaches 3.4 × 106 cm−1 at 172 nm, and the absorption spectrum broadens to 722 nm at an 8 % strain. In conclusion, the MoSi2N4/SiC heterojunction shows promise for enhancing the optical properties of two-dimensional materials and offers valuable insights for the development of efficient new ultraviolet devices.