The first-principles study on the halogen-doped graphene/MoS2 heterojunction

• Published in: Solid state communications 2021-08, Vol.334-335, p.114366, Article 114366
• Main Authors: Fu, Siyao, Wang, Dawei, Ma, Zhuang, Liu, Guotan, Zhu, Xiaoshuo, Yan, Mufu, Fu, Yudong
• Format: Article
• Language: English
• Subjects: Electronic structures; Graphene/MoS2 heterojunction; Halogen doping; Optical properties
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2021.114366

Monolayer graphene has a zero band gap, and monolayer MoS2 has a direct band gap of 1.80 eV. In the form of van der Waals heterostructure, the combination can open the Dirac point of graphene. In this paper, the graphene/MoS2 heterojunctions were doped with the elements of F, Cl, Br and I to construct four systems. The defect formation energies, electronic structures and optical properties of four doped systems were calculated based on the first-principles. According to the defect formation energies, S vacancy became the best choice of doping site. The band structures of the doped heterojunctions changed significantly and appeared new energy levels. In addition, the MoS2 layers in the four heterojunctions produced some density of states near the Fermi surface. By calculating the optical properties that are the dielectric functions of the four halogen-doped graphene/MoS2 heterojunctions, the optical absorption range of the halogen-doped heterojunctions expanded from the visible light range to the infrared light range. This phenomenon indicates that the doping of halogen in the graphene/MoS2 heterojunction can expand the light absorption range of the heterojunction and improve the utilization rate of the heterojunction to infrared light. This work focuses on the optical modification of graphene/MoS2 heterojunction. The heterojunctions were regulated by means of doping halogens. The electronic structures and optical properties were calculated to investigate the influence of doping halogens in heterojunctions.•In this paper, three defects of graphene/MoS2 heterojunction are designed, namely, S vacancy, Mo vacancy and C vacancy. By calculating the formation energy of vacancy and that of four halogens doped into three different vacancies, the lowest formation energy of halogen doped at S atomic site on the heterojunction surface is obtained.•The doping system changes the band structure of the conduction band minimum, so that the dielectric peak appears near the infrared light.•Compared with the density of states of the four doping systems, there is little difference in the density of states of C atom in each system, which is mainly reflected in MoS2. In addition, the difference in density of states near Fermi surface is the reason for the difference in band structure.•The doping systems have a luminous effect in the infrared light range. Among four halogens, I element doping has the most significant effect on the optical modification of heterojunction.