Optical, Electronic, and Contact Properties of Janus-MoSO/MoS2 Heterojunction

Although oxidization is usually believed to have a negative effect on material performance, oxygen atoms may play a special role in oxidized two-dimensional (2D) transition-metal dichalcogenides (TMDs). In this work, we systematically study the optical, electronic, and contact properties of Janus-MoSO/MoS2 heterojunctions. Our results show that when a MoS2 monolayer becomes a Janus-MoSO monolayer, a vertical intrinsic electric field appears because of the discrepancy of electronegativity between S and O atoms. If this oxidation process takes place in a bilayer MoS2, an asymmetric heterojunction is formed. Janus-MoSO/MoS2 shows type-II band alignment with an extremely small exciton binding energy, which facilitates the photoinduced electron and hole separation. In addition, when the electrode Au contacts with the bilayer MoS2, a Schottky barrier is usually observed, whereas this barrier vanishes when Au contacts with Janus-MoSO/MoS2, thus improving the device performance. We believe that the proposed structure based on Janus-MoSO may significantly improve the performance of TMD materials, which thereby guide the designing of two-dimensional nanodevices.