Impact of Confined Water on the Electronic Structure of the SiO₂ and WS₂ Interface

High Resolution Image Download MS PowerPoint Slide WS 2 /SiO 2 heterostructures are commonly used in the production of field effect transistors, sensors and other devices. It is difficult to remove the water present on the SiO 2 surface during the fabrication process. Using density functional theory simulations, we investigate how confinement between SiO 2 and WS 2 layers affects the water properties and how the presence of water affects the properties of WS 2 film. Using ab initio molecular dynamics simulations we found that the confined water remains mobile but is structured by the interaction with WS 2 and SiO 2 with water protons drawn closer to both surfaces. The presence of 1–3 water layers does not significantly affect the band alignment between SiO 2 and WS 2 and the electronic properties of the WS 2 monolayer. However, in-gap states caused by the dynamic rearrangement of water molecules could cause reduction of electron and hole mobility in the WS 2 layers. This study provides insights into the impact of water on the electronic properties of WS 2 under different environmental conditions.