UC Riverside

Transition metal dichalcogenides (TMDs) are novel materials that possess a direct band-gap when deposited at a single layer thickness. These 2D materials offer properties that set them apart from conventional bulk silicon such as an improved on-off ratio and the potential for photonic application, with the indirect bandgap of silicon being the limit. If implemented commercially, the former will reduce the power consumption of, e.g., memory devices, significantly, while the latter opens up new pathways for on-chip integration of emitter and detectors for optical communication. Continuing miniaturization of semiconducting devices require the incorporation of materials such as these. We have developed a method that allows deposition of MoS2 films across large surface areas in high vacuum and at precise thickness control. The chamber was designed to achieve high vacuum at 10-7 torr with the goal of maintaining a clean interface during deposition of the material. MoS2 single-layer films offer an improved on-off ratio for transistor devices leading to lower power consumption in the off state as compared to silicon. The high vacuum nature of this system eliminates concern for contaminants that may result from being in ambient pressures. This allows for creating a cleaner interface for better functioning electronics such as diodes. We look to incorporate this material with the III-V semiconductor, gallium nitride, as a way to manipulate the band structure in processes unique to this reactor. These MoS2 films can also render gold nanoparticles stable and active for carbon monoxide oxidation and higher alcohol formation even on otherwise inert substrates. Previously, this activity of gold had only been observed on reducible bulk oxides like titania and ceria. This method’s ability to coat industrial glass surfaces for this application may reduce costs and allow the transition from current platinum catalysts to much “cheaper” gold ones. This research effort may both help in building more energy-efficient microchips and in creating green fuels by higher alcohol formation from biomass gasification and further strengthens homogenous deposition of MoS2.