Improved Gas Sensing Capabilities of MoS₂/Diamond Heterostructures at Room Temperature

Molybdenum disulfide (MoS2) and nanocrystallinediamond(NCD) have attracted considerable attention due to their unique electronicstructure and extraordinary physical and chemical properties in manyapplications, including sensor devices in gas sensing applications.Combining MoS2 and H-terminated NCD (H-NCD) in a heterostructuredesign can improve the sensing performance due to their mutual advantages.In this study, the synthesis of MoS2 and H-NCD thin films using appropriate physical/chemicaldeposition methods and their analysis in terms of gas sensing propertiesin their individual and combined forms are demonstrated. The sensitivityand time domain characteristics of the sensors were investigated forthree gases: oxidizing NO2, reducing NH3, andneutral synthetic air. It was observed that the MoS2/H-NCD heterostructure-based gas sensor exhibitsimproved sensitivity to oxidizing NO2 (0.157%& BULL;ppm(-1)) and reducing NH3 (0.188%& BULL;ppm(-1)) gases compared to pure active materials (pure MoS2 achieves responses of 0.018%& BULL;ppm(-1) for NO2 and -0.0072%& BULL;ppm(-1) for NH3, respectively, and almost no response for pure H-NCD at roomtemperature). Different gas interaction model pathways were developedto describe the current flow mechanism through the sensing area with/withoutthe heterostructure. The gas interaction model independently considersthe influence of each material (chemisorption for MoS2 andsurface doping mechanism for H-NCD) as well as the current flow mechanismthrough the formed P-N heterojunction.