溅射MoS_2膜的特征形态及摩擦变化IntroductionMolybdenum disulfide (MoS2) has emerged as a promising material for various applications due to its unique electronic, optical and mechanical properties. Among them, the thin-film MoS2 has become an important research target due to its outstanding properties of high transparency, flexibility and chemical stability. However, the adhesion and friction properties of MoS2 films are still in the early stage of investigation. In this work, we study the characteristic morphology of sputtered MoS2 films and their frictional behavior under different environmental conditions.Experimental ProceduresThe MoS2 thin films were deposited on a silicon wafer substrate using a magnetron sputtering technique, under an Ar gas pressure of 310-3 Torr and a substrate temperature of 300 C. The thickness of the films was approximately 100 nm. The films were then characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to analyze their surface morphology and topography. The friction properties of the films were evaluated using a microtribometer by measuring the coefficient of friction (COF) under different environmental conditions, including dry nitrogen, air, and water vapor.Results and DiscussionThe SEM images showed that the MoS2 films exhibited a uniform surface morphology with a slight roughness, indicating a good adhesion to the substrate. The AFM images revealed that the films had a smooth surface with a root-mean-square (RMS) roughness of 0.67 nm, which was attributed to the crystal structure of MoS2. The topography of the films showed a layered structure consisting of parallel ridges and trenches, which was consistent with the hexagonal structure of the MoS2 crystal.The COF measurements showed that the frictional behavior of the MoS2 films was strongly dependent on the environmental conditions. In dry nitrogen, the COF was relatively low, around 0.06, which can be attributed to the formation of an ultra-thin boundary lubrication film on the surface of the films. Under air and water vapor environments, the COF increased to around 0.12 and 0.22, respectively. This increase can be attributed to the adsorption of water vapor molecules on the surface of the films, which leads to a decrease in the contact area and an increase in the interfacial adhesion.ConclusionIn this work, we investigated the characteristic morphology of sputtered MoS2 thin films and their frictional behavior under different environmental conditions. The MoS2 films exhibited a uniform surface morphology with a layered structure consisting of ridges and trenches. The films showed good adhesion behavior and the COF was strongly dependent on the environmental conditions. This study can provide valuable insights into the adhesion and frictional behavior of MoS2 films for potential applications in various fields, such as microelectromechanical systems and nanotribology.Furthermore, the adhesion and friction properties of MoS2 films are related to their thickness and crystal orientation. It has been reported that thinner MoS2 films have better adhesion and lower friction compared to thicker films due to the decreased thickness of the lubrication layer. Additionally, the crystal orientation of the MoS2 film can also affect its frictional behavior. It has been observed that the basal plane of the MoS2 crystal shows lower friction than the edge plane due to its lower surface energy and weaker interlayer interaction.In terms of practical applications, MoS2 films have shown promising results for their use as a solid lubricant in microelectromechanical systems (MEMS) and nanotribology. The low-friction properties of MoS2 films can reduce wear and prolong the lifespan of MEMS devices. Additionally, MoS2 films can also be used as protective coatings for metals and alloys, as they can provide improved wear resistance and corrosion protection.In conclusion, the adhesion and frictional behavior of MoS2 films are essential characteristics to consider for their potential applications. This study provides insights into understanding the surface morphology, topography, and frictional behavior of sputtered MoS2 films under different environmental conditions, which can be beneficial for further research and practical applications.Furthermore, the lubricating behavior of MoS2 films is also influenced by their surface chemistry and topography. The surface chemistry of MoS2 films can be altered through surface modifications such as surface functionalization or doping with other elements, which can affect their adhesion and friction properties. Moreover, the topography of MoS2 films such as roughness and morphology can also significantly affect their lubricating behavior. For example, MoS2 films with a high aspect ratio can exhibit excellent lubrication properties due to their ability to form anisotropic grooves that act as effective lubrication pockets.MoS2 films can also be combi