Plasma-assisted friction control of 2D MoS2made by atomic layer deposition

MoS(2)films as an excellent solid lubricating film can significantly decrease the friction and adhesion of nanoelectromechanical systems. Atomic layer deposition (ALD) as a surface-controlled method provides a flexible way to apply MoS(2)to complex surfaces. In this work, MoS(2)film deposited by ALD on substrates by a plasma-assisted process is used to study controlled friction. Firstly, layer-controlled MoS(2)films were fabricated by ALD from one to five layers. The friction decreases as the number of layers increases. Furthermore, the average friction force of MoS(2)deposited on Al(2)O(3)substrates treated by plasma for 10 s with one ALD cycle has the lowest value. Functional groups on the substrate surface can be obtained by plasma treatment, which can control the growth of the first layer of MoS(2)in ALD so that the frictional characteristics of monolayer MoS(2)can be controlled. Finally, the effect of plasma treatment on ALD growth at the intermediate stage of MoS(2)is relatively weak. Only the monolayer MoS(2)treated by plasma can affect the growth of MoS(2)by ALD. Therefore, the controlling effect of plasma treatment on the frictional characteristics of MoS(2)deposited by ALD mainly occurs at the initial stage of growth.