Abstract: The effect of sliding velocity on the wear behavior of monocrystalline silicon under various contact size is studied by nanoscratch and servo hydraulic dynamic test machine. It is found that both the contact size and sliding velocity played significant roles in the friction-induced surface damage of silicon. When the contact size is small enough to be considered as single-asperity contact, the surface damage of silicon exhibited the formation of hillock under low load. With the increase in the sliding velocity, the friction-induced amorphous layer became thinner and the height of hillock is lower. As the contact pressure increased above the hardness of silicon, the surface damage of silicon is identified as the generation of groove. The higher of the sliding velocity, the stronger the work-hardening of the contact area, and the shallower the groove. As a comparison, when the contact size is large enough to be considered as multi-asperity contact, the silicon surface may be worn even though the contact pressure is much lower than the hardness of silicon. During the wear process, both plough, fatigue and oxidation wear occurre simultaneously. With the increase in the sliding velocity, more cracks are initiated, tinier wear debris is generated, and less wear volume is observed. The results may not only help the improvement of the nanofabrication technique of silicon, but also optimize the tribological design of microelectromechanical system.

Key words: Contact size, Monocrystalline silicon, Sliding velocity, Wear behavior