Tribology of Si/SiO2 in humid air: Transition from severe chemical wear to wearless behavior at nanoscale

Lei Chen, Hongtu He, Xiaodong Wang, Seong H. Kim, Linmao Qian

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Wear at sliding interfaces of silicon is a main cause for material loss in nanomanufacturing and device failure in microelectromechanical system (MEMS) applications. However, a comprehensive understanding of the nanoscale wear mechanisms of silicon in ambient conditions is still lacking. Here, we report the chemical wear of single crystalline silicon, a material used for micro/nanoscale devices, in humid air under the contact pressure lower than the material hardness. A transmission electron microscopy (TEM) analysis of the wear track confirmed that the wear of silicon in humid conditions originates from surface reactions without significant subsurface damages such as plastic deformation or fracture. When rubbed with a SiO2 ball, the single crystalline silicon surface exhibited transitions from severe wear in intermediate humidity to nearly wearless states at two opposite extremes: (a) low humidity and high sliding speed conditions and (b) high humidity and low speed conditions. These transitions suggested that at the sliding interfaces of Si/SiO2 at least two different tribochemical reactions play important roles. One would be the formation of a strong "hydrogen bonding bridge" between hydroxyl groups of two sliding interfaces and the other the removal of hydroxyl groups from the SiO2 surface. The experimental data indicated that the dominance of each reaction varies with the ambient humidity and sliding speed.

Original languageEnglish (US)
Pages (from-to)149-156
Number of pages8
Issue number1
StatePublished - Jan 13 2015

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


Dive into the research topics of 'Tribology of Si/SiO2 in humid air: Transition from severe chemical wear to wearless behavior at nanoscale'. Together they form a unique fingerprint.

Cite this