Temperature dependence of point contact friction on silicon

Point contact friction and adhesion between a silicon tip and an untreated silicon(111) wafer are measured as a function of sample temperature in ultrahigh vacuum by friction force microscopy. While the friction coefficient changes drastically in the temperature range from 50 K to room temperature, and shows a reproducible maximum near 100 K, the simultaneously recorded adhesion shows much less temperature dependence. Interestingly, the velocity dependence of friction shows a logarithmic increase below 150 K although it is nearly constant above 150 K. This peculiar behavior has profound consequences for tribological properties of devices manufactured from silicon. (c) 2006 American Institute of Physics.