Shivalik: We have been working on silicon and related materials concerning friction and adhesion for a couple of years. Since there was no commercial friction tester available, we built one (see bottom for URL). I assume that you are dealing with forces in the micro newton range. If this is so you have to expect electrostatic forces and after proper grounding stong capillary forces. It is therefore hard to say, which value friction has. We measured the friction force in air as well as in UHV and learned that the value drops as the pressure in the chamber decreases. This is caused by the desorption of water. Less water results in lower capillary forces. If the water has a thickness of just a couple of monolayers ordering phenomena set in, resulting in strong stick slips. As usual in tribology, it is too hard to forecast what friction will be like. Thus, it is always necessary to measure. Best Regards, Matt Dr. Matthias Scherge Microtribology Group Technische Universitaet Ilmenau PF 100565 D-98684 Ilmenau Tel +49 3677 3782 Fax +49 3677 3771 ttp://imath.mathematik.tu-ilmenau.de/phys/personal/tribo.html