AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Wednesday Sessions
       Session MM+NS-WeM

Paper MM+NS-WeM8
Controlling Energy Losses in Nanoscale Structures with Surface Chemistry

Wednesday, November 6, 2002, 10:40 am, Room C-210

Session: Nanotechnology and Nanofabrication in NEMS
Presenter: J.A. Henry, Cornell University
Authors: J.A. Henry, Cornell University
Y. Wang, Cornell University
M.A. Hines, Cornell University
Correspondent: Click to Email
Why are we unable to predict the dynamic properties of nanoscale devices from the well -known behavior of bulk materials? For example, the quality (or Q) of nanoscale resonators is often orders of magnitude lower than similar macroscopic devices. Here, we show that simple changes in the surface chemistry of MHz silicon resonators can lead to large changes in Q, indicating that surface loss mechanisms become very important at this length scale. For example, the oxidation of H-terminated silicon resonators causes the Q to plummet by as much as 50% while inducing only a minuscule change in frequency of approximately 0.05%. The scaling of both the energy losses and the frequency shifts with oscillator size and thickness are consistent with a surface-driven process. Infrared absorption measurements confirm that chemical changes are limited to a few monolayers of the surface. Possible mechanisms for these losses will be discussed.