Research On Adsorption-Desorption Problem In Nems

In the field of Microelectromechanical Systems(MEMS), with the request of improving device parameters, the device dimensions are scaling down to submicrons and even nanometers, which causes the appearance of a new concept based on MEMS technology-Nanoelectromechanical Systems(NEMS). But NEMS is not MEMS only by scaling down the device dimension, and the methodology of NEMS is also different from MEMS, since the NEMS devices have shown some quantum effects in the scale of nanometers and we can't use classic physics to describe their behaviors.With the scaling down of the devices dimensions, the surface-to-volume ratio s/v is becoming larger, and all sorts of surface effects become more and more obvious, of which the adsorption-desorption problem is the main aspect.There are two cases according to the kinetics equilibrium in adsorption theory: single-layer adsorption and multi-layer adsorption. We analyzed the adsorption-desorption influence on resonant frequency, quality factors of the NEMS devices in the case of multi-layer adsorption. And we have also made some calculations and obtained the numerical results. At last we give a brief introduction about the latest research on adsorption-desorption noise.The numerical results show that both the single-layer adsorption theory and multi-layer adsorption theory have a saturated value of the adatoms. The only difference is that the inflexion is not the same, which is caused by the difference between the two adsorption theories. Single-layer adsorption theory can be applied in low pressure and multi-layer adsorption theory should be used in higher pressure.