Stability Of Micro-nanodevices In The Presence Of Quantum Effect

The Casimir effect is a quantum effect.It results from the alteration by the boundaries of the zero-point electromagnetic energy,and it is a direct manifestation of the boundary dependence of quantum vacuum.It is observed as an attractive force between two parallel conducting plates.The Casimir force is too small to be observed between plates that are several meters apart,but in sub-micro meter range, it could be the biggest force between two objects.Two plates separated by a distance of 10 nm have an attractive Casimir pressure of about an atmospheric pressure.One fundamental problem in NEMS operation with typical sizes in the micro-meter range or below is the stiction/adhesion phenomenon,the permanent adhesion of moving parts when they are brought in close proximity to each other.In sub-micro meter range,The Casimir force is one of the most important origins of this phenomenon.In this thesis,the zero-point energy related to Casimir effect was studied,and the derivation of the Casimir force between to parallel perfect conducting plates in vacuum was given.Some important experiment about the Casimir effect were introduced and the applications of the Casimir effect were also discussed.A one-degree of freedom simple-lumped model is adopted and the stability behavior of the system influenced by the Casimir force is obtained.There is a critical initial gap between two plates in a simple-lumped system.When the initial separation is less than the critical value(pull-in gap),the two plats will jump into contact with each other.When the voltage applied across the plates reaches a critical value(pull-in voltage),The plates will jump into contact,too.The influence of the dielectric properties of the materials,as well as of the roughness of the surface and of the environment temperature,was full taken into consider.The effect of the conductivity and surface roughness increased significantly with the decrease of the distance between two plates,which could cause great influence on the stability behavior of MEMS/NEMS.Compared with the other two effects,the environment temperature just plays a marginal role in sub-micro meter range.Two important pull-in parameters,the pull-in gap and the pull-in voltage,of nano switches were calculated.The correction factors of the conductivity,surface roughness and the temperature were brought into the calculation and the influence of the material properties and the environment temperature was intensively discussed.The acoustic Casimir effect was also introduced.Besides zero-point field(ZPF) Casimir force,the acoustic Casimir force also play a significant role in the stability behavior of nano-switches.The infuence of the temperature also become very important because of the acoustic Casimir force.In the production of MEMS/NEMS,by using the proper materials and controlling the environment temperature,the stability of the system could be improved significantly.