Theoretical Study On The Mechanical And Thermal Properties Of Oxidized Single Crystal Silicon Nanostructure

Silicon is the most abundant element on the earth,and single crystal silicon is the main raw material of semi-continuous electronic devices.With the progress of nanotechnology,the characteristics of silicon nanostructures have also become a critical topic in the basic research of semiconductor nanostructures.Oxidation of structure is an unavoidable problem in silicon processing.When the size of silicon structure decreases into nano-scale,the influence of oxide layer on its performance will be increasingly indispensable.In this paper,we utilized the theoretical calculation to accomplish the mechanical properties and the influence of temperature on mechanical properties of silicon nanostructures with oxide layers on the surface.There are three parts in this paper.(1)Established the semi-continuous model of silicon nano-film,Young's modulus of phosphor doped silicon nano-film with oxide layer was researched by utilized Keating deformation potential.The results suggested that Young's modulus of silicon nano-film with oxide layer is inversely proportional to its thickness,that is to say,Young's modulus will increase with the reduction of thickness,and finally tend to constant value.Young's modulus of silicon nano-film with oxide layer on surface is higher compared to silicon film without oxide layer.This calculation show that the oxide layer exhibit improved Young's modulus of silicon nano-film.Besides,the larger of thickness of oxide layer,the larger of Young's modulus of silicon nano-film.(2)Young's modulus of silicon nano-film with oxide layer on surface is calculated by using anharmonic Keating deformation potential at local temperature.At the same time,the effect of oxide layer number on Young's modulus is also considered.The results suggested that the Young's modulus is inversely proportional to the temperature.In other word,the Young's modulus reduces with the rises of temperature.Besides,Young's modulus of silicon nano-film is dependence on the thickness of oxide layer.Meanwhile,when silicon nano-film is the same or the number of crystal cell layers is the same in the thickness direction,the young's modulus of silicon nano-film with oxide layer on the surface is larger than that of silicon nano-film without oxide layer,The existence of oxide layer leads to the improved of Young's modulus of silicon nano-film.(3)The resonance frequency of silicon nano-beam with oxide layer on surface is studied,and the dependence of resonance frequency on size is discussed.The results regard that the vibration behavior of silicon nano-beam without oxide layer on the surface is quite different from of silicon nano-beam with oxide layer,which of the former is higher than the latter.In addition,the size of the silicon nano-beam has a great influence on the vibration behavior,the resonance frequency increases monotonically with the increase of the size.At the same time,temperature has an influence on vibration behavior slightly.The simulation results by molecular dynamics(MD)are also show in this chapter as comparisons.