The Tensile Simulation Of Silicon Nano-wire Based On Molecular Dynamics

Silicon nano-wire has excellent semiconductor stability, electronic transmissionand lower field emission opening voltage, so the application potential in nano-devicesis very great. As the experiment study on the nano-wire is limited by the experimentalequipments, the computer numerical simulation becomes an important method tostudy the physical and mechanical properties of the nano-wire.Molecular dynamics (MD) is often used in computer numerical simulation of thenano-wire, i.e. atomic systems are simulated in the use of the classical mechanicsprinciple. Firstly, the mechanical properties of a silicon nano-wire are studied by MDin this paper, and the stress-strain curve of the silicon nano-wire is obtained. It can beseen from the stress-strain curve that the silicon nano-wire has no significant plasticflow, but the necking phenomenon happens during the tension process. Themechanical properties of perfect and defective nano-wires are studied, it is found thatthe strength would be greatly decreased when the defects exist, and the fractureemerges at the defective location. The mechanical properties of silicon nano-wireswith different cross-sections are studied, and the results obtained show that themaximum stress and strain of silicon nano-wires increase when the size of thecross-section becomes larger. In addition, the influences of the temperature and strainrate are studied, and the study shows that the maximum stress and strain greatlyreduce as the temperature increases. When the temperature increases to1000K, thesilicon nano-wires display a melted state, and lose the capability subjected loads. Incontrast, the maximum stress and strain increases, when the strain rate increases.Finally, the effects of the length and size of the defective cross-section on themechanical properties are investigated. When the length of the defects graduallybecames larger, the maximum stress and strain would firstly become smaller, thenslowly increase. Moreover when cross-sectional size of the defects becomes larger,the toughness of the nano-wire would be better.The effects of the defects, the size of the cross-section and length of the siliconnano-wire, temperature and strain rate on tensile properties for the silicon nano-wireare respectively studied by MD method in this paper. Some significant results areobtained, which would provide valuable reference for the application of the siliconnano-wires in nano-devices.