Effect of Side Surface Orientation on the Mechanical Properties of Silicon Nanowires: A Molecular Dynamics Study

Xiao Zhuo,Hyeon Beom

doi:10.3390/cryst9020102

Abstract

We investigated the mechanical properties of <100>-oriented square cross-sectional silicon nanowires under tension and compression, with a focus on the effect of side surface orientation. Two types of silicon nanowires (i.e., nanowires with four {100} side surfaces and those with four {110} side surfaces) were simulated by molecular dynamics simulations at a temperature of 300 K. The deformation mechanism exhibited no dependence on the side surface orientation, while the tensile strength and compressive strength did. Brittle cleavage was observed under tension, whereas dislocation nucleation was witnessed under compression. Silicon nanowires with {100} side surfaces had a lower tensile strength but higher compressive strength. The effect of side surface orientation became stronger as the nanowire width decreased. The obtained results may provide some insight into the design of silicon-based nano-devices.

Highlights

Silicon nanowires have attracted tremendous interest from worldwide scientific communities and various industries, because of their extraordinary optical [1], electrical [2], thermoelectric [3], piezoelectric [4], and mechanical [5] properties
As an essential building block in nanotechnology, silicon nanowires have been widely applied in nanoelectromechanical systems, such as field effect transistors, nanoresonators, nanosensors, light-emitting diodes, logic gates, and battery anodes
We aim to investigate themolecular influencedynamics of side surface properties of silicon nanowires

Summary

Introduction

Silicon nanowires have attracted tremendous interest from worldwide scientific communities and various industries, because of their extraordinary optical [1], electrical [2], thermoelectric [3], piezoelectric [4], and mechanical [5] properties. As an essential building block in nanotechnology, silicon nanowires have been widely applied in nanoelectromechanical systems, such as field effect transistors, nanoresonators, nanosensors, light-emitting diodes, logic gates, and battery anodes. In these devices, silicon nanowires are often under extreme loading conditions. Because of the Li insertion [6]; in the silicon-based field effect transistors, silicon nanowires can be strained more than 12% [7]. To maintain the reliability of these devices, it is essential to gain a thorough knowledge of the mechanical properties of silicon nanowires Once the applied strain exceeds a critical value, dislocations or cracks may initiate in silicon nanowires, which can degrade the function of these silicon-based devices.

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