Effect of surface residual stress and surface layer stiffness on mechanical properties of nanowires

Zhang, Y.; Cai, Jun; Mi, Changwen; Wang, Fangxin; Akbarzadeh, A.H.

doi:10.1007/s00707-021-03112-3

Cited by 7 publications

(5 citation statements)

References 87 publications

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“…40 Similarly, classical beam theories are extended through considering the surface flexural stiffness 41−43 along with the different surface elasticity models. 32,33,44 However, the results e m p l o y e d t o m o d e l t h e b e n d i n g r esponse 21,23,27,29,32,33,45 have so far delivered various degrees of success for the estimation of size-dependent NW properties. (iii) Other structural aspects such as finite deformation, intrinsic stresses, and appropriate boundary conditions have to be modeled for mechanical consistency and relevance with respect to experimental conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Despite progress, anistropic treatment of Si NW surface properties remains as the leading challenge in this field. 20,33,45 The present work addresses this challenge through a multiscale nanomechanical model. The proposed model is based on extended YL within the Euler−Bernoulli (EB) beam formulation.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Appropriate interatomic potentials for atomistic simulations of surface stress and surface elasticity have to be introduced. ,, In this regard, surface stress is defined as the reversible work per unit area needed to elastically stretch a pre-existing surface. , Surface elastic constants represent the variation in bulk elastic constants due to the formation of a surface. , The classical surface elasticity theory by Gurtin and Murdoch has been widely employed for NWs . Similarly, classical beam theories are extended through considering the surface flexural stiffness − along with the different surface elasticity models. ,, However, the results employed to model the bending response ,,,,,, have so far delivered various degrees of success for the estimation of size-dependent NW properties.…”

Section: Introductionmentioning

confidence: 99%

“…Atomistic simulations also exhibit a reduction in the modulus of elasticity of Si NWs to be as much as 40% due to native oxide surface condition while compared to the pristine surface state. ,, Similar reduction in the ultimate strength is estimated to be up to 20%. ,, Appropriate interatomic potentials for atomistic simulations of surface stress and surface elasticity have to be introduced. ,, In this regard, surface stress is defined as the reversible work per unit area needed to elastically stretch a pre-existing surface. , Surface elastic constants represent the variation in bulk elastic constants due to the formation of a surface. , The classical surface elasticity theory by Gurtin and Murdoch has been widely employed for NWs . Similarly, classical beam theories are extended through considering the surface flexural stiffness − along with the different surface elasticity models. ,, However, the results employed to model the bending response ,,,,,, have so far delivered various degrees of success for the estimation of size-dependent NW properties. Other structural aspects such as finite deformation, intrinsic stresses, and appropriate boundary conditions have to be modeled for mechanical consistency and relevance with respect to experimental conditions. ,,,,,, For example, the residual stress effect is embedded in nanomechanical bending models using different formulations, ,− , the quantification of which is a subject of high technological demand. , Uncertainties associated with boundary conditions can also lead to discrepancies due to their direct impact on the load–displacement relationship …”

Section: Introductionmentioning

confidence: 99%

“…These effects are significant upon large deformation of NWs leading to axial reorientations and phase transformations. , Consequently, the effectiveness of available nanomechanical models ,,− in predicting NW bending behavior is directly related to the extent of their parameter sets. Despite progress, anistropic treatment of Si NW surface properties remains as the leading challenge in this field. ,, …”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Nanomechanical Modeling of the Bending Response of Silicon Nanowires

Zare Pakzad,

Nasr Esfahani,

Tasdemir

et al. 2023

ACS Appl. Nano Mater.

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Understanding the mechanical behavior of silicon nanowires is essential for the implementation of advanced nanoscale devices. Although bending tests are predominantly used for this purpose, their findings should be properly interpreted through modeling. Various modeling approaches tend to ignore parts of the effective parameter set involved in the rather complex bending response. This oversimplification is the main reason behind the spread of the modulus of elasticity and strength data in the literature. Addressing this challenge, a surface-based nanomechanical model is introduced in this study. The proposed model considers two important factors that have so far remained neglected despite their significance: (i) intrinsic stresses composed of the initial residual stress and surface-induced residual stress and (ii) anisotropic implementation of surface stress and elasticity. The modeling study is consolidated with molecular dynamics-based study of the native oxide surface through reactive force fields and a series of nanoscale characterization work through in situ three-point bending test and Raman spectroscopy. The treatment of the test data through a series of models with increasing complexity demonstrates a spread of 85 GPa for the modulus of elasticity and points to the origins of ambiguity regarding silicon nanowire properties, which are some of the most commonly employed nanoscale building blocks. A similar conclusion is reached for strength with variations of up to 3 GPa estimated by the aforementioned nanomechanical models. Precise consideration of the nanowire surface state is thus critical to comprehending the mechanical behavior of silicon nanowires accurately. Overall, this study highlights the need for a multiscale theoretical framework to fully understand the size-dependent mechanical behavior of silicon nanowires, with fortifying effects on the design and reliability assessment of future nanoelectromechanical systems.

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