General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect

Abstract

Mechanical anisotropy and point defects would greatly affect the product quality while producing silicon wafers via diamond-wire cutting. For three major orientations concerned in wafer production, their mechanical performances under the nanoscale effects of a point defect were systematically investigated through molecular dynamics methods. The results indicated anisotropic mechanical performance with fracture phenomena in the uniaxial deformation process of monocrystalline silicon. Exponential reduction caused by the point defect has been demonstrated for some properties like yield strength and elastic strain energy release. Dislocation analysis suggested that the slip of dislocations appeared and created hexagonal diamond structures with stacking faults in the [100] orientation. Meanwhile, no dislocation was observed in [110] and [111] orientations. Visualization of atomic stress proved that the extreme stress regions of the simulation models exhibited different geometric and numerical characteristics due to the mechanical anisotropy. Moreover, the regional evolution of stress concentration and crystal fracture were interrelated and mutually promoted. This article contributes to the research towards the mechanical and fracture anisotropy of monocrystalline silicon.

Revisiting the Rate-Dependent Mechanical Response of Typical Silicon Structures via Molecular Dynamics

“…If we compare the fracture patterns of Mono-Si and SiNW, it is clear that the slip fracture tends to occur in SiNW while the cleavage fracture is more likely to appear in Mono-Si. This result shows great consistency with the existing literature [ 42 , 43 ].…”

Misorientation and Temperature Dependence of Small Angle Twist Grain Boundaries in Silicon: Atomistic Simulation of Directional Growth

“…The structural and energetic characteristics of each stage are concluded as given below: in the (11̅ 1) plane). As shown in Figure 6b, the dissociations are on the slip planes and generate stacking faults (see the work of Wan et al 85 , (111) and (11̅ 1)…”

“…In Figure a,b, some b = 1/2⟨110⟩ screw dislocations have dissociated to two b = 1/6⟨112⟩ partial dislocations (e.g., 1 2 [ 110 ] → 1 6 [ 21 1̅ ] + 1 6 [ 121 ] in the (11̅1) plane). As shown in Figure b, the dissociations are on the slip planes and generate stacking faults (see the work of Wan et al for identification of stacking faults) because the dissociated dislocations are the partial type. Only two types of b = 1/2⟨110⟩ screw dislocations and four different dissociation planes exist for a twist GB (e.g., (1̅11) and (111̅) corresponding to b = 1 2 [ 1̅ 1 1̅ ] , (111) and (11̅1) corresponding to b = 1 2 [ 1̅ 11 ] ); therefore, as shown in Figure b,d, the dissociated dislocations are pinned in the dislocation junction and “8” shape structures are observed.…”

On the Formation and Multiplicity of Si [001] Small Angle Symmetric Tilt Grain Boundaries: Atomistic Simulation of Directional Growth

“…Stress Fields. Stress fields near the STGBs are crucial for the mechanical stability of silicon wafers 73 as the extreme stress concentration is induced by dislocations. With the isotropic process of elastic modulus, the stress fields of a screw dislocation in an infinite elastic medium could be computed using the standard methods of elasticity mechanics.…”