Effects of Surface Chemical Structure on the Mechanical Properties of Si_1–xGe_x Nanowires

Abstract

The Young's modulus and fracture strength of Si(1-x)Ge(x) nanowires (NWs) as a function of Ge concentration were measured from tensile stress measurements. The Young's modulus of the NWs decreased linearly with increasing Ge content. No evidence was found for a linear relationship between the fracture strength of the NWs and Ge content, which is closely related to the quantity of interstitial Ge atoms contained in the wire. However, by removing some of the interstitial Ge atoms through rapid thermal annealing, a linear relationship could be produced. The discrepancy in the reported strength of Si and Ge NWs between calculated and experimented results could be related to SiO(2-x)/Si interfacial defects that are found in Si(1-x)Ge(x) NWs. It was also possible to significantly decrease the number of interfacial defects in the NWs by incorporating a surface passivated Al2O3 layer, which resulted in a substantial increase in fracture strength.

Vibrational and mechanical properties of Si/Ge nanowires as resonators: A molecular dynamics study

“…However, unresolved issues still remain in the potential use of Si/Ge nanocomposites as resonators. To our knowledge, though there have been many reports for the investigation of SiGe NWs as potential thermolectric or electronic devices , a theoretical study for their potential use as resonators has not been reported yet. On the other hand poly‐SiGe has been recently used for building MEMS resonators and very efficient biosensors .…”

Compositional and structural engineering of inorganic nanowires toward advanced properties and applications

“…20 The Young's modulus of Si 1-x Ge x [111] NWs was investigated through tensile stress measurements as a function of the Ge concentration with a mechanical testing system integrated on an SEM platform ( Figure 9B). 134 As shown in Figure 9C, left, the Young's modulus gradually decreases with increasing Ge content, which indicates an approximately linear relation with the relative compositions of Si and Ge. Notably, the nanowires display no obvious law of fracture stress and strain due to the existence of Ge i and surface defects.…”

“…In composition‐tunable alloy compounds, such as Si 1‐ x Ge x , the Young's modulus is presented as Y 110 = (169–31 x ) GPa along the [110] direction . The Young's modulus of Si 1‐ x Ge x [111] NWs was investigated through tensile stress measurements as a function of the Ge concentration with a mechanical testing system integrated on an SEM platform (Figure B) . As shown in Figure C, left, the Young's modulus gradually decreases with increasing Ge content, which indicates an approximately linear relation with the relative compositions of Si and Ge.…”

“…C, Young's modulus, fracture strength, and fracture strain of Si 1 − x Ge x NWs without/with an Al 2 O 3 shell. Reproduced with permission . Copyright 2013, American Chemical Society.…”

“…Reproduced with permission. 134 Copyright 2013, American Chemical Society. D, Setups designed for in situ TEM bending of core-shell Ge-Si nanowires during electrical or mechanical measurements, E, HRTEM image of a core-shell NW.…”