“Deep Ultra-Strength”-Induced Band Structure Evolution in Silicon Nanowires

Abstract

Recently we experimentally demonstrated that vapor−liquid−solid (VLS) grown silicon (Si) nanowires can be stretched to above 10% elastic strain through in situ nanomechanical strategies (Zhang et al. Sci. Adv. 2016, 2 (8), e1501382). Here, based on first-principles calculation, the geometric and electric properties of <110>-oriented Si nanowires with diameter ∼1.5 nm under ultralarge strain are comparatively investigated. The anisotropic Poisson effect was observed in the silicon nanowire that the change of diameter along the (100) orientation decreases dramatically while that along the (110) orientation shows only minor influence. For the purpose of obtaining a thorough understanding of the influence of applied strain on the electronic properties, the electronic band structure, effective mass of electron, and work function are systematically studied. Direct-to-indirect band gap transformation occurs for hydrogen terminated nanowires when the applied strain is larger than 4%. When the applied strain is more than 19% (may vary depending on different chemical modifications), the Si nanowires could even transform from semiconductor to metallic behavior, with no band gap! Our results show the possibility of tuning Si nanowires' electronic properties through mechanical straining, which may offer a new route in Si-based optoelectronics applications.

Elastic properties and tensile strength of 2D Ti3C2Tx MXene monolayers

“…It is worth noting that if there are a large number of defects in the 2D materials’ internal region, which will obviously modulate the fracture behavior and result in multiple crack stages 55 . Furthermore, the fracture strength of the sample with edge defects remains in the same order of magnitude as the ideal strength of the defect-free sample, and the experimental measurements exceed half of the ideal value (i.e., deep ultra-strength 56 ). These effectively demonstrate that the effect of FIB on the fracture strength of monolayer Ti 3 C 2 T x nanosheets is confined to the edge area only.…”

Strained diamond for quantum sensing applications

“…For example, it has been demonstrated that high-quality silicon nanowires can be stretched elastically above 10%, which is more than half of its theoretical limit (17%-20%) [92]. Accordingly, first principles calculations predicted an indirect to direct bandgap transition and a metallization transformation with ultra large strain of Si [93,94], indicating the great potential of DESE, and one may think about what DESE can do for further tuning the optical, electronic and even quantum mechanical properties of more materials.…”