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In this paper we demonstrate the fabrication and application of an electrostatic actuated tensile straining test (EATEST) device enabling strain engineering in individual suspended nanowires (NWs). Contrary to previously reported approaches, this special setup guarantees the application of pure uniaxial tensile strain with no shear component of the stress while e.g. simultaneously measuring the resistance change of the NW. To demonstrate the potential of this approach we investigated the piezoresistivity of about 3 μm long and 100 nm thick SiNWs but in the same way one can think about the application of such a device on other geometries, other materials beyond Si as well as the use of other characterization techniques beyond electrical measurements. Therefore single-crystal SiNWs were monolithically integrated in a comb drive actuated MEMS device based on a silicon-on-insulator (SOI) wafer using the vapor-liquid-solid (VLS) growth technique. Strain values were verified by a precise measurement of the NW elongation with scanning electron microscopy (SEM). Further we employed confocal μ-Raman microscopy for in situ, high spatial resolution measurements of the strain in individual SiNWs during electrical characterization. A giant piezoresistive effect was observed, resulting in a fivefold increase in conductivity for 3% uniaxially strained SiNWs. As the EATEST approach can be easily integrated into an existing Si technology platform this architecture may pave the way toward a new generation of nonconventional devices by leveraging the strain degree of freedom.

In this paper we demonstrate the anisotropic lithiation of silicon (Si). Therefore specimens with radiating Si beams were selectively covered with pure lithium (Li) and lithiation was investigated at different temperatures. Due to the radial arrangement, Si beams underwent a crystallographic orientation dependent lithiation. The experiments showed up to 40% faster lithiation in (110) crystallographic directions compared to (100) oriented Si, and a temperature dependence of the lithiation propagation with lithiation rates of up to 337 nm s(-1) at 100 °C. These results were reflected in prior observation of (110)-orientated Li-Si dendrites, formed after mechanical contact of Li with a Si device layer of a silicon-on-insulator wafer.