Permanent, macroscopic deformation of single crystal silicon by mild loading

Silicon is usually considered a brittle material. However, under specific conditions, such as high temperature, high confining pressure, and complex loading patterns involved in surface machining or microindentation, extremely localized regions with plastic deformation may show up. Herein this paper, we demonstrate the possibility to induce a permanent deformation field extending over macroscopically wide regions, with no need for extreme load. Indeed, this is obtained at room temperature upon applying a relatively small pressure onto single crystal silicon slices machined with a pre-notch at the bottom surface. To deeply characterize the deformed region, which is visible to the naked eye, we adopted an experimental multiscale approach, which involves a combination of optical microscopy and profilometry, Raman spectroscopy, and Electron Backscatter Diffraction (EBSD). Overall, the results collected via different techniques show, in a consistent fashion, that our proposed methodology is an effective engineering pathway to induce controlled permanent deformation in silicon samples, whose effects can be observed across different length scales, from macro to nano.