Fig. 3: Bidirectional deformation mechanism of windmill structures.
From: Silicon nano-kirigami with controlled plastic, elastic and hysteretic deformations

a SEM images of cantilever (deformed firstly downward and then upward), windmill (reversed from up to down) and Archi-270 spiral structure (reversed from downward to upward, and then back to downward) under FIB irradiation with increased dose. Scale bars: 1 µm. b Deformation height of the windmill in (a) (measured at point C) versus irradiated Ga+ dose. The Ga+ irradiations are with (I) zero dose, (II) low dose of 4.08 × 1015 atoms/cm² and (III) high dose of 6.8 × 1015 atoms/cm². c Schematic diagram of silicon thin film under Ga+ irradiation. d Distributions of the induced vacancies and the probability distribution of Ga+ implantation versus the depth of silicon film. e Calculated distribution of resultant forces within a silicon film and the schematic illustration of moments. (\(\left|{k}_{1}/{k}_{2}\right|\,=\,2.15\)). f Calculated deformation heights and corresponding moments of windmill structures versus \(\left|{k}_{1}/{k}_{2}\right|\). Inset, numerically simulated images of the deformed windmill at each case.