Fig. 1

Materials characterization, fabrication and optical properties of nanomeshed Si nanomembranes. a A scanning electron microscope (SEM) image of a Si-nanomesh film. The left inset is a photograph of the Si-nanomesh film on a twisted PDMS substrate. The right inset is an atomic force microscope (AFM) image of an area in the Si nanomeshes. The scale bar in a, left inset and right inset are 10 μm, 5 mm and 5 μm, respectively. b Schematic illustration of the stretchable PI/Si bilayer nanomeshes on the PDMS substrate. Raman spectra (c) and X-ray diffraction pattern (d) of Si nanomeshes (red) and a single-crystalline Si wafer (black), showing the single-crystalline nature of Si traces. e Schematic illustration of the transfer process to achieve stretchable PI/Si bilayer nanomeshes. This process starts by forming the Si layer in an SOI wafer into nanomeshes from a modified In grain boundary lithography and dry etching. An ultrathin PI film secures the nanomeshes during the wet etching of the buried oxide (BOX) layer. After being picked up by PDMS, patterning the PI film using Si nanomeshes as a self-aligned mask completes the formation of PI/Si nanomeshes. f SEM images of the Si nanomeshes with different fill factors controlled by the HNO₃ etching in the In grain boundary widening. The scale bar is 1 μm. g Transmittance spectra of Si nanomeshes with different fill factors in the wavelength range of 300–1100 nm