Fig. 2: Key characteristics of the ablation process.

Controlled reductions in thicknesses of monocrystalline Si MMs achieved by ablation, and their dependence on ablation parameters, including average power (a), scanning speed (b), frequency (b), and the number of repetitions (c) at fixed grid distance (7 µm) and grid mode (XY-parallel). The shaded areas denote the standard deviation. Schematic illustration of cross-sectional profiles of ribbon-shaped structures of monocrystalline Si MM formed by ablation; a trapezoid shape with a titled edge (projected width larger than the laser spot diameter D_laser; case 1; d), a triangle shape at the critical point (projected width similar to D_laser; case 2; e), and a proportionally reduced triangle shape (projected width smaller than D_laser; case 3; f). g Experimentally measured profiles for these three cases. Peak height (h) and effective width (i) as functions of projected width. The effective width corresponds to the integrated cross-sectional area divided by the peak height. The minimum feature size is ~5 µm. The shaded areas denote the standard deviation. j Alignment accuracy in the x- and y-axis is 2.7 ± 1.3 and 3.1 ± 1.2 µm, respectively. k Minimized damage to underlying materials following laser ablation processing of the top layer. Ablating a 500-nm-thick top Si MM layer leads to an ablated thickness of ~80 nm for the underlying PLA layer (original thickness: 50 µm); ablating a 300-nm-thick top Mg layer leads to an ablated thickness of ~50 nm for the underlying Si layer (original thickness: 500 nm). l, Root-mean-square (RMS) line edge roughness for Si (thickness: 2 µm; width: 100 µm) and Mg (thickness: 500 nm; width: 100 µm) ribbons patterned on PLA substrates (thickness: 50 µm) are 1.1 ± 0.4 µm and 0.8 ± 0.2 µm, respectively. Insets: SEM images (titled angle: 45°) of a bi-layer Mg/Si structure (thickness: 300 nm for top Mg and 2 µm for bottom Si) on a PLA substrate (thickness: 50 µm).