Fig. 1. The flows of two different preparation methods for freestanding films. (a) Conventional floating method; (b) improved method

Fig. 2. The construction of finite element model. (a) 2D geometric model; (b) initial state; (c) finite element meshing

Fig. 3. Relationship between transfer angle and equivalent stress on films. (a) Temporal evolution of maximum stress under various transfer angles; (b) comparison of peak stress at different angles

Fig. 4. Relationship between film equivalent stress and flow rate at 90° transfer angle, as a function of transfer time or flow rate. (a) Evolution of maximum stress on the film over time at different fluid flow rates; (b) relationship between peak stress and fluid flow rate

Fig. 5. Distribution of stress on film surface at 0°transfer angle for Zr,Si,and SiC materials

Fig. 6. At different transfer angles, the level of the liquid phase relative to Si thin-film and external support frame when the stress reaches its peak level (left) and distribution of stress on film surface at this moment (right).(a) 30° transfer angle, the level of the liquid phase at 337 s; (b) 45° transfer angle, the level of the liquid phase at 323 s; (c) 60° transfer angle, the level of the liquid phase at 320 s; (d) 90° transfer angle, the level of the liquid phase at 382 s

Fig. 7. Photos of freestanding film samples. (a) Zr film: intact sample prepared by the transfer angle of 90° (top), and the broken sample prepared by the conventional floating method (bottom); (b) Si film: intact sample prepared by the transfer angle of 90° (top), and the broken sample prepared by the conventional floating method (bottom); (c) freestanding 50 nm-thin Si film sample: successfully prepared by our optimized process design (90°, 0.1 mm/s)