Fig. 3
Computational and experimental investigation of the dependence of crack suppression on the acceleration voltage (VA). a Distribution of the energy of the irradiated electrons absorbed in the Cu film–PI system at different values of VA ranging from 3 kV to 25 kV. The absorbed energy in the Cu film (0 nm ≤ z ≤ 100 nm) and the PI substrate (100 nm ≤ z ≤ 250 nm), in unit of keV m−3·electron, was calculated using the CASINO Monte Carlo software. b Transmission coefficients (defined as the ratio of the number of electrons transmitted through the Cu thin film to that of the total incident electrons) as a function of VA obtained from the Monte Carlo calculation (left, blue). Also shown in b is the relative crack densities at a tensile strain of 30% (right, red) experimentally determined from the SEM images shown in c. Error bars represent the standard deviations. Scale bar, 5 μm
