Design concept of the SCS. a) Definition of (i) design parameters and their correspondence to (ii) structural parameters. b) Effect of linewidth L on the SCS formation. As L increased, the amplitude d of the SCS increased, and the half-wavelength w decreased. c) Effect of n on the SCS formation, where n corresponds to the number of half-wavelengths. d) Relationship between the line interval i and d and w, as determined using 60 samples of the SCS. The circle plots represent the amplitude, and the cross plots represent the half-wavelength.