Figure 3

Room temperature absorption coefficient of annealed SiO _x /SiO ₂ multilayer films with various x (1,100°C, 1 h; [11]). There is a strongly absorbing region at energies above 3 eV, in which absorption increases with the Si content of the layers, and a weakly absorbing region at less than 3 eV, which is not strongly affected by Si content.