Figure 2.

(a–c) Calculated absorptivity of (a) a bare GaAs substrate and that of a GaAs substrate with close-packed monolayer 700 nm SiO₂ nanosphere arrays for (b) TE and (c) TM incident polarization. Calculations are based on FDTD methods and made as a function of both incident angles (θ = 0° to 55°) and wavelengths (λ = 400 nm to 860 nm). (d–e) Measured absorptivity of (d) a bare GaAs solar cell and (e) that of a GaAs solar cell with SiO₂ nanospheres atop. Measured absorptivity is determined as a function of both incident angles (θ = 10° to 55°) and wavelengths (λ = 400 nm to 860 nm), and measurements are made using an integrating sphere with monochromatic light from a xenon arc lamp. (f) Normalized electric field intensity profiles (|E|²) within nanospheres at selected wavelengths for both incident polarizations at normal incidence. Scale bars are 250 nm.