Improved absorption efficiency of silicon (Si) solar cells through Resonant Waveguide Gratings (RWGs) - A hybrid design of RWG and Si solar cell

This research work focuses on the improved performance of a Si solar cell by increasing solar absorption. The silicon solar cell is designed with a hybrid photonic structure of Resonant Waveguide Gratings (RWGs) to enhance absorption efficiency. The Waveguide Gratings have been designed in Fourier Model Method (FMM) using regression algorithm. The subsequent hybrid design of RWG with Si solar cell has been carried out using Finite Difference Time Domain (FDTD) design tool. The grating corrugated layer is designed in a fused silica (SiO2) material and coated with a high index amorphous TiO2 material. One of the possible realizable grating designed parameters are: grating period d = 316 nm, refractive index of TiO2, nt = 2.385, refractive index of fused silica ns = 1.450, duty cycle = 65%, structure line width w = 205 nm, resonance wavelength λr = 632.8 nm (Helium-Neon laser), angle of incidence θi = 18°, and grating grooved height hg = 120 nm, whereas the designed parameters for Si solar cell are: refractive index of Si N = 3.882 + i(0.019) at resonance wavelength λr = 632.8 nm, cell thickness T = 500nm. The employment of optimized grating parameters in simulations leads to efficient hybrid device performance.