Optical design of GaN/In(x)Ga(1-x)N/cSi tandem solar cells with triangular diffraction grating

Optical design in enhancing optical absorption of group-III-nitride- and multiple quantum well-based GaN/InxGa_1-xN/cSi dual-junction tandem solar cells with triangular diffraction grating is simulated and optimized by using combined two-dimensional rigorous coupled wave analysis and transfer matrix methods. This paper thoroughly examines these phenomena of optical absorption affected by antireflection coatings, multiple thin-film layers and diffraction gratings with the integrated perspectives of semiconductor physics and electromagnetic theory for the first time. An improvement of 58% in absorption compared to the prototype SC is obtained which means more than 80% of incoming light (hυ > Eg_Si) can be harvested in this thin-film (< 4 μm in total) design.