title: Improved optical transmission and current matching of a triple-junction solar cell utilizing sub-wavelength structures.
abstract: Sub-wavelength antireflective structures are fabricated on a silicon nitride passivation layer of a Ga₀.₅In₀.₅P/GaAs/Ge triple-junction solar cell using polystyrene nanosphere lithography followed by anisotropic etching. The fabricated structures enhance optical transmission in the ultraviolet wavelength range, compared to a conventional single-layer antireflective coating (ARC). The transmission improvement contributes to an enhanced photocurrent, which is also verified by the external quantum efficiency characterization of the fabricated solar cells. Under one-sun illumination, the short-circuit current of a cell with sub-wavelength structures is enhanced by 46.1% and 3.4% due to much improved optical transmission and current matching, compared to cells without an ARC and with a conventional SiN(x) ARC, respectively. Further optimizations of the sub-wavelength structures including the periodicity and etching depth are conducted by performing comprehensive calculations based on a rigorous couple-wave analysis method.
authors.affiliation: Department of Photonics, Display Institute, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: M-Y
authors.initials: MY
authors.lastname: Chiu
authors.forename: C-H
authors.initials: CH
authors.lastname: Chang
authors.forename: M-A
authors.initials: MA
authors.lastname: Tsai
authors.forename: F-Y
authors.initials: FY
authors.lastname: Chang
authors.forename: Peichen
authors.initials: P
authors.lastname: Yu