Surface texturing of GaAs using a nanosphere lithography technique for solar cell applications

In this study, we present novel methods to texture the surface of GaAs substrates using the nanosphere lithography (NSL) technique that is based on arrays of SiO₂ nanospheres. Closed-packed arrays of SiO₂ nanospheres were formed on a benzocyclobutene (BCB) layer, followed by embedding SiO₂ nanospheres into the BCB layer. To texture the GaAs surface, three patterns were fabricated by nanosphere lithography. First, a convex pattern from the shape of the nanospheres was produced on the surface of GaAs. Second, a concave shape was produced on the surface of GaAs by additional wet etching to remove SiO₂ nanospheres. These two methods were found to be effective in reducing the reflectance to a range of 400-800 nm. Finally, the arrays of SiO₂ nanospheres were transferred onto the GaAs by dry-etching using a mixture of Cl₂ and BCl₃ gases, resulting in arrays of GaAs nanorods. The dry-etched surface structure showed the lowest reflectance.