Nano/micro dual-textured antireflective subwavelength structures in anisotropically etched GaAs

Light trapping by surface texturing is widely used to improve the performance of optoelectronic devices. In this Letter, we demonstrate nano/micro dual-scale textured GaAs by integrating triangular GaAs by orientation-dependent wet etching and subwavelength nanoholes by metal-assisted chemical etching (MacEtch). This is the first report on nano/micro dual-scale textured GaAs. The reflectance was adjusted by controlling the aspect ratio of the nanoholes by varying the MacEtch duration. The combination of the microstructure and subwavelength structures significantly reduced the solar-weighted reflectance of a bare GaAs substrate by 72%.