Black GaAs with Sub-Wavelength Nanostructures Fabricated via Lithography-Free Metal-Assisted Chemical Etching

Abstract

A highly practical nanofabrication process is detailed here for the generation of black GaAs. Discontinuous thin films of Au nanoparticles are electrodeposited onto GaAs substrates to catalyze site-specific etching in a solution of KMnO4 and HF according to the metal-assisted chemical etching mechanism. This provides a completely solution-based and lithography-free method for fabrication of sub-wavelength nanostructure arrays, which exhibit solar-weighted reflectance approaching 4%. This two-step benchtop process can be entirely performed at room-temperature without lithographic patterning or vacuum instrumentation, providing an alternative high- throughput nanotexturing approach for thin-film photovoltaics applications.