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

A practical nanofabrication process is detailed for the generation of black GaAs. Discontinuous films of Au nanoparticles are electrodeposited onto GaAs substrates to catalyze site-specific etching in a solution consisting of KMnO4 and HF via the metal-assisted chemical etching. This provides a solution-based and lithography-free method for fabricating sub-wavelength nanostructure arrays that exhibit solar-weighted reflectance approaching 4%. This two-step benchtop process can be performed at room-temperature without lithography, vacuum instrumentation, or epitaxy, providing a high-throughput nanotexturing approach for photovoltaics applications. (c) 2019 The Electrochemical Society.