Hydrofluoric-treated GaAs surfaces analyzed by contact angle measurement and Auger electron spectroscopy

A GaAs surface chemically treated with hydrofluoric (HF) acid was characterized using measurement of the contact angle between,the GaAs surface and a water droplet on it and through Auger electron spectroscopy (AES). The surface oxide layer formed on Gal-is during planar etching was removed by dipping it into HF solution. As the dipping time increased, a thicker arsenic layer was formed on the GaAs surface, which prevented the surface oxidation of the substrate. This is reflected in an increase in the contact angle. When the dipping time becomes very long (180 min), the amount of surface oxygen increases probably due to the roughened surface of the GaAs substrate, resulting in a decrease in the contact angle.